ArtifactReduction3D MSK MRI withsyngo SPACEPage 6OncologyBone and soft tissuetumor imagingPage 50Whole-body DWIof Bone Mar...
ImprintMAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 107Yes,Iconsenttotheaboveinformationbeingusedforfuturecont...
EditorialMilind Dhamankar, M.D.Sr. Director, MR ProductMarketing, Malvern, PA, USAEditorial BoardWe appreciate your commen...
EditorialMilind Dhamankar, M.D.Sr. Director, MR ProductMarketing, Malvern, PA, USAEditorial BoardWe appreciate your commen...
Clinical 3D Imagingand ArtifactReduction6 3D Musculoskeletal MRI withsyngo SPACEMike Notohamiprodjo12 Imaging of Metallic ...
ContentClinical Oncology50 Bone and Soft Tissue TumorImagingMarcus Pianta, et al.58 How I do itMSK Imaging Tips & TricksMa...
6 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical 3D ImagingBackgroundDue to the excellent soft-tissue co...
MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 73D Imaging Clinicalalso often comprised by partial volumeeffects...
related constraints or missing 3D recon-struction abilities of the PACS system,several previous studies featured time-cons...
syngo SPACE appears particularly prom-ising. Indeed syngo SPACE was superiorto 2D sequences for the depiction of thespheri...
10 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical 3D Imaging4 Combined T1w and T2w syngo SPACE dataset o...
References1 Resnick, D., H.S. Kang, and M.L. Pretterklieber,Internal derangements of joints. 2nd ed2006,Philadelphia: Saun...
12 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Artifact ReductionImaging of Metallic Prostheses Using...
MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 13Artifact Reduction ClinicalThese developments have created anad...
14 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Artifact Reduction2 STIR contrast images of a total kn...
cause more disturbance of the magneticfield than the linear portions [16–20].It is, thus, possible to eliminate a certaina...
reported on MRI of 14 total hip arthro-plasties and found depiction of the peri-prosthetic structures to be of diagnosticq...
using STIR contrast was with SEMAC ata time cost. An example of the conven-tional and SEMAC sequences using STIRcontrast i...
References1 Afolaranmi GA, Tettey J, Meek RM, Grant MH.Release of chromium from orthopaedicarthroplasties. The open orthop...
MAGNETOM Flash · 1/2012 · www.siemens.com/magnetom-world 19Complete spine examinations with ease and fewer errorsProduct N...
20 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Artifact ReductionExperience with the 3 Tesla MAGNETOM...
MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 21Artifact Reduction Clinicaloptimized Contrasts using different ...
22 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldities. Higher magnetic field strengthsproduce larger susceptibi...
MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 23Artifact Reduction Clinical5 Metal implant imaging using syngo ...
24 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldProduct NewsThe term WARP summarizes methods tominimize the imp...
MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 25Product Newsaddresses in-plane distortions: Intra-voxel signal ...
26 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Cartilage ImagingIntroductionArticular cartilage lesio...
MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 27Cartilage Imaging Clinical1 An 18-year-old was involved ina mot...
Clinical Cartilage Imaging2 Post ACI follow up MRI shows satisfactory fill of thelesion. The articular surface of the graf...
lage repair, as it allows prospectivemulticenter studies in which results ofcartilage repair surgeries are compared[1]. An...
30 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Sports and Trauma ImagingPatient historyPatient is a p...
MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 31Sports and Trauma Imaging ClinicalMRI initial study:(Figs. 1A, ...
Surgical findings after second MRI:1. Approximately 1 × 1 cm medialfemoral condyle chondral defect anddelamination posteri...
Table 1: MRI technique.Weighting and planes Field-of-viewTR TE Sequence SlicethicknessGAP Matrix sizeT2-weighted axial 115...
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Magnetom Flash 50 - Revista MRI

  1. 1. ArtifactReduction3D MSK MRI withsyngo SPACEPage 6OncologyBone and soft tissuetumor imagingPage 50Whole-body DWIof Bone MarrowPage 60How I do itMSK imagingTips and TricksPage 58Technology7T MRI for MSKApplicationsPage 98MAGNETOMFlashIssueNumber2/201250SUBSCRIBE NOW!– and get your free copy of futureMAGNETOM Flash! Interesting information fromthe world of magnetic resonance – gratis to yourdesk. Send us this postcard, or subscribe online atwww.siemens.com/MAGNETOM-WorldMAGNETOMFlashSiemensAGMedicalSolutionsMagneticResonanceAntjeHellwich-MarketingP.O.Box3260D-91050ErlangenGermanyOn account of certain regional limitations ofsales rights and service availability, we cannotguarantee that all products included in thisbrochure are available through the Siemenssales organization worldwide. Availability andpackaging may vary by country and is subjectto change without prior notice. Some/All ofthe features and products described herein maynot be available in the United States.The information in this document containsgeneral technical descriptions of specificationsand options as well as standard and optionalfeatures which do not always have to be presentin individual cases.Siemens reserves the right to modify the design,packaging, specifications and options describedherein without prior notice.Please contact your local Siemens salesrepresentative for the most current information.Note: Any technical data contained in thisdocument may vary within defined tolerances.Original images always lose a certain amountof detail when reproduced.www.siemens.com/healthcare-magazineGlobal Business UnitSiemens AGMedical SolutionsMagnetic ResonanceHenkestr. 127DE-91052 ErlangenGermanyPhone: +49 9131 84-0www.siemens.com/healthcareLocal Contact InformationAsiaSiemens Pte LtdThe Siemens Center60 MacPherson RoadSingapore 348615Phone: +65 6490-8096CanadaSiemens Canada LimitedMedical Solutions2185 Derry Road WestMississauga ON L5N 7A6CanadaPhone: +1 905 819-5800Europe/Africa/Middle EastSiemens AGMedical SolutionsHenkestr. 12791052 ErlangenGermanyPhone: +49 9131 84-0Latin AmericaSiemens S.A.Medical SolutionsAvenida de Pte. Julio A. Roca No 516,Piso 7C1067ABN Buenos AiresArgentinaPhone: +54 11 4340-8400USASiemens Medical Solutions U.S.A., Inc.51 Valley Stream ParkwayMalvern, PA 19355-1406USAPhone: +1-888-826-9702Global SiemensHealthcare HeadquartersSiemens AGHealthcare SectorHenkestrasse 12791052 ErlangenGermanyPhone: +49 9131 84-0www.siemens.com/healthcareGlobal Siemens HeadquartersSiemens AGWittelsbacherplatz 280333 MuenchenGermanyOrder No. A91MR-1000-87C-7600 | Printed in Germany | CC 170 111230. | © 11.12, Siemens AGk Visit www.siemens.com/magnetom-worldfor case reports,clinical methods,application tips,talks and much moreclinical information. The Magazine of MRIIssue Number 2/2012RSNA EditionMAGNETOM Flash
  2. 2. ImprintMAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 107Yes,IconsenttotheaboveinformationbeingusedforfuturecontactregardingproductupdatesandotherimportantnewsfromSiemens.Please print clearly!SubscriptionunsubscribefrominfoserviceStayuptodatewiththelatestinformationRegisterfor:PleaseenteryourbusinessaddressInstitutionDepartmentFunctionTitleNameStreetPostalCodeCityStateCountryMRsystemusedE-mailPleaseincludemeinyourmailinglistforthefollowingSiemensHealthcarecustomermagazine(s):MedicalSolutionsMAGNETOMFlashSOMATOMSessionsAXIOMInnovations2 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldEditorialJohn A. Carrino, M.D., M.P.H.Associate Professor of Radiology andOrthopedic SurgerySection Chief, Musculoskeletal RadiologyThe Russel H. Morgan Department ofRadiology and Radiological ScienceJohns Hopkins UniversitySchool of MedicineBaltimore, Maryland, USADear MAGNETOM users,IIt is truly an honor and a privilege for me to edit this2012 RSNA edition of MAGNETOM Flash. This issuefocuses on the imaging of musculoskeletal diseases/disorders – a substantial source of morbidity world-wide. Without any radiation, MR imaging depictsoccult bone injuries and soft tissue, such as meniscal,ligament and tendon tears with unparalleled tissuecontrast. Providers who are eager for advanceddiagnostic and therapeutic techniques to preventend-stage joint damage and preserve quality of lifewill find a good variety of technical, experiential andclinical information available in this issue spanningthe spectrum of bone, joint and soft tissue topics.The variety of musculoskeletal anatomy at numerouslocations throughout the body lends itself to 3Dimaging. The orientation of many articulations andadjacent supporting soft tissue structures are notin the traditional cardinal planes and can be difficultto evaluate with routine coronal, axial and sagittalsections. 3D imaging using SPACE1empowers theuser to create arbitrary multi-planar reconstructionsin the contrasts that are best suited for musculo-skeletal imaging. Furthermore, whilst MR imagingcan be limited by metal artifact for post-operativepatients, the development of new techniquesencompassed in syngo WARP1reduces the suscep-tibility effects and signal pile ups to produce animproved visualization of peri-implant complications.Exciting developments in this area include:• Cartilage imaging – the ‘holy grail’ to an under-standing of joint internal derangement. Highspatial resolution is key for morphological tasks.However, an ability to probe the biochemicalmilieu of chondroid matrix can reveal early degener-ation for pre-structural changes of arthritis andregeneration of normal cartilage constituents afterbiological repair.2• Oncology applications – diffusion-weighted imagingshows an increased potential for differentiatingbenign from malignant processes based on restricteddiffusion [1]. The ability for time-effective whole-body acquisition now means that MRI can rival othertechniques for total disease surveillance.• Increased signal-to-noise ratio (SNR) through (a)high field strength to acquire improved spatial, con-trast, temporal or spectral resolution to better depictinfrastructural details, gain a more direct evaluationof sodium present within cartilage, capture real-time kinematic joint motion as for cardiac imagingand improve the detection of smaller quantitymetabolites, and (b) the use of coils. For extremitywork we now have an increased number of chan-nels and extended field-of-view coils suitable forhigh resolution imaging of the entire foot and hand.• The application of MR protocols – greatly facilitatedby the workflow developed within Dot (day opti-mized throughput) engines.Special thanks to all our contributors. These con-tributions are a valuable resource to assist otherMAGNETOM users in making optimum use of theirsystems at the cutting edge of daily practice andto enhance the medical imaging objectives of visual-ization, recognition and interpretation.John A. Carrino, M.D., M.P.H.The entire editorial staff extends their appreciation toall the radiologists, technologists, physicists, expertsand scholars who donated their time and energy –without payment – in order to share their expertisewith the readers of MAGNETOM Flash.MAGNETOM Flash – Imprint© 2012 by Siemens AG,Berlin and Munich,All Rights ReservedPublisher:Siemens AGMedical SolutionsBusiness Unit Magnetic Resonance,Karl-Schall-Straße 6, D-91052 Erlangen,GermanyGuest Editor:John A. Carrino, M.D., M.P.H.Associate Professor of Radiology andOrthopedic Surgery, Section ChiefMusculoskeltal Radiology, Johns HopkinsUniversity School of Medicine, Baltimore,MD, USAAssociate Editor:Antje Hellwich(antje.hellwich@siemens.com)Editorial Board:John A. Carrino, M.D., M.P.H.;Antje Hellwich; Milind Dhamankar, M.D.;Ferdinand Lipps, Ph.D.; Wellesley Were;Ralph Strecker; Sunil Kumar, M.D.;Gary R. McNeal; Peter Kreisler, Ph.D.Production: Norbert Moser, Siemens AG,Medical Solutions, Erlangen, GermanyLayout: independent Medien-DesignWidenmayerstrasse 16, D-80538 Munich,GermanyPrinter: Mediahaus Biering GmbH,Freisinger Landstr. 21, 80939 Munich,GermanyNote in accordance with § 33 Para.1 ofthe German Federal Data Protection Law:Despatch is made using an address filewhich is maintained with the aid of anautomated data processing system.MAGNETOM Flash with a total circulationof 35,000 copies is sent free of chargeto Siemens MR customers, qualified phy-sicians, technologists, physicists andradiology departments throughout theworld. It includes reports in the Englishlanguage on magnetic resonance:diagnostic and therapeutic methods andtheir application as well as results andexperience gained with correspondingsystems and solutions. It introduces fromcase to case new principles and proce-dures and discusses their clinical poten-tial.The statements and views of the authorsin the individual contributions do notnecessarily reflect the opinion of thepublisher.The information presented in thesearticles and case reports is for illustrationonly and is not intended to be reliedupon by the reader for instruction as tothe practice of medicine. Any health carepractitioner reading this information isreminded that they must use their ownlearning, training and expertise in deal-ing with their individual patients. Thismaterial does not substitute for that dutyand is not intended by Siemens MedicalSolutions to be used for any purposein that regard. The drugs and dosesmentioned herein are consistent withthe approval labeling for uses and/orindications of the drug. The treatingphysician bears the sole responsibility forthe diagnosis and treatment of patients,including drugs and doses prescribed inconnection with such use. The OperatingInstructions must always be strictlyfollowed when operating the MR system.The sources for the technical data are thecorresponding data sheets. Results mayvary.Partial reproduction in printed form ofindividual contributions is permitted,provided the customary bibliographicaldata such as author’s name and title ofthe contribution as well as year, issuenumber and pages of MAGNETOM Flashare named, but the editors request thattwo copies be sent to them. The writtenconsent of the authors and publisher isrequired for the complete reprinting ofan article.We welcome your questions and com-ments about the editorial content ofMAGNETOM Flash. Please contact us atmagnetomworld.med@siemens.com.Manuscripts as well as suggestions,proposals and information are alwayswelcome; they are carefully examinedand submitted to the editorial board forattention. MAGNETOM Flash is notresponsible for loss, damage, or any otherinjury to unsolicited manuscripts or othermaterials. We reserve the right to editfor clarity, accuracy, and space. Includeyour name, address, and phone numberand send to the editors, address above.MAGNETOM Flash is also available on the internet:www.siemens.com/magnetom-world[1] Spuentrup E, Buecker A, Adam G, van Vaals JJ, Guenther R W. Diffusion-weighted MR imaging for differentiation of benign fracture edemaand tumor infiltration of the vertebral body. Am J Roentgenol 2001; 176(2):351 - 381.1The software is pending 510(k) clearance, and is not yet commercially available in the United States.2A licensed physician may choose to ause FDA-approved contrast agents in conjunction with an MRI examination, based on his/hermedical opinion and discretion and in accordance with the instructions for use and indication for use supplied by the pharmaceuticalmanufacturer for the contrast agents.
  3. 3. EditorialMilind Dhamankar, M.D.Sr. Director, MR ProductMarketing, Malvern, PA, USAEditorial BoardWe appreciate your comments.Please contact us at magnetomworld.med@siemens.comReview BoardLisa Chua, Ph.D., Clinical Collaboration ManagerWilhelm Horger, Application Development OncologyMichelle Kessler, US Installed Base ManagerBerthold Kiefer, Ph.D., Oncological and Interventional ApplicationsFerdinand Lipps, Ph.D., Global Marketing Manager OrthopedicsHeiko Meyer, Ph.D., Neuro ApplicationsSilke Quick, Global Marketing Manager Women’s HealthRaphael Schwarz, Ph.D., Orthopedic ApplicationsIgnacio Vallines, Ph.D., Global Marketing Manager NeurologyHeike Weh, Clinical Data ManagerSven Zühlsdorff, Clinical Collaboration ManagerAntje HellwichAssociate EditorDr. Sunil Kumar S.L.Senior Manager Applications,Mississauga, ON, CanadaRalph StreckerMR Collaboration Manager,São Paulo, BrazilChristiane BernhardtHead Outbound MarketingErlangen, GermanyWellesley WereMR Business DevelopmentManager Australia and NewZealandGary R. McNeal, MS (BME)Advanced Application Specialist,Cardiovascular MR ImagingHoffman Estates, IL, USAPeter Kreisler, Ph.D.Collaborations & Applications,Erlangen, GermanyMAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 3
  4. 4. EditorialMilind Dhamankar, M.D.Sr. Director, MR ProductMarketing, Malvern, PA, USAEditorial BoardWe appreciate your comments.Please contact us at magnetomworld.med@siemens.comReview BoardLisa Chua, Ph.D., Clinical Collaboration ManagerWilhelm Horger, Application Development OncologyMichelle Kessler, US Installed Base ManagerBerthold Kiefer, Ph.D., Oncological and Interventional ApplicationsFerdinand Lipps, Ph.D., Global Marketing Manager OrthopedicsHeiko Meyer, Ph.D., Neuro ApplicationsSilke Quick, Global Marketing Manager Women’s HealthRaphael Schwarz, Ph.D., Orthopedic ApplicationsIgnacio Vallines, Ph.D., Global Marketing Manager NeurologyHeike Weh, Clinical Data ManagerSven Zühlsdorff, Clinical Collaboration ManagerAntje HellwichAssociate EditorDr. Sunil Kumar S.L.Senior Manager Applications,Mississauga, ON, CanadaRalph StreckerMR Collaboration Manager,São Paulo, BrazilChristiane BernhardtHead Outbound MarketingErlangen, GermanyWellesley WereMR Business DevelopmentManager Australia and NewZealandGary R. McNeal, MS (BME)Advanced Application Specialist,Cardiovascular MR ImagingHoffman Estates, IL, USAPeter Kreisler, Ph.D.Collaborations & Applications,Erlangen, GermanyMAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 3
  5. 5. Clinical 3D Imagingand ArtifactReduction6 3D Musculoskeletal MRI withsyngo SPACEMike Notohamiprodjo12 Imaging of Metallic ProsthesesUsing Novel SequencesLeon Rybak, et al.20 Experience with the MAGNETOMVerio system in Spine Imaging:Benefit of 3D Sequences andReduction of Metal-Related Artifactswith syngo WARP1Marcel Wolf, Marc-André WeberProduct News24 syngo WARP1: Metal Artifact ReductionTechniques in MRITheresa Bachschmidt, et al.ClinicalCartilage Imaging26 MRI Assessment of ArticularCartilage RepairDarshana SanghviThe information presented in MAGNETOM Flash is for illustration only and is notintended to be relied upon by the reader for instruction as to the practice of medicine.Any health care practitioner reading this information is reminded that they must usetheir own learning, training and expertise in dealing with their individual patients. Thismaterial does not substitute for that duty and is not intended by Siemens MedicalSolutions to be used for any purpose in that regard. The treating physician bears the soleresponsibility for the diagnosis and treatment of patients, including drugs and dosesprescribed in connection with such use. The Operating Instructions must always bestrictly followed when operating the MR System. The source for the technical data is thecorresponding data sheets.MR scanning has not been established as safe for imaging fetuses and infants undertwo years of age. The responsible physician must evaluate the benefit of the MRIexamination in comparison to other imaging procedures.The MRI restrictions (if any) of the metal implant must be considered prior to patientundergoing MRI exam. MR imaging of patients with metallic implants brings specificrisks. However, certain implants are approved by the governing regulatory bodies to beMR conditionally safe. For such implants, the previously mentioned warning may notbe applicable. Please contact the implant manufacturer for the specific conditional infor-mation. The conditions for MR safety are the responsibility of the implant manufacturer,not of Siemens.ContentWith the first issuepublished in 1993 we nowcelebrate issue number 50.From the very beginningMAGNETOM Flash was acooperation of SiemensHealthcare with MAGNETOMusers.We welcome your feedback,questions and comments –please contact us atmagnetomworld.med@siemens.com4 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldContent 12syngo WARP150Bone and Soft Tissue Tumor Imaging
  6. 6. ContentClinical Oncology50 Bone and Soft Tissue TumorImagingMarcus Pianta, et al.58 How I do itMSK Imaging Tips & TricksMark Lourensz, et al.60 Whole-Body Diffusion-WeightedMRI of the Bone Marrow in Healthand DiseaseAnwar Padhani, et al.66 Knee MR Imaging of an Osteo-chondroma in Combination withMelorheostosisPaul Flechsig, Marc André WeberClinicalPediatric Imaging70 Sinding-Larsen-Johansson DiseaseAxel Goldmann72 MRI of the Fetal Skeleton.Tips for Sequence Parametersand Post-Processing ProtocolMarcio Bernardes, et al.TechnologyTissue Function74 Implementation of QuantitativeMRI Evaluation of Tissue Healthinto Clinical PracticeCharles P. Ho, et al.80 T1ρ MRI: A Potential Biomarkerof Cartilage PhysiologyArijitt Borthakur, et al.86 Biochemical MR in MusculoskeletalApplicationsSiegfried Trattnig, et al.TechnologyImage Gallery98 Ultra High Field (7 Tesla*) MRIfor Musculoskeletal ApplicationsSiegfried Trattnig, et al.Clinical Sports andTrauma Imaging30 Case Series Sports and Trauma Imagingincluding:- Chondral Delamination in the Knee- Melorheostosis- Glenohumeral Joint DislocationEric K. Fitzcharles, Charles P. HoClinical Case Report42 Job’s SyndromeG. Hadjidekov, et al.How I do it46 MRI of the Shoulder: Utilizingthe Glenoid Clockface OrientationSteven D. NeedellMAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 560Whold-Body DWI86Biochemical MRI987T* MR Na+imaging*The 7T system is a research system only.It cannot be used outside of a research study.1syngo WARP and syngo RESOLVE are pending510(k) clearance. The software is not yetcommercially available in the United States andin other countries.
  7. 7. 6 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical 3D ImagingBackgroundDue to the excellent soft-tissue contrastMRI is the primary modality in musculo-skeletal (MSK) imaging. It offers excel-lent direct depiction of bone marrow,Three-Dimensional Musculoskeletal MRImaging with syngo SPACEMike Notohamiprodjo, M.D.Department of Clinical Radiology, University Hospitals Munich, Munich, Germanyfibrous, ligamentous and cartilaginousstructures as well as of the periarticularsoft tissue. However, many anatomicalstructures such as ligaments and ten-dons are obliquely oriented. These struc-tures and lesions / signal alterations arehence difficult to assess with two-dimensional (2D) sequences oriented inthe standard planes. At a standard slicethickness of 3–5 mm [1], depiction is1 Subtle III°-cartilage defect of the dorsal lateral femoral condyle.Left knee of a 52-year-old female patient: The cartilage defect is mostly obscured and was missed in the 2D TSE reading (upper row, arrow)because of partial volume effects. While only visible on 1 2D FSE slice, the defect is clearly visible in syngo SPACE (bottom row).(With permission from [8].)1syngo SPACE
  8. 8. MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 73D Imaging Clinicalalso often comprised by partial volumeeffects, which may mimic signal altera-tion. Three-dimensional (3D) reconstruc-tions of the standard planes are an alter-native to additional sequences [2],although image quality is limited due tothe anisotropic voxel-dimensions andinterslice gaps of conventional 2Dsequences. Acquisition of an isotropicsource-dataset reducing partial volumeeffects and eliminating interslice gaps istherefore desirable and has been shownfeasible and useful in previous studies[3–9]. Anatomical understanding anddepiction of small lesions may particu-larly benefit from this approach.Multi-channel extremity coils and higherfield strengths facilitate time-efficientacquisition and allow to acquire isotropic3D Turbo Spin Echo (TSE) sequences[10, 11], such as syngo SPACE (SamplingPerfection with Application optimizedContrasts using different flip angle Evo-lutions). With these 3D sequences, thewhole area of interest is covered by anisotropic volume, which can be subse-quently reconstructed in any desired ori-entation and slice thickness. Such a pri-mary 3D approach for MSK imaging hasbeen performed in several studies with aT2 or Proton Density-weighted 3D TSEsequence [7–9]. However, a T1-weighted(T1w) contrast is still required for a com-prehensive MSK protocol. This articledemonstrates our experiences withsyngo SPACE in musculoskeletal MRexaminations, also in combination witha T1-weighted protocol.Technical considerationsAn exemplary isotropic syngo SPACE-protocol is provided in Table 1. The 3Dblocks cover the whole area of interest,so that exact orientation along impor-tant anatomical structures, e.g. thesupraspinatus tendon or anterior cruci-ate ligament, is not required with theseisotropic sequences [8]. The acquisitiontime of 3D sequences would have to bethe same or at least similar to conven-tional 2D sequences, so that implemen-tation of these sequences is justifiable.The compromise between acquisitionTR = repetition time; TE = echo time; FA = flip angle; FOV = field-of-view;PAT = parallel acquisition technique (GRAPPA).Table 1: Sequence parametersParameter T1w syngo SPACE T2w syngo SPACEOrientation Coronal CoronalTR (ms) 700 1100TE (ms) 26 37FA (°) 130 120-100-80Matrix 230 x 230 256 x 256FOV (mm) 160 x 160 160 x 160Slice thickness (mm) 0.6 0.6Number of slices (n=) 120 120Bandwidth (Hz/pixel) 543 430Echo train length 142 30PAT (R=) 2 3Number of averages 1 1Acquisition time(min)6:24 6:43time and image quality is fundamentalto all MRI approaches, and 3D TSE tech-niques have been struggling with eitherlong acquisition times or low resolution.Longer acquisition times improve imagequality but increase the susceptibility formotion artifacts. To shorten acquisitiontime we have performed parallel imag-ing with the k-space based techniquesyngo GRAPPA. The average examinationtime was 6–10 minutes per sequencedepending on the organ of interest andthe size of the joint [7–9]. This isapproximately 2–5 minutes longer thanthe acquisition of a single conventionalansisotropic 2D sequence but still con-siderably faster than acquisition ofthree separate sequences. We observedmotion artifacts similarly in both con-ventional and 3D sequences [7–9].Compared to Gradient Echo sequencesmetal artifacts did not negatively affectimage quality.The isotropic resolution of syngo SPACEallows for free arbitrary online recon-struction. However, because of signal-
  9. 9. related constraints or missing 3D recon-struction abilities of the PACS system,several previous studies featured time-consuming, standardized, retrospectivereconstructions of the isotropic sourcedata set in thicker slices, sacrificing themajor asset of this sequence technique[3, 8]. Radial k-space acquisition andelliptical scanning were recently intro-duced in syngo SPACE, so that it pro-vides excellent signal and contrast [7,9]. In our department we now use theonline 3D reconstruction capabilities ofthe PACS-integrated imaging softwaresyngo.via to assess the original 3D data-set, so that no additional reconstructiontime is required [9].Clinical applicationWe primarily use syngo SPACE protocolsat 3T (MAGNETOM Verio, SiemensHealthcare, Erlangen, Germany) in com-bination with dedicated multi-channelcoils for the MRI-examination of joints,such as the knee, shoulder and ankle,but also for the assessment of bone mar-row changes of the jaw (here only T1w).In previously published studies we haveshown that a moderately T2-weightedsequence is feasible for time-efficientisotropic assessment of the knee andankle [7-9]. In the knee, syngo SPACEhas been shown superior to conven-tional 2D sequences for the depiction ofthe cartilage of the femoral trochlea andthe meniscus root ligaments [7, 8].Small lesions of femoral trochlea orperipheral condyles or talus can be read-ily depicted with syngo SPACE with ahigher diagnostic confidence than forconventional sequence (Fig. 1). How-ever, a small additional number of carti-lage and meniscus lesions were detectedwith syngo SPACE, which was mainlyattributed to a reduction of through-plane partial volume effects. Sensitivityfor meniscus lesions was higher forsyngo SPACE compared to conventional2D sequences (Fig. 2).The ankle is one of the most complexhuman joints and most ligaments andtendons are oriented obliquely, so that8 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical 3D Imaging2 III°-lesion of the dorsal portion of the medial meniscus.Left knee of a 21-year-old female patient: The III°-tear of the dorsal portion of themedial meniscus is clearly visible in syngo SPACE (bottom row). The involvement ofthe meniscus surface is obscured in 2D TSE (upper row) and was regarded as a II°degeneration. (With permission from [8].)syngo SPACE22D TSE
  10. 10. syngo SPACE appears particularly prom-ising. Indeed syngo SPACE was superiorto 2D sequences for the depiction of thespheric tibial and talar cartilage (Fig. 4)as well as for the spring ligament com-plex. The complete three-dimensionalapproach facilitated good depiction ofthose ligaments usually difficult toassess with standard 2D sequences. Noabnormality detected with conventional2D TSE was missed when using syngoSPACE and intersequence- and inter-reader correlation showed no significantdifferences, so that implementation ofsyngo SPACE in clinical routine protocolsappears justified [9].A T1-weighted 3D approach appearsparticularly promising to achieve a com-plete 3D protocol. Our first results showthat T1w syngo SPACE yields a very simi-lar contrast to conventional 2D SEsequences, so that a need for any signifi-cant adjustment of the radiologist’sreading and interpretation habits to thenew sequence is unlikely. Assessment oftendons and the subchondral bone isreadily possible with T1w syngo SPACE.The T1w contrast allows for an improvedanatomical understanding and is usefulfor verification of findings in the T2wsequence (Fig. 5). The anatomicallycomplex jaw appears particularly prom-ising for the application of the T1wsequence. T1w sequences show thehighest sensitivity for diseases affectingthe structures of the bone, which arecommonly found in the jaw bone [12].The isotropic resolution allows for a con-venient analysis of the jaw bone, evenwith curved multiplanar reconstructions(MPRs) very similar to an orthopantomo-gram (Fig. 6).ConclusionIsotropic 3D imaging with syngo SPACEis a promising approach to assess mus-culoskeletal pathologies. Previous tech-nical constraints such as low SNR, CNRand blurring have been compensated byflip angle optimization and radialMAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 93D Imaging Clinicalsyngo SPACE 2D TSE3 Osteochondral abnormalities. A small osteochondral lesion of the medial tibia can be clearly delineated in syngo SPACE (arrow). In the 2DTSE sequence the discontinuity of the subchondral bone cannot be detected. Depiction of bone marrow edema is similar in both sequences.(With permission from [9]).3
  11. 11. 10 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical 3D Imaging4 Combined T1w and T2w syngo SPACE dataset of the shoulder.T1w and moderately T2w syngo SPACE can be combined for a comprehensive 3D protocol. Right shoulder of a 45-year-old male patient:Small partial tear of the supraspinatus tendon (arrow). syngo SPACE provides excellent contrast between joint fluid and tendons/muscle.5 Luxation of the biceps tendon.46-year-old male patient with tear of the subscapularis muscle and consecutive anteromedial luxation of the biceps tendon (arrows).The biceps sulcus is empty (dotted arrow) syngo SPACE allows to conveniently display the full course of the tendon in one slice.45syngo SPACEsyngo SPACE
  12. 12. References1 Resnick, D., H.S. Kang, and M.L. Pretterklieber,Internal derangements of joints. 2nd ed2006,Philadelphia: Saunders/Elsevier. 2 v. (xvi, 2284,liv p.).2 Duc, S.R., et al., Improved visualization of collat-eral ligaments of the ankle: multiplanar recon-structions based on standard 2D turbo spin-echoMR images. Eur Radiol, 2007. 17(5): p. 1162-71.3 Gold, G.E., et al., Isotropic MRI of the kneewith 3D fast spin-echo extended echo-trainacquisition (XETA): initial experience. AJR Am JRoentgenol, 2007. 188(5): p. 1287-93.4 Gold, G.E., et al., Balanced SSFP imaging of themusculoskeletal system. J Magn Reson Imaging,2007. 25(2): p. 270-8.5 Kijowski, R., et al., Vastly undersampled isotro-pic projection steady-state free precessionimaging of the knee: diagnostic performancecompared with conventional MR. Radiology,2009. 251(1): p. 185-94.6 Kijowski, R., et al., Knee joint: comprehensiveassessment with 3D isotropic resolution fastspin-echo MR imaging--diagnostic performancecompared with that of conventional MR imagingat 3.0 T. Radiology, 2009. 252(2): p. 486-95.7 Notohamiprodjo, M., et al., 3D-imaging of theknee with an optimized 3D-FSE-sequence anda 15-channel knee-coil. European journal ofradiology, 2012.8 Notohamiprodjo, M., et al., MRI of the knee at 3T:first clinical results with an isotropic PDfs-weighted 3D-TSE-sequence. Investigativeradiology, 2009. 44(9): p. 585-97.MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 113D Imaging ClinicalContactMike Notohamiprodjo, M.D.Section Chief Conventional RadiologyDepartment of Clinical RadiologyUniversity Hospitals MunichCampus GroßhadernMarchioninistrasse 1581377 MunichGermanyPhone: +49-89-7095-3620Fax: +49-89-7095-8832mike.notohhamiprodjo@med.lmu.de6 Curved MPR of the jaw.62-year-old female patient with osteonecrosis of the jaw. A curved MPR along the oral midline was created to display the mandible andmaxilla in one slice. The large osteonecrosis of the right mandibular ramus (arrows) can be readily depicted in this T1w syngo SPACE sequence.k-space sampling. The theoretical sus-ceptibility of this technique to motionartifacts did not become evident in ourexperience. The identification of ana-tomical structures at least equals theconventional sequence and allows supe-rior discrimination of relevant smallligamentous and cartilaginous struc-tures. The image contrast is comparableto conventional 2D sequences, so thatno considerable adjustment by theradiologist is necessary.A combined isotropic T1w and moder-ately T2w 3D protocol will take approxi-mately 12–16 minutes. In combinationwith arbitrary multiplanar reformation,no other additional sequences arenecessary. Therefore, syngo SPACE hasbecome an appropriate alternative forsubstantially shortened routine MSKprotocols.9 Notohamiprodjo, M., et al., 3D-MRI of theankle with optimized 3D-SPACE. Investigativeradiology, 2012. 47(4): p. 231-9.10 Alsop, D.C., The sensitivity of low flip angleRARE imaging. Magn Reson Med, 1997. 37(2):p. 176-84.11 Hennig, J., Multiecho imaging sequences withlow refocusing flip angles. J Magn Reson., 1988.1988(78): p. 397-407.12 Arce, K., et al., Imaging findings in bisphospho-nate-related osteonecrosis of jaws. Journal oforal and maxillofacial surgery : official journal ofthe American Association of Oral and Maxillofa-cial Surgeons, 2009. 67(5 Suppl): p. 75-84.6syngo SPACE
  13. 13. 12 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Artifact ReductionImaging of Metallic Prostheses UsingNovel Sequences: Early ExperienceLeon D. Rybak, M.D.1; Mary Bruno, B.S.1; Mathias Nittka, Ph.D.2; Christian Geppert, Ph.D.3; Holly Delaney, M.D.1;Park Jong, M.D.11New York University Medical Center, Department of Radiology, New York, NY, USA2Siemens Healthcare, Erlangen, Germany3Siemens US R&D Collaborations, New York, NY, USAIntroductionFor many years, diagnostic imaging inpatients with metallic implants had beenlimited to plain X-rays and nuclear medi-cine studies. Although there have beenadvancements with regards to imagingof hardware using computed tomogra-phy, many of the changes involveincreasing the radiation dose at a timewhen the public has become increas-ingly sensitive to reported long term riskof carcinogenesis posed by this expo-sure. With recent technical develop-ments, magnetic resonance imaging(MRI) in the presence of metal is quicklybecoming a reality with the added bene-fits of excellent soft tissue resolutionand contrast. This could not come ata better time considering that newmethods of hip and knee arthroplastyhave led to unique complications whichrequire timely diagnosis and treatmentto prevent implant failure, damage tothe surrounding soft tissues and, possi-bly, carcinogenesis [1, 2]. This articleoutlines some of these advances anddescribes the author’s early experiencesin regards to the clinical use of thesetechniques.The clinical incentiveInitial attempts at arthroplasty involvedthe interposition of various substancesincluding fascia lata, porcine bladder,gold foil, glass, rubber and Vitallium[3–5]. Early versions of hip arthroplas-ties were marred by flawed design andpoor materials resulting in early failure.It was not until the 1960s that Sir JohnCharnley of the Manchester Royal Infir-mary developed the initial prototype ofwhat would become a long line of mod-ern hip arthroplasties. It soon becameapparent, however, that the longevity ofthese devices was limited, in large partto wear of the various components. Itwas also discovered that the particleswhich resulted from this wear couldincite an inflammatory response thatled to areas of bone destruction. Thisprocess was given several names overthe years, some of which included‘cement disease’, ‘particle disease’,‘foreign body granuloma formation’ or,simply, ‘osteolysis’ [6, 7]. Although mostcases were limited, more florid casesresulting in widespread and extensivebone loss were noted. This ‘aseptic’ formof loosening which, though not withoutconsequence, would have to be differ-entiated from septic or infectious loos-ening. Infected arthroplasties, requireremoval and, in many cases, a twostaged procedure with a period of anti-biotic therapy prior to re-implantation.Though the gold standard in thesecases has remained joint aspiration andculture, imaging has played a role withcertain plain film findings and nuclearimaging studies helping to confirm thediagnosis.Initial reports of osteolysis around artho-plasties implicated methacrylate (cement)as the inciting factor. However, with theadvent of non-cemented components,the majority of cases have been attrib-uted to wear of the polyethylene compo-nents [6]. Regardless of the presence ofbone destruction, the inevitable loss ofthe polythene weight-bearing surfaceshas led to a limited lifespan of the pros-thesis and the need for revision surgery.In an effort to increase the longevityof the components, much research hascentered on the creation of new, moredurable plastics included cross-linkedultrahigh-molecular-weight polyethyleneas well as the use of other substancessuch as ceramic [4, 5]. Though initiallyexplored in the 1960s, metal-on-metalsystems had not met with success andwere abandoned. In an effort to preventthe complications resulting from com-ponent wear, the feasibility of such asystem was revisited in the past decade.Theoretically, metal-on-metal systemswould eliminate the need for plasticaltogether, reduce the rate of wear andallow for the use of larger femoral headsproviding for greater stability and rangeof motion [5] (Fig. 1). Though thesenew systems showed early promise, theyhave created a new set of problems andcomplications. Metal wear resulting in‘metallosis’ with elevated blood levels ofions has been noted, creating a fear ofpossible carcinogenesis [1, 2]. Morerecently, a new form of perivascular lym-phocytic infiltration involving the softtissues of the hip girdle referred to asaseptic lymphocyte-dominated vasculi-tis-associated lesions (ALVAL), has beendescribed [8–13]. In addition to areas ofosteolysis, this pathologic entity hasbeen noted to manifest as synovitis,peri-prosthetic soft tissue masses andbursal fluid collections. Like osteolysis,ALVAL needs to be discriminated and haseven been implicated as a risk factor forinfection [14, 15].
  14. 14. MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 13Artifact Reduction ClinicalThese developments have created anadditional incentive to find a safe andeffective mechanism of non-invasivelyevaluating both the prosthetic compo-nents themselves, but also the jointspace and surrounding soft tissues.Recent advances in magnetic resonanceimaging have made this possible.The physicsIn order to be able to fix a problem, onemust first be familiar with the issues.When a patient with an arthroplasty isplaced in the magnetic field, the rela-tively easily magnetized metallic com-ponents of the arthroplasty are in directapposition to poorly magnetized softtissues creating large localized fluctua-tions of the static magnetic field. Theresult is either spatial mismapping oreven complete signal loss. One shouldbe aware that the mismapping takesplace in two dimensions: one is thein-plane signal misregistration in thefrequency direction which occurs duringreadout, closely related to the wellknown chemical shift effect. The secondeffect is a through-plane distortion dueto warping that occurs at the time ofslice selection. Metal artifacts arestrongly dependent on the type andshape of the metal used and the orien-tation of the metal within the magneticfield. Titanium implants, being lessmagnetic, tend to pose the least problemfor the imager, with stainless steelcausing more perturbation of the fieldand cobalt chrome presenting thegreatest challenge. As the susceptibilityartifact occurs in the frequency direc-tion, orienting the metallic componentswith the longest axis in the frequencydirection will allow optimal resolution ofchanges along the greatest proportionof the metal soft tissue interface. Alter-natively, two acquisitions with a swap ofphase and frequency will optimize reso-lution around all portions of the pros-thetic components. Finally, curved orrounded portions of the metal compo-nents like the femoral head tend to1 AP radiographs of the hip in the same patient before (1A) and after (1B) revision arthroplasty. The original prosthesis in (1A)consists of a metal on metal device with no interposed plastic component. Note the large size of the metallic femoral headwhich articulates directly with the acetabular cup. In the more traditional revised prosthesis in (1B), note the lucent zone (arrow)between the femoral head and acetabulum which reflects the interposed polyethylene liner.1A 1B
  15. 15. 14 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Artifact Reduction2 STIR contrast images of a total knee prosthesis in the sagittal plane (2A, 2B) and a total hip prosthesis in the coronal plane(2C, 2D) obtained on a 1.5T magnet (MAGNETOM Avanto, Siemens Healthcare). In each case, the left sided image was obtainedwith routine technique and the right image, with the SEMAC* sequence. The imaging times were between 3–4.5 minutes for theconventional and 9–12 minutes for the SEMAC sequences. Arrow pointing to the lateral soft tissue.2A 2B2C 2D
  16. 16. cause more disturbance of the magneticfield than the linear portions [16–20].It is, thus, possible to eliminate a certainamount of artifact making changes inseveral of the basic sequence parame-ters. First, turbo spin echo (TSE) tech-niques are used to take advantage of themultiple 180 degree refocusing pulseswhich result in rephasing of the signal.Second, receiver bandwidth is increasedto reduce the shift in the frequencyencoding direction in the area of themetal. Third, spatial resolution isincreased by using a finer matrix todecrease the conspicuity of the artifact.Last, if fat suppression is required, inver-sion recovery is favored over frequencyselective techniques which may suffer asa result of field inhomogeneity.In addition, there are more sophisticatedapproaches to metal reduction whichchange the actual acquisition scheme ofthe conventional TSE sequence. One ofthese which is referred to as view angletilting* (VAT) involves applying an addi-tional readout gradient with the sameamplitude as that employed during sliceselect, thereby re-phasing the spins inthe x-axis and correcting for in-planedistortion [21]. Slice Encoding for MetalArtifact Reduction1(SEMAC) is a noveltechnique which is presently beingtested for clinical applications. WithSEMAC, additional phase encoding stepsare applied in the z-direction, correctingthrough plane distortions. This methodis used in conjunction with VAT [22, 23].Though artifact reduction has beendemonstrated, there is a significant timecost with SEMAC and much of theresearch at this time is focused onincreasing the speed of image acquisi-tion with this technique.Early clinical resultsSeveral groups using various methods ofmetal reduction have reported good toexcellent results in visualization of boththe prosthetic bone interface as wellas the surrounding soft tissue envelopein patients [20, 24, 25]. Using theirstandard protocol with simple parametermodifications designed for optimizationof metal artifact reduction, White et al.3 1.5T MR images (MAGNETOM Avanto, Siemens Healthcare) from a surgi-cally proven case of metallosis with ALVAL status post metal on metal hipreplacement in a 48-year-old female. Both the optimized proton density-weighted image in the axial plane (3A) and the STIR image in the coronal planeusing SEMAC1(3B) demonstrate a large bilobed fluid-like collection extendingboth along the posterior joint margin (dashed blue arrow) as well as into theiliopsoas bursa anteriorly (solid blue arrow) with areas of low signal internaldebris. This is the same patient whose plain films are depicted in figure 1.3A3B
  17. 17. reported on MRI of 14 total hip arthro-plasties and found depiction of the peri-prosthetic structures to be of diagnosticquality for all of the femoral compo-nents and 36% of the acetabular compo-nents [20]. They found abnormalities in11 cases and correctly diagnosed pathol-ogy in all 7 cases in which surgical corre-lation was available. Potter et al., usinga similar technique, found good delinea-tion of the bone-implant interface andsurrounding soft tissues in 100% of 284 1.5T images(MAGNETOMAera, SiemensHealthcare) ofthe same hipprosthesisobtained in thecoronal planeusing protondensity (4A, B)and STIR (4C, D)contrast. Inboth cases, theimage on theleft is obtainedwith traditionalnon-optimizedtechnique andthat on the rightwith the WARP*sequences withVAT employed.Note the signifi-cant reductionof artifact usingthe WARP tech-nique, particu-larly along theacetabular com-ponent. Theincreased band-width of theWARP sequenceleads to theincreased noiselevel.4A 4B4C 4Dhip prostheses and correctly diagnosedareas of osteolysis in 15 patients withsurgical correlation.The NYU experienceAt NYU, between August of 2011 andAugust of 2012, we imaged 39 conse-cutive patients with painful hip (28 hipsin 29 patients) and knee (11 knees in10 patients) prostheses. Early in ourexperience, we used a combination ofroutine, routine optimized for metalreduction, VAT only and SEMAC1sequences, the latter two being a proto-type provided by Siemens (WARPWIP#648, works in progress package*).All patients were imaged on the same1.5 Tesla magnet (MAGNETOM Avanto,Siemens Healthcare, Erlangen, Ger-many). There was significant reductionof metal artifact both with the use of theoptimized and VAT only sequences inscan times comparable to those used inroutine imaging studies. The best result16 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Artifact Reduction
  18. 18. using STIR contrast was with SEMAC ata time cost. An example of the conven-tional and SEMAC sequences using STIRcontrast in a hip and knee in two differ-ent patients is provided in figure 2.Our clinical results were similarlyencouraging with significant findingsdiagnosed in 26 of the 39 cases andconfirmation of the findings in all 11cases with surgical correlation. Thesesurgically confirmed findings included5 cases of metallosis/ALVAL, 2 casesof patellar tendon rupture, 1 case of aninfected bursal collection, 1 case ofpatellar component loosening, 1 case ofacetabular osteolysis from polyethylenewear and 1 case of marked capsularthickening resulting in contracture ina knee. A case of metallosis/ALVAL isprovided in figure 3.More recently, we compared conven-tional imaging to syngo WARP*, an ‘outof the box’ optimized metal reductionsequence which can be used with orwithout the addition of VAT. Imagingwas performed at 1.5T (MAGNETOMAera, Siemens Healthcare, Erlangen,Germany). A side by side comparison ofconventional and syngo WARPsequences of the same hip prosthesis inthe coronal plane using proton density(Fig. 4A) and STIR (Fig. 4B) contrastsdemonstrates significant improvementin image quality with similar imagingtimes. The increased noise in the imagesis caused by the increased readout band-width.ConclusionExcellent reduction of metal artifact canbe achieved through the use of opti-mized traditional sequences as well asnovel techniques such as VAT andSEMAC1. At NYU, we have decided toadapt a protocol which consists of syngoWARP imaging with VAT obtained in allthree planes using a combination ofcontrasts suited to answering the partic-ular clinical questions being posed ineach case (Table 1). The SEMACsequence was used with STIR contrast inthe coronal plane in the hip and thesagittal plane in knees in patients whoappear to be able to tolerate the longerimaging time. Further enhancementsto the SEMAC sequence with reductionsin imaging time are being explored.MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 17Artifact Reduction ClinicalThe protocols we developed for hip and knee implants based on the new syngo WARP* sequence on 1.5T MAGNETOM Aera. Notethat all protocols apply VAT*, except for the axial hip, where the difference with or without VAT was not considered significant.Table 1: 1.5T MAGNETOM Aera protocols.TA[min]Ma-trixresolution[mm]FOV[mm]phaseencodingdirectionslices TR[ms]TE[ms]TI[ms]BW[Hz/Pixel]PATaccel.factorVAT turbofactorHip COR STIR 3:46 320 0.9x0.9x3.0 280 RL 36 4680 39 145 504 off on 17AX PD 5:29 320 0.7x0.7x3.0 220 AP 78 5450 31 521 off off 9COR PD 5:07 512 0.5x0.5x4.0 280 RL 28 5000 31 514 off on 33SAG PD 4:35 512 0.5x0.5x4.0 280 AP 40 4590 27 514 2 on 21Knee SAG STIR 3:42 384 0.5×0.5×3.0 200 HF 36 4800 45 150 383 off on 19AX PD 2:10 320 0.5×0.5×3.0 160 AP 58 5580 21 504 off on 12COR T1 1:34 320 0.6×0.6×4.0 200 RL 30 600 12 401 1 on 3SAG PD 2:18 448 0.4×0.4×4.0 200 HF 30 4000 25 558 off on 32*510(k) pending. Not for sale in the US and inother countries.1Works in Progress in the USA. The information about this product is preliminary. The product is under developmentand is not commercially available in the USA and its future availability cannot be ensured.
  19. 19. References1 Afolaranmi GA, Tettey J, Meek RM, Grant MH.Release of chromium from orthopaedicarthroplasties. The open orthopaedics journal.2008;2:10-18.2 Delaunay C, Petit I, Learmonth ID, Oger P,Vendittoli PA. Metal-on-metal bearings total hiparthroplasty: the cobalt and chromium ionsrelease concern. Orthopaedics & traumatology,surgery & research : OTSR. Dec 2010;96(8):894-904.3 Gomez PF, Morcuende JA. Early attempts athip arthroplasty--1700s to 1950s. The Iowaorthopaedic journal. 2005;25:25-29.4 Knight SR, Aujla, R., Biswas, S.P. Total Hip Arthro-plasty – over 100 years of operative history.Orthopedic Reviews. 2011;3:e16:72-74.5 Learmonth ID, Young C, Rorabeck C. The opera-tion of the century: total hip replacement.Lancet. Oct 27 2007;370(9597):1508-1519.6 Goodman S. Wear particulate and osteolysis.The Orthopedic clinics of North America.Jan 2005;36(1):41-48, vi.7 Kadoya Y, Kobayashi A, Ohashi H. Wear andosteolysis in total joint replacements. Actaorthopaedica Scandinavica. Supplementum.Feb 1998;278:1-16.8 Anderson H, Toms AP, Cahir JG, Goodwin RW,Wimhurst J, Nolan JF. Grading the severityof soft tissue changes associated with metal-on-metal hip replacements: reliability of anMR grading system. Skeletal radiology.Mar 2011;40(3):303-307.9 Campbell P, Ebramzadeh E, Nelson S, Takamura K,De Smet K, Amstutz HC. Histological features ofpseudotumor-like tissues from metal-on-metalhips. Clinical orthopaedics and related research.Sep 2010;468(9):2321-2327.10 Counsell A, Heasley R, Arumilli B, Paul A.A groin mass caused by metal particle debrisafter hip resurfacing. Acta orthopaedica Belgica.Dec 2008;74(6):870-874.18 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Artifact ReductionContactLeon D. RybakAssistant Professor,Vice Chair ofOperations in RadiologyNew York UniversityLangone Medical Center301 East 17thStreetNew York, NY 10003USAPhone: +1 212-598-6655Leon.Rybak@nyumc.org23 Lu W, Pauly KB, Gold GE, Pauly JM, HargreavesBA. SEMAC: Slice Encoding for Metal ArtifactCorrection in MRI. Magnetic resonance in medi-cine : official journal of the Society of MagneticResonance in Medicine / Society of MagneticResonance in Medicine. Jul 2009;62(1):66-76.24 Potter HG, Nestor BJ, Sofka CM, Ho ST, Peters LE,Salvati EA. Magnetic resonance imaging aftertotal hip arthroplasty: evaluation of periprostheticsoft tissue. The Journal of bone and joint sur-gery. American volume. Sep 2004;86-A(9):1947-1954.25 Toms AP, Marshall TJ, Cahir J, et al. MRI of earlysymptomatic metal-on-metal total hip arthro-plasty: a retrospective review of radiologicalfindings in 20 hips. Clinical radiology.Jan 2008;63(1):49-58.11 Hart AJ, Satchithananda K, Liddle AD, et al.Pseudotumors in association with well-function-ing metal-on-metal hip prostheses: a case-con-trol study using three-dimensional computedtomography and magnetic resonance imaging.The Journal of bone and joint surgery. Americanvolume. Feb 15 2012;94(4):317-325.12 Natu S, Sidaginamale RP, Gandhi J, Langton DJ,Nargol AV. Adverse reactions to metal debris:histopathological features of periprosthetic softtissue reactions seen in association with failedmetal on metal hip arthroplasties. Journal ofclinical pathology. May 2012;65(5):409-418.13 Watters TS, Cardona DM, Menon KS, Vinson EN,Bolognesi MP, Dodd LG. Aseptic lymphocyte-dominated vasculitis-associated lesion: a clinico-pathologic review of an underrecognized causeof prosthetic failure. American journal of clinicalpathology. Dec 2010;134(6):886-893.14 Donaldson JR, Miles J, Sri-Ram K, Poullis C,Muirhead-Allwood S, Skinner J. The relationshipbetween the presence of metallosis and massiveinfection in metal-on-metal hip replacements.Hip international : the journal of clinical andexperimental research on hip pathology andtherapy. Apr-Jun 2010;20(2):242-247.15 Galbraith JG, Butler JS, Browne TJ, Mulcahy D,Harty JA. Infection or metal hypersensitivity?The diagnostic challenge of failure in metal-on-metal bearings. Acta orthopaedica Belgica.Apr 2011;77(2):145-151.16 Cahir JG, Toms AP, Marshall TJ, Wimhurst J,Nolan J. CT and MRI of hip arthroplasty.Clinical radiology. Dec 2007;62(12):1163-1171;discussion 1172-1163.17 Potter HG, Foo, L.F., Nestor, B.J. What is theRole of Magnetic Resonance Imaging in theEvaluation of Total Hip Arthroplasty? HSSJ.2005;1(1):89-93.18 Potter HG, Foo LF. Magnetic resonance imagingof joint arthroplasty. The Orthopedic clinics ofNorth America. Jul 2006;37(3):361-373, vi-vii.19 Sofka CM, Potter HG. MR imaging of joint arthro-plasty. Seminars in musculoskeletal radiology.Mar 2002;6(1):79-85.20 White LM, Kim JK, Mehta M, et al. Complicationsof total hip arthroplasty: MR imaging-initial ex-perience. Radiology. Apr 2000;215(1):254-262.21 Cho ZH, Kim DJ, Kim YK. Total inhomogeneitycorrection including chemical shifts and suscep-tibility by view angle tilting. Medical physics.Jan-Feb 1988;15(1):7-11.22 Ai T, Padua A, Goerner F, et al. SEMAC-VAT andMSVAT-SPACE sequence strategies for metalartifact reduction in 1.5T magnetic resonanceimaging. Investigative radiology. May2012;47(5):267-276.Disclaimer:MR imaging of patients with metallic implants bringsspecific risks. However, certain implants are approvedby the governing regulatory bodies to be MR condition-ally safe. For such implants, the previously mentionedwarning may not be applicable. Please contact theimplant manufacturer for the specific conditional infor-mation. The conditions for MR safety are the responsi-bility of the implant manufacturer, not of Siemens.
  20. 20. MAGNETOM Flash · 1/2012 · www.siemens.com/magnetom-world 19Complete spine examinations with ease and fewer errorsProduct NewsSpine Dot Engine• Fast and standardized scanning for consistentand robust image quality with AutoAlign andAutoCoverage• Automatic detection of intervertebral discplanes and display of suggested vertebraelabellingVertebrae labelling inthe Spine Dot Engine*510(k) pending. Not for sale in the U.S. and in other countries.Experience a Dot workflow yourself and hear about other user’s favourite Dot feature at:www.siemens.com/Dot• Automatic curved reconstruction of 3D datasetsfor optimal visualization• syngo WARP* for reduction of susceptibilityartifacts, such as from MR conditional metalimplants
  21. 21. 20 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Artifact ReductionExperience with the 3 Tesla MAGNETOM Veriosystem in Spine Imaging: Benefit of 3DSequences and Reduction of Metal-RelatedArtifacts with the syngo WARP WIP-packageMarcel Wolf, M.D.1; Marc-André Weber, M.D., M.Sc.21Department of Neuroradiology, University Hospital Heidelberg, Germany2Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, GermanySpine imaging in posttraumatic and para-plegic patients has great demands onthe MRI scanner and pulse sequences. Atour institution, the Department of Diag-nostic and Interventional Radiologywithin the Department of Orthopedics,Traumatology and Spinal Cord InjuryCenter, MR imaging of the spine is para-mount in daily routine. We use the3 Tesla MAGNETOM Verio system, offer-relatively fast protocols, facilitated bythe short acquisition times.The relatively wide 70 cm open-bore ofthe 3 Tesla MAGNETOM Verio systemenables a very flexible positioning ofpatients, being crucial for those suffer-ing from hemi- or paraplegia, scoliosis,contractions and/or obesity (Fig. 1).3D sequences like syngo SPACE(Sampling Perfection with Application1 Severescoliosis.ing several advantages for patient com-fort and radiological requirements.The advantages of 3 Tesla especially fororthopedic imaging are well known:increase in signal-to-noise ratio (SNR)and less prominent effect of B1 inhomo-geneity on image quality results inclearly improved image quality and/orfaster scan times. Visualizing the wholespine in a single examination requires1A 1B 1C 1DRadiograph T2w TSE T2w TSE T1w TSE
  22. 22. MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 21Artifact Reduction Clinicaloptimized Contrasts using different flipangle Evolution) (Figs. 2 and 3) or CISS(Constructive Interference in SteadyState (Fig. 4) allow for depiction of deli-cate anatomic structures and reconstruc-tion in all directions. A high percentageof our patients underwent surgery withspinal fusion. As orthopedic hardwarecauses metal-related artifacts in MRI,adjacent structures may be difficult toevaluate. Thus special pulse sequencesthat are insensitive, or at least less sensi-tive to susceptibility changes are impor-tant in these cases. In our experience,the use of syngo WARP* WIP-packagereduced susceptibility artifacts in thepresence of orthopedic hardware (Fig. 5).In this article we report on our experi-ence in spine imaging using 3Dsequences, and demonstrated reductionof metal-related susceptibility by usingthe syngo WARP* WIP-package.3D-sequences3D-sequences like syngo SPACE (Figs. 2and 3) or CISS (Fig. 4) allow for 3-dimen-sional reconstruction with high resolu-tion in every direction and curved recon-structions. We find the later especially2 Pulsationartifacts:T2w TSE vs.T2w syngoSPACE.*510(k) pending. Not for sale in the U.S.helpful in cases of severe scoliosis tofully assess the spinal cord for cleft for-mations and tethering, because themyelon can be ‘flattened out’ as shownin the example of figure 3. The SPACE-sequence is based on, but faster thanturbo spin echo and acquires moreechoes after excitation. syngo SPACEhelps reduce SAR (Specific AbsorptionRate). Compared to turbo spin echo (TSE)the soft tissue contrast of SPACE is lesssensitive, and SPACE is more vulnerableto susceptibility artifacts.The syngo SPACE sequence is, however,less vulnerable to pulsation artifacts thana T2-weighted TSE (Fig. 2). Pulsationartifacts especially occur in the cervicalsubarachnoid space due to CSF motion.Even delicate anatomical structures likethe ventral and dorsal nerve root canbe delineated by the syngo SPACE- andCISS sequence (Figs. 2 and 4).Reduction of susceptibilityartifactsIn the presence of metallic implants, forinstance after spinal fusion surgery,adjacent structures may not be assess-able due to metal-related artifacts. Theextent of the artifacts is determined byseveral factors, such as size and compo-sition of the implant, orientation of theimplant within the main magnetic field,the strength of the magnetic field, thetype and parameters of the pulsesequence, and other imaging parame-ters like echo train length, slice thick-ness, and voxel size. The metallic com-position of the implant has a majorinfluence on the extent of the suscepti-bility artifact, with e.g. non-ferromag-netic titanium alloy producing signifi-cantly less artifacts than stainless steel.Of course, the size of the implant affectsthe extent of the artifacts, with smallimplants producing fewer artifacts thanlarge ones. The position of the patientand thus of the implant within the mainmagnetic field (B0) should be consideredas the long axis of the implant and thedirection of the main magnetic fieldshould be parallel. The choice of anadequate pulse sequence is important.Instead of gradient echo (GRE)sequences, spin echo (SE) sequencesshould be used. The 180º refocusingpulse applied in SE sequences correctsfor large magnetic field inhomogene-2A 2B 2C 2DT2w TSET2w SPACET2w TSE
  23. 23. 22 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldities. Higher magnetic field strengthsproduce larger susceptibility artifacts.But with consequently higher gradientpulses used in high-field MRI, theincreased distortion effects of highermain magnetic fields can be reduced.Field-of-view (FOV), image matrix, andsection thickness determine the voxelsize. Small voxel sizes increase the spa-tial resolution. Thus using a small FOV,a high resolution matrix, thin sections,and high gradient strengths reducesusceptibility artifacts.Case 1For an MRI examination of patients withsevere scoliosis, a flexible positioningis mandatory, facilitated by the great70 cm bore of the MAGNETOM Verioscanner. In Figure 1, radiographic (1A),T2-weighted (1B, C) and T1-weightedimages (1D) of a 51-year-old man withsevere scoliosis are shown.Case 217-year-old woman with unspecific non-radicular pain of the middle thoracicspine for 3 years. MRI did not reveal anypathologic finding. Compared to TSEsequences, syngo SPACE produces lesserpulsation artifacts in the subarachnoidspace, and allows for a more defineddelineation of delicate structures like the3 Posttraumatic syringomyelia: T2w TSE vs. T2w syngo SPACE.4 Avulsion ofnerve roots andavulsion pseudo-meningoceles:Multiplanarreconstruction ofT2w CISS.T2w TSE T2w SPACET2w CISS3A 3B 3Cventral and dorsal nerve roots. In Figure2 the pulsation artifacts in the subarach-noid space using a T2-weighted TSE (2A)and a syngo SPACE sequence (2B) arecompared. For delineation of nerve roots,a T2-weighted TSE sequence (2C) isopposed to a syngo SPACE sequence (2D).Case 351-year-old woman, who had a trau-matic fracture of the second lumbar ver-tebral body 25 years ago. Since the acci-dent, she suffered from paraplegia, butin the meantime neurologic status fur-ther deteriorated resulting in tetraplegia.4A 4B
  24. 24. MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 23Artifact Reduction Clinical5 Metal implant imaging using syngo WARP*.Marc-André Weber,M.D., M.Sc.Marcel Wolf, M.D.Image 3 shows the posttraumatic syrin-gomyelia ascending from the medullaryconus to the medulla oblongata causativefor the patient’s increasing symptoms.Contrary to T2-weighted TSE (3A), thearachnopathic adhesions (arrows) areclearly visible using a syngo SPACEsequence (3B). Another advantage of3D-sequence is the potential of multi-planar and curved reconstructions (3C).Case 424-year-old man with a posttraumaticplegia of his left arm. The MRI performed3 months after the accident demon-strates avulsion of the nerve roots C8 andT1 and consecutive avulsion pseudo-meningoceles (arrows). In Figure 4, coro-nal (4A) and transversal (4B) reconstruc-tion of the CISS sequence are shown.Case 555-year-old female suffering from pseu-doradicular pain of both legs. Thepatient underwent surgical implantationof a cage in the lumbosacral transitionand spinal fusion from the fourth lumbarto the first sacral vertebral body. As MRIis compromised in the presence ofmetallic hardware due to metal-relatedartifacts, we observed a reduction ofmetal-related susceptibility artifactswhen using the syngo WARP* WIP-pack-age. The syngo WARP* WIP-package pro-vides a set of modified sequences, whichare designed to reduce imaging artifactswhen scanning patients with metalimplants. Main source of artifacts aresusceptibility induced changes of themain magnetic field B0 near metallicobjects, leading to severe geometric dis-tortions, contrast changes, signal pile-ups, as well as signal voids. In Figure 5,the potential of the syngo WARPContactMarc-André Weber, M.D., M.Sc.Professor of RadiologyHeidelberg UniversityDiagnostic and Interventional RadiologyIm Neuenheimer Feld 11069120 HeidelbergGermanyMarcAndre.Weber@med.uni-heidelberg.deMarcel Wolf, M.D.Radiology ResidentHeidelberg UniversityDepartment of NeuroradiologyIm Neuenheimer Feld 40069120 HeidelbergGermanyMarcel.Wolf@med.uni-heidelberg.desequences (5B) in reducing metal-relatedsusceptibility artifacts is shown in com-parison to a standard TSE sequence (5A).AcknowledgementsThe excellent cooperation regardingbrain and spine imaging with Prof. Dr.Stefan Hähnel from the Department ofNeuroradiology at the University Hospi-tal Heidelberg (Head: Prof. Dr. MartinBendszus) is gratefully acknowledged.References1 Gasparotti R, Ferraresi S, Pinelli L, Crispino M,Pavia M, Bonetti M, Garozzo D, Manara O,Chiesa A. Three-dimensional MR myelographyof traumatic injuries of the brachial plexus.AJNR Am J Neuroradiol. 1997, 18(9):1733-42.2 Lee MJ, Kim S, Lee SA, Song HT, Huh YM, Kim DH,Han SH, Suh JS: Overcoming artifacts from metal-lic orthopedic implants at high-field-strength MRimaging and multi-detector CT. Radiographics2007, 27:791-803.3 Lichy MP, Wietek BM, Mugler JP 3rd, Horger W,Menzel MI, Anastasiadis A, Siegmann K,Niemeyer T, Königsrainer A, Kiefer B, Schick F,Claussen CD, Schlemmer HP. Magnetic resonanceimaging of the body trunk using a single-slab,3-dimensional, T2-weighted turbo-spin-echosequence with high sampling efficiency (SPACE)for high spatial resolution imaging: initial clinicalexperiences. Invest Radiol. 2005, 40(12):754-60.5A 5B 5CT2w CISS T2w WARP RadiographDisclaimer:MR imaging of patients with metallic implants bringsspecific risks. However, certain implants are approvedby the governing regulatory bodies to be MR condition-ally safe. For such implants, the previously mentionedwarning may not be applicable. Please contact theimplant manufacturer for the specific conditional infor-mation. The conditions for MR safety are the responsi-bility of the implant manufacturer, not of Siemens.*510(k) pending. Not for sale in the U.S. and in othercountries.
  25. 25. 24 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldProduct NewsThe term WARP summarizes methods tominimize the impact of metal implantson image quality.ChallengesMetals have highly different susceptibil-ity constants compared to tissue. Whenmetallic implants are present in the MRIexamination, the static magnetic field intheir vicinity is manipulated by stronglocal off-resonances induced by theimplants. The degree of field distortionsdepends on the shape, the locationand the material properties of the metalimplant.Distortions of the staticmagnetic field result in:■ Intra-voxel dephasing: Signal voids arevisible as black areas in the image.■ Changes in tissue contrast: Failure offat suppression and saturation bands.■ In-plane distortion: The local field off-set leads to a shift of image pixels inthe readout encoding (i.e. frequencyencoding) direction.■ Through-plane distortion: The localfield offset leads to curved and frayedslices instead of the expected flatimage plane (Fig. 1).Since both in-plane and through-planedistortions shift image pixels away fromtheir real positions, image geometryappears to be distorted. In both cases,regions with severe field changes willlead to signal voids visible as black spotsand signal pileups visible as bright spots.However, it makes sense to distinguishbetween in- and through-plane artifacts,since different techniques are needed toreduce these types of artifacts.Approaches to avoidmetal artifactsImaging in the presence of metalimplants is mostly based on (turbo) spinecho sequences due to its high immu-nity with regard to signal dephasinginduced by local off-resonances.In the following, three approaches toreduce metal artifacts are presented,that have shown promising results inclinical settings. Figure 2 depicts theireffects in-vivo compared to imagingwith standard protocols. Although othertechniques exist, they are often con-strained by excessive scan times orspecial hardware requirements.High bandwidthsequence parametersBasic acquisition parameters are adjustedto what is called high bandwidth (BW)parameters to make the MR sequenceless sensitive to field distortions.What is done:The bandwidth of both the excitationpulse and the signal readout isincreased.What it effects:A high bandwidth sequences reducesthe through-plane distortion of the sliceprofile. This implies less severe varia-tions of the apparent slice thickness, i.e.the amount of signal voids and pileups isreduced compared to standard protocolswith a low bandwidth.A high signal readout bandwidthsyngo WARP – Metal Artifact ReductionTechniques in Magnetic ResonanceImagingTheresa Bachschmidt; Ferdinand Lipps, Ph.D.; Mathias Nittka, Ph.D.Siemens Healthcare, Erlangen, GermanyImplant imaging at 3T:There is a significant differencebetween MR imaging at 3T and1.5T. In contrast to commonclinical imaging, higher fieldstrength does not necessarily implybetter image quality for patientswith metal implants. Apart fromincreased safety concerns, thelevel of image distortions scaleswith the strength of the staticfield, i.e. the level of artifacts ishigher at 3T than at 1.5T. Addition-ally, the efficiency of artifactreduction techniques is reduced bythe increased SAR constrains at 3T.1 The upper row visualizes the ideal case of sliceselection, while the lower row displays the effectson the slice selection by a distorted backgroundfield: (1A) B0 field map in slice select direction,(1B) B0 field map in direction of slice encodingwith superimposed magnetic gradient field forexcitation, and (1C) position of the excited slice.1A 1B 1C
  26. 26. MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 25Product Newsaddresses in-plane distortions: Intra-voxel signal dephasing and geometricalshift in the readout encoding directionare reduced. Consequently, the imagehas less signal voids and less pileup arti-facts related to in-plane distortions.The main drawback of high bandwidthprotocols is reduced signal-to-noise ratio(SNR) and increased specific absorptionrate (SAR). High bandwidth sequencesare very demanding in terms of scannerhardware, mainly gradient and RF powerperformance. Ultimately, the RF powerapplied by high bandwidth RF pulses islimited by the patient (SAR). Hence, theRF pulse bandwidth is more affected bythese restrictions and in-plane artifactreduction is more efficient.*510(k) pending. Not for sale in the U.S. and in othercountries.**WIP: Work in progress. SEMAC is currently underdevelopment; is not for sale in the U.S.Its future availability cannot be guaranteed.Disclaimer:MR imaging of patients with metallic implants bringsspecific risks. However, certain implants are approvedby the governing regulatory bodies to be MR condition-ally safe. For such implants, the previously mentionedwarning may not be applicable. Please contact theimplant manufacturer for the specific conditional infor-mation. The conditions for MR safety are the responsi-bility of the implant manufacturer, not of Siemens.ContactMathias Nittka, Ph.D.Siemens HealthcareMR PI ORTHPostbox 32 6091050 ErlangenGermanyPhone: +49 (9131) 84-4460mathias.nittka@siemens.comVAT* (View Angle Tilting)VAT is a modified sequence acquisitionscheme that is able to compensate forin-plane distortions. It can be easilyimplemented into a turbo spin echo(TSE) sequence.What is done:Simultaneously with the conventionalreadout gradient, an additional readoutgradient is applied along the slice selectivedirection. Its amplitude equals the oneapplied during the excitation RF pulse.What it means:The additional gradient causes shearingof the imaged pixels, as if the slice wereviewed at an angle. From a differentpoint-of-view, the VAT gradient bringsback all excited spins within the RFbandwidth and local off-resonances arecancelled exactly. Hence, the pixel shift inreadout direction is fully compensated.What it effects:In-plane distortions, more preciselythose along the readout direction, arecorrected. However, VAT may cause blur-ring of the image caused by two sepa-rate effects. One cause is the geometricslice shear, causing edges to be smearedout along the shearing direction (Fig. 3).This effect can be reduced by using thinslices and a high resolution. The secondsource of blurring is a low-pass filter3 VAT* blurring caused by the shearingof the slice: (3A) Image without VAT: thesignal of a vertical structure (vertical blueline) is well localized in a pixel (horizontalblue line); (3B) blurred image with VAT:The vertical structure appears smearedover multiple pixels.3A 3B2 Image comparison: (2A) standard protocol, (2B) high BW, (2C) VAT* and (2D) SEMAC**.2C 2Dsuperimposed on the signal readout bythe additional VAT gradient. This can bereduced by a short readout duration.SEMAC** (Slice Encoding forMetal Artifact Correction)SEMAC is based on a 2D TSE sequence.An additional encoding dimension isintroduced to enable the correction ofthrough-plane distortions.What is done:Each slice is additionally phase-encodedin the third dimension, very similar to a3D scan. This provides information onhow the slice profile is distorted, suchthat signal shifted perpendicular to theimage plane can be corrected by post-processing during image reconstruction.What it effects:Gross through-plane artifacts, whichusually cannot be handled efficientlyby high bandwidth parameters, can becorrected. In particular, imaging of largemetal structures like full knee or hipreplacements is being studied. Thismethod is very time-consuming. Despitethe use of advanced undersamplingtechniques, such as partial Fourier andparallel imaging, it is challenging toachieve scan times acceptable for rou-tine examinations.2A 2B
  27. 27. 26 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Cartilage ImagingIntroductionArticular cartilage lesions in the youngpopulation predispose to the develop-ment of precocious osteoarthritis. Poorhealing of cartilage damaged by traumaor degeneration has been ascribed toavascularity. Cartilage lesions are associ-ated with significant morbidity, includ-ing lifestyle restrictions, especially inindividuals engaged in sports. The pastdecade has seen the evolution of a num-ber of sophisticated surgical repair pro-cedures for the treatment of isolated,focal traumatic or degenerative cartilagelesions. The evolution of these surgeriesMRI Assessment of ArticularCartilage RepairDarshana Sanghvi, M.D., D.N.B.Kokilaben Dhirubhai Ambani Hospital, Mumbai, Indiahas created the need for accurate, non-invasive assessment of the repair tissue.The current generation of MR magnetsand dedicated pulse sequences allow forstructural and biochemical assessmentof the repair tissue. This information isuseful for prognostication and for com-paring the effectiveness of various typesof surgical procedures.Articular cartilage repairproceduresThe bone marrow stimulation surgeriesinclude microfracture technique, drillingand abrasion arthroplasty. The goal ofall of these procedures is to expose thepluripotential stem cells in the subchon-dral bone which then migrate to the siteof the chondral lesion. A fibrin clot isformed at the site of the microfracturesor drilling, which serves as a scaffoldfor the formation of fibro cartilaginousrepair tissue.Osteochondral autologous transfer(OATS) technique or mosaicplastyinvolves the removal of osteochondralplugs from the non-weight-bearing partof the joint, often the trochlea. Theplugs are then transferred to the chon-dral lesion along the weight-bearingpart of the articular surface. It thustransplants autologous hyaline tissue to1A 1B 1C
  28. 28. MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 27Cartilage Imaging Clinical1 An 18-year-old was involved ina motorcycle accident. (1A) Frontalknee radiograph shows flattening ofthe articular surface of the lateralfemoral condyle (arrow). (1B) Corre-sponding coronal MR STIR imageshows a traumatic osteochondrallesion of the lateral femoral condyle.(1C) The biopsy site from the non-weight-bearing part of the lateralfemoral condyle is seen in the trans-axial image. (1D and 1E) Sagittal DESSand coronal T2w images show thebiopsy site (dotted arrow) from thenon-weight-bearing lateral femoralcondyle and the site of the graft (solidarrow). There is excellent congruity ofthe osteochondral plugs with the par-ent bone. The patient remained symp-tom free at one year clinical follow up.the articular lesion. The osteochondralplugs should be perpendicular to thearticular chondral defect.Autologous chondrocyte implantation(ACI) technique involves transplantingchondrocytes harvested and replicatedfrom a non-weight-bearing part of thearticular surface into the lesion at theweight-bearing site. In the initial part ofthis two stage procedure, the chondro-cytes are harvested and cultured in vitrofor approximately five weeks. In the sec-ond part of the procedure, the harvestedchondrocytes are injected into the artic-ular chondral lesion and covered with aperiosteal flap.MRI assessmentThe aim of imaging is to examine thesuccess of surgery and assess the qualityof the repair tissue.In a successful mosaicplasty procedure,the cartilage caps of plugs should beflushed with the adjacent native carti-lage. The aim is to have the plugs placedperpendicular to the articular surface.MRI after the mosaicplasty procedureinvolves assessment of graft incorpora-tion, graft congruity and examinationof the repair tissue characteristics. Thedonor site may also be assessed. In thefirst four weeks after the procedure, theTable 1: The 8 parameters assessed by the MOCART scoring system.1 Degree of defect repair and defect filling2 Integration with border zone3 Quality of repair tissue surface4 Structure of repair tissue5 Signal characteristics of repair tissue6 Status of subchondral lamina7 Integrity of subchondral bone8 Presence of complications (adhesions and effusion)plugs and surrounding marrow havealtered marrow signal. By 12 months,the plugs and the surrounding marrowreturn to normal fatty marrow signal(Fig. 1). Persistent edema like subchon-dral bone marrow signal and cyst for-mation indicates graft failure and poorincorporation.The MOCART (MR observations of carti-lage repair tissue) system (Table 1) is anefficient scoring method for consistentreporting of the radiological features ofautologous chondrocyte implants andhas impressive interobserver reproduc-ibility. MOCART scoring may be usefulfor objective follow-up of articular carti-1D 1E
  29. 29. Clinical Cartilage Imaging2 Post ACI follow up MRI shows satisfactory fill of thelesion. The articular surface of the graft is smooth. Thesignal is similar to native cartilage. There is no defectbetween the graft and parent bone, no subchondralmarrow edema, adhesions or effusion.3 Sagittal PD-weighted images of the knee joint (3A) – unstable osteochondritisdessicans of the medial femoral condyle. (3B) Post ACI MRI shows adequate fill bythe graft (arrow).4 15-year-old girl with first episode of patellar dis-location. (4A) Axial STIR MR images show trochleardysplasia with marrow contusions at patellar apex andouter aspect of lateral femoral condyle and also a largeosteochondral defect at the patellar apex (arrow). Thecorresponding osteochondral fragment is seen in thelateral patellofemoral recess (arrow). (4B) In the firststage of surgery, arthroscopic loose body removal wasdone with cartilage biopsy. Left knee open ACI (stage 2)was done for the patellar osteochondral defect.(4C) Follow up MRI showed graft hypertrophy. Thepatient had mechanical symptoms after surgery.3A 3B24A4B 4C
  30. 30. lage repair, as it allows prospectivemulticenter studies in which results ofcartilage repair surgeries are compared[1]. An additional advantage overarthroscopy for post operative assess-ment is the ability of MRI to demonstratesubchondral marrow.The margins of the repair tissue shouldbe continuous [2] and have equivalentthickness when compared with adjacentnative cartilage and the articular surfaceshould be even (Figs. 2, 3).Adverse events after ACI include graftfailure, which is the commonest, fol-lowed by delamination, tissue hypertro-phy and local infection. Two commoncomplications of the ACI technique aregraft hypertrophy and delamination.Graft hypertrophy (Figs. 4, 5) may occur3 to 7 months after autologous chondro-cyte implantation and has been reportedas a complication in 10% to 63% of cases[3–5]. Delamination refers to separationof the graft from the parent bone.It appears as a linear fluid signal under-mining the graft. When significant, bothdelamination and graft hypertrophymay require repeat surgery, eitherdebridement in the case of hypertrophyor repeat ACI in both cases.ConclusionsArticular cartilage injury is frequent,documented in almost 63% of arthrosco-pies [6]. It is even more common in con-junction with ACL tears; about 79% ofpatients with ACL deficient knees havechondral lesions of varying severity [7].The introduction of novel cartilagerepair procedures that transplant hyalinecartilage to the injured area or have thepotential to form hyaline-like repair tis-sue, has lead to an increased require-ment for a non-invasive but accuratetechnique to assess the outcome of suchrepair surgeries. MR imaging is currentlythe optimal technique for such assess-ment [8]. The ability of MR imaging todirectly depict subchondral bone andbone marrow represents an advantageover arthroscopy MRI is also accurate forexamination of the repair tissue and itsinterface with parent cartilage and com-plications of repair surgeries such asgraft hypertrophy and delamination.MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 29Cartilage Imaging ClinicalAcknowledgement for arthroscopy images:Dr. Dinshaw Pardiwala, M.S.,Consultant Arthroscopy and Sports Medicine,Kokilaben Dhirubhai Ambani Hospital, Mumbai,India.References1 Choi YS, Potter HG, Chun TJ. MR imaging of carti-lage repair in the knee and ankle. Radiographics.2008 Jul-Aug;28(4):1043-59. Review.2 Henderson IJ, Tuy B, Connell D, Oakes B, HettwerWH. Prospective clinical study of autologouschondrocyte implantation and correlation withMRI at three and 12 months. J Bone Joint Surg Br2003; 85(7):1060–1066.3 Peterson L, Minas T, Brittberg M, Nilsson A,Sjogren-Jansson E, Lindahl A. Two- to 9-yearoutcome after autologous chondrocyte trans-plantation of the knee. Clin Orthop Relat Res2000;374: 212–234.4 Henderson I, Gui J, Lavigne P. Autologouschondrocyte implantation: natural history ofpostimplantation periosteal hypertrophy andeffects of repair-site debridement on outcome.Arthroscopy 2006;22(12):1318–1324.5 Brown WE, Potter HG, Marx RG, Wickiewicz TL,Warren RF. Magnetic resonance imaging appear-ance of cartilage repair in the knee. Clin OrthopRelat Res 2004;422:214–223.6 Curl WW, Krume J, Gordon ES, et al. Cartilageinjuries: a review of 31,576 knee arthroscopies.Arthroscopy 1997; 13:456–460.7 Noyes FR, Stabler CC. A system for gradingarticular cartilage lesions at arthroscopy.Am J Sports Med 1989; 17:505–513.8 Recht MP, Kramer J. MR imaging of the post-operative knee: a pictorial essay. Radiographics.2002 Jul-Aug;22(4):765-74. Review.5 Graft hypertrophy after ACI.ContactDarshana Sanghvi, M.D., D.N.B.Kokilaben Dhirubhai Ambani HospitalMumbaiIndiasanghvidarshana@gmail.com5Darshana Sanghvi,M.D., D.N.B.
  31. 31. 30 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Sports and Trauma ImagingPatient historyPatient is a professional basketballplayer, 13 months after left knee medialfemoral condyle microfracture, andapproximately 5 months after left kneehardware removal from prior patellarfracture. He reports no symptoms ineither knee. There is a history of pro-gressive cartilage degeneration in theright knee.Physical examinationExamination of the left knee revealsa mild joint effusion. There is goodpatellar mobility and minimal crepitusunder the patella. Range of motion isfrom full extension to 135 degrees. Neg-ative tests include Lachman, McMurray,anterior drawer, posterior drawer andpivot-shift. The knee is stable to varusand valgus stresses. He has no focalpoint tenderness. There is normal patel-lar tracking. There is mild atrophiedquadriceps on the left as compared tothe right.Imaging findingsX-rays demonstrate no changes in hisjoint space and there is no acute fractureidentified.Case Series Sports and Trauma ImagingEric K. Fitzcharles, M.D.; Charles P. Ho, Ph.D., M.D.Steadman Philippon Research Institute, Vail, CO, USA1 (1A) Initial study: Sagittal fat suppressed proton density-weighted image showing a new area of chondral thinning and fissuring withirregularity, areas to bone, delamination, and flap, with marked underlying osseous edema (arrow). (1B) 43 days later: Sagittal fat suppressedproton density-weighted image, showing a more focal sharply marginated 1.0 cm full thickness chondral defect and with areas of undermin-ing and possible flap at the inferior margin. This appears more severe than on the prior exam.1A 1BCase 1: Chondral delamination in the knee
  32. 32. MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 31Sports and Trauma Imaging ClinicalMRI initial study:(Figs. 1A, 2A and Table 1)1. Trochlea: In the central and medialaspects, there is an area of chondralthinning and fissuring with irregular-ity, areas to bone, delamination, andflap, with marked underlying osseousedema. This is new since the prioroutside examination.2. Medial femoral condyle: Slight intervalprogression of irregularity, increasedsignal, and edema in the vicinity of theposterior weightbearing surface, at themicrofracture site, now with a new1.1 cm area of delamination immedi-ately posterosuperior to the microfrac-ture site.3. Patellar chondral thinning and fissur-ing with osseous ridging, areas to bone,and edema, most likely showing intervalworsening since the prior examination.AssessmentProfessional basketball player, 13 monthsstatus post left knee arthroscopy withchondroplasty, debridement and medialfemoral condyle microfracture. He isdoing well clinically and has no symp-toms, but there is a new area of cartilagethinning and bone edema just posteriorand superior to his medial femoral con-dyle microfracture.Plan after first MRI: Since he is asymp-tomatic, the decision is made to continuephysical therapy, and start gentle agilitydrills. Repeat MRI of the left knee isplanned in 2–3 weeks to determine thestability of the findings.MRI 43 days later:(Figs. 1B, 2B, 3, and Table 1)1. Trochlea: 1.2 × 2.3 cm area of chondralthinning and fissuring with areas tobone, and underlying osseous edema,with more focal sharply marginated1.0 cm full thickness chondral defectand with areas of undermining and pos-sible flaps. This appears more severe.2. Lateral femoral condyle: New 5 mmarea of heterogenous increased signalalong the bone cartilage interface ofthe posterior weightbearing surface,possibly representing an area of soft-ening and blistering, and/or under-mining and delamination.3. Medial femoral condyle: Little or nochange involving the 1.1 cm area ofhigh signal chondral undermining anddelamination immediately posterosu-perior to the microfracture site. Thereis irregularity and increased signalinvolving the microfracture site, possi-bly with slightly more severe increasedsignal and possible slight osseouspitting along the bone-cartilage inter-face of the microfracture site.4. Patellar chondral thinning and fissur-ing with osseous ridging and areasto bone, as well as edema, slightly moresevere than on the prior examination.2A 2B2 (2A) Initial Study: Axial fat suppressed proton density-weighted image showing no chondral defect (arrow) in the lateral femoral condyle.(2B) 43 days later: Axial fat suppressed proton density-weighted image, showing a new 5 mm area of heterogenous increased signal (arrow)along the bone cartilage interface of the posterior weight-bearing surface of the lateral femoral condyle, possibly representing an area ofsoftening and blistering, and/or undermining and delamination.
  33. 33. Surgical findings after second MRI:1. Approximately 1 × 1 cm medialfemoral condyle chondral defect anddelamination posterior to the previ-ously microfractured defect. The micro-fractured area of the medial femoralcondyle previously looked to be in verygood condition.2. Left knee trochlear defect, measuringapproximately 1.5 cm × 5 mm.Chondroplasty and microfractureperformed: Unstable cartilage of themedial femoral condyle defect wasdebrided down to smooth, stable rims,with exposed subchondral bone. Similardebridement was performed about thetrochlear defect. Microfracture wasthen performed at both sites.DiscussionThis case is a good example of progres-sive chondral degeneration and delami-nation in a professional athlete, with pro-gression over time. This had a significantimpact on the performance and career tra-jectory of this athlete. Although this doc-uments the patient’s left knee, there wassimilarly progressive chondral delamina-tion disease in the right knee as well.Articular cartilage damage within jointsReferences1 Kendell SD, et al. MRI Appearance of ChondralDelamination Injuries of the Knee. AJR May2005;184(5):1486-1489.2 Hopkinson WJ, Mitchell WA, Curl WW. Chondralfractures of the knee: cause for confusion.Am J Sports Med 1985;13:309 –312.3 Levy AS, et al. Chondral delamination of theknee in soccer players. Am J Sports Med1996;24:634 –639.4 Cavalli F, et al. Interobserver Reliability amongRadiologists and Orthopaedists in Evaluation ofChondral Lesions of the Knee by MRI. Advancesin Orthopedics 2011;Article ID 743742, 4 pages.5 Tzaveas AP, Villar RN. Arthroscopic repair ofacetabular chondral delamination with fibrinadhesive. Hip Int 2010;20(1):115-119.3 Sagittal fat suppressed protondensity-weighted image showingincreased signal, underminingand possible delamination (longarrows) immediately postero-superior to the microfracture site.This is new since a prior outsideexam. There is irregularity andincreased signal involving themicrofracture site (wide arrow).may result from chronic wear or acuteinjury. Chondral delamination refers toseparation of the articular cartilage fromthe underlying cortical bone, parallel tothe joint surface, and due to shear stressat the junction of the noncalcified andcalcified cartilage. This process is oftenacute or acute-on-chronic. The overlyingcartilage layer may be intact initially, butwill often progress and develop fissuringand fragmentation, creating full thick-ness chondral defects. Untreated delam-inated chondral flaps will tend to enlargeover time.The degree of pain is often related tothe presence and severity of subchondralbone edema. There may also be locking,catching, and grinding.The prevalence and incidence of chon-dral delamination in the knee is notknown. There is an association with othertypes of chondral degeneration includ-ing defects, fissuring, and thinning [1].There is also an association with menis-cal tears [2]. In the patellofemoral com-partment, there may also be an associa-tion with patellar dislocation injuries.Plain film examination is not sensitivefor chondral delamination. MRI doesprovide visualization of articular carti-lage, and more recent high field tech-niques may be more sensitive forchondral lesions due to their higherresolution and smaller field-of-view.Although a 1996 study demonstratedpoor sensitivity with MRI [3], this hasimproved with better exam techniquesand increased radiologist knowledgeand experience. Images show linearT2-weighted signal near the intensityof joint fluid at the interface of the artic-ular cartilage and subchondral bone.One study revealed higher interobserveragreement among radiologists thanamong orthopedists in the evaluationof chondral knee lesions by MRI [4].The mainstay of treatment is surgicaldebridement, followed by cartilagerestorative procedure. The restorativeprocedure can take different forms,depending on the specifics of the indi-vidual lesion, and this is beyond thescope of discussion of this report. Tech-niques include microfracture, osteo-chondral allograft (OATS), osteochondralallograft, and autologous cartilageimplantation (ACI). A study reporting19 consecutive patients with acetabularchondral delamination showed excellentresults at one year after reattachmentwith fibrin adhesive [5], however simi-larly successful results have not beenreported in the knee. Future techniquesmay include newer generation ACI, juve-nile allograft cartilage, stem cells andscaffolds. Untreated chondral delamina-tion carries a poor prognosis [3]. Delam-inated chondral flaps will often enlargeover time due to ongoing stress at thebone-cartilage interface.32 MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-worldClinical Sports and Trauma Imaging3
  34. 34. Table 1: MRI technique.Weighting and planes Field-of-viewTR TE Sequence SlicethicknessGAP Matrix sizeT2-weighted axial 115 5320 100 Turbo Spin Echo 3.2 mm 0.3 mm 512 × 512Proton Density-weightedaxial fat suppressed150 1200 45Turbo Spin Echo fatsuppressed2 mm 0.0 mm 256 × 256Proton Density-weightedsagittal140 2570 41 Turbo Spin Echo 2 mm 0.0 mm 256 × 256Proton Density-weightedsagittal fat suppressed150 1200 45Turbo Spin Echofat suppressed2 mm 0.0 mm 256 × 256Proton Density-weightedcoronal120 2770 31 Turbo Spin Echo 3 mm 0.3 mm 640 × 640Proton Density-weightedcoronal fat suppressed160 6040 41Turbo Spin Echofat suppressed2 mm 0.3 mm 512 × 512Case 2: MelorheostosisPatient history25-year-old male with right knee pain,mainly along the medial border of hispatella and posterior. He states he hyper-extended his right knee in 2006. Hewas evaluated and was diagnosed withmelorheostosis and a possible fractureof the patella with migrating loose bod-ies and was treated conservatively. Hestates that his pain has been continuoussince then. He notes locking, catching,giving way, popping and grinding.Physical examinationFocal exam of right knee reveals no defor-mity. No lesions, erythema, ecchymosisor edema when compared to the contra-lateral limb. Flexion on his right 95 andon his left is 135 degrees. He has slighttenderness to palpation in the poplitealfossa as well as medial border of hispatella.4 Lateral ankleradiograph show-ing undulatingcortical thickeningand sclerosis(arrows) along theanterior, posterior,and epiphysealcortices of the dis-tal tibia, as wellas involving thesuperior talus.Findings are con-sistent withmelorheostosis.4MAGNETOM Flash · 2/2012 · www.siemens.com/magnetom-world 33Sports and Trauma Imaging Clinical
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