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Magnetom flash *SIEMENS*


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Magnetom flash *SIEMENS*

  1. 1. MAGNETOM Flash The Magazine of MRI Issue Number 3/2011 RSNA EditionHow I do itCerebral MRSpectroscopy at1.5T and 3TPage 6ClinicalSurgical Planningand Guidance forPediatric EpilepsyPage 18MRI of theLumbosacral PlexusPage 263T MRI of Cartilageusing 3D DESSPage 33Simultaneous MR/PET –Clinical Reality?Page 74
  2. 2. Editorial Matthias Lichy, M.D. Editor-in-Chief Dear Reader, The first time of travelling to Chicago to Sharing knowledge and showing how MR attend the annual meeting of the Radiologi- imaging technology influences patient cal Society of North America left me truly diagnosis are what MAGNETOM Flash maga- overwhelmed, not least by the huge number zine is all about. This issue is no different. of people sharing their knowledge and experience in all fields of medical imaging. Here you can read, for example, about how the Children’s Hospital in Atlanta deals There are only a few windows in the with imaging for surgical therapy planning of radiologist’s calendar in which to exchange epilepsy in children*; about imaging proto- ideas with so many colleagues from all over cols for imaging of the lumbosacral plexus at the world. For this reason, the first week Johns Hopkins Hospital; and about the clini- of December has now become a significant cal reality of simultaneous MR/PET at the week in all our calendars. University Hospital of Tübingen. Of course, these are just three of many exciting and However, even more than this, the RSNA is informative articles awaiting you on the the largest platform for learning about the following pages. They have inspired me, and latest developments in imaging technology I am sure they will inspire you. (and this applies for different imaging modalities) and how this technology influ- Enjoy reading the latest issue of Flash! ences our daily patient care. For several years now we have distributed a new issue of the MAGNETOM Flash at the RSNA (we even call it the “RSNA issue”). Matthias Lichy, M.D. *MR scanning has not been established as safe for imaging fetuses and infants under two years of age. The responsible physician must evaluate the benefit of the MRI examination in comparison to other imaging procedures.2 MAGNETOM Flash · 3/2011 ·
  3. 3. EditorialEditorial BoardWe appreciate your comments.Please contact us at Hellwich Wellesley Were Dr. Sunil Kumar S.L. Christiane BernhardtAssociate Editor MR Business Development Senior Manager Applications, Head Outbound Marketing Manager Australia and New Canada Erlangen, Germany ZealandMilind Dhamankar, M.D. Michelle Kessler Gary R. McNeal, MS (BME) Peter Kreisler, PhDSr. Director, MR Product US Installed Base Manager Advanced Application Specialist, Collaborations & Applications,Marketing, Malvern, PA, USA Malvern, PA, USA Cardiovascular MR Imaging Erlangen, Germany Hoffman Estates, IL, USAReview BoardOkan Ekinci, MD, Center of Clinical Competence – CardiologyJens-Christoph Georgi, PhD, Global Marketing Manager Biograph mMRChristian Geppert, PhD, Application Development Breast ApplicationsWilhelm Horger, Application Development OncologyJürgen Kampmeier, PhD, MR/PETBerthold Kiefer, PhD, Oncological and Interventional ApplicationsLars Lauer, PhD, Orthopedic ApplicationsHeiko Meyer, PhD, Neuro ApplicationsEdgar Müller, Cardiovascular ApplicationsSilke Quick, Global Marketing Manager Women’s HealthIgnacio Vallines, PhD, Global Marketing Manager Neurology and OrthopedicsHeike Weh, Clinical Data ManagerLisa Chuah, PhD, Collaboration Manager MR Asean MAGNETOM Flash · 3/2011 · 3
  4. 4. Content Content 6 MR Spectroscopy 18 Pediatric EpilepsyFurther clinical information Clinical Neurology 6 Case Reports: Cerebral Magnetic Visit the MAGNETOM Resonance Spectroscopy at 1.5T World Internet pages at and 3T Marc Agzarian, Angela Walls magnetom-world for further clinical 14 Case Series: Presurgical Planning information and talks with fMRI/DTI by international Jay J. Pillai, Domenico Zacà experts. 18 Neuroimaging as a Clinical Tool in Surgical Planning and Guidance for Pediatric Epilepsy Binjian Sun, et al. Clinical Orthopedic Imaging 26 High-Resolution 3T MR Neurography of the Lumbosacral Plexus Avneesh Chhabra, et al.The information presented in MAGNETOM Flash is for illustration only and is not 33 3T MR Imaging of Cartilage using 3Dintended to be relied upon by the reader for instruction as to the practice of medicine. Dual Echo Steady State (DESS)Any health care practitioner reading this information is reminded that they must usetheir own learning, training and expertise in dealing with their individual patients. Rashmi S. Thakkar, et al.This material 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 37 The Importance of MRI of the Wrist insole responsibility for the diagnosis and treatment of patients, including drugs anddoses prescribed in connection with such use. The Operating Instructions must always Patients with Rheumatoid Arthritisbe strictly followed when operating the MR System. The source for the technical data Filippo Del Grande, et the corresponding 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.4 MAGNETOM Flash · 3/2011 ·
  5. 5. Content60 74 84Multi-Station Examinations Simultaneous MR/PET Abdominal SWI How I do it Clinical Oncology 42 Configuration and Use of the MR 74 Simultaneous MR/PET – 104 Assessment of Peripheral Arterial Knee Dot Engine Clinical Reality? Disease Using High Resolution Kai Reiter, Sebastian Auer Nina Schwenzer, et al. Dynamic MR Angiography and 4D Visualization Software 50 Simplifying the Workflow of Long Edward T. Martin, Gary R. McNeal Bone Imaging for Short Bore Systems Clinical Abdominal Russell Grossen 108 Treadmill Exercise Stress CMR Imaging Orlando P. Simonetti, et al. Technology 84 Abdominal Susceptibility- Weighted Imaging: A New 56 From Local Imaging to Understanding Application for Liver Disease Business the Extent of Diseases. Clinical Yongming Dai, et al. 120 Productivity Gains in Neurological Need and Technical Advances in and Oncological Reading Multi-Region MRI 88 Dixon Sequence: Liver MRI Hannes Lücking, et al. Heinz-Peter Schlemmer, et al. and syngo.via Layouts Jean-Paul Abécassis, Denis Parienté Clinical How I do it Pediatric Imaging Clinical 124 The Networked Scanner Workflow Anja Fernandez Carmona, 60 Multi-Station Examinations in Pediatric MRI Cardiovascular Klaus Mayer Markus Lentschig Imaging 64 Pediatric Whole-Body MR Imaging 92 CMR Imaging of Profound Status Quo and Practical Aspects in Macrovascular Obstruction Daily Routine Anurag Sahu, Gary McNeal Jürgen Schäfer, et al. 100 MRI of Giant Cell (Temporal) Arteritis, GCA Thorsten A. Bley, et al. MAGNETOM Flash · 3/2011 · 5
  6. 6. Clinical NeurologyCase Reports:Cerebral Magnetic ResonanceSpectroscopy at 1.5T and 3TMarc Agzarian, BMBS (Hons), FRANZCR; Angela Walls, M.MedSc, B.App.Sc.Med Rad.Division of Medical Imaging, Flinders Medical Centre, Bedford Park, South Australia, AustraliaIntroductionThis is a pictorial review of cerebralmagnetic resonance spectroscopy (MRS) Case 1:using a 1.5T MAGNETOM Aera system Right thalamic glioblastoma multiformewith software version syngo MR D11 anda 20-channel head and neck coil and a 1A 1B3T MAGNETOM Trio system with softwareversion syngo MR B15 and a 12-channelhead matrix coil at Flinders MedicalCentre, South Australia, Australia.Magnetic resonance spectroscopy refersto the process of performing a chemicalanalysis in-vivo by the Fourier transformof the magnetic resonance signal from avoxel of tissue. Hydrogen nuclei (1H pro-tons) are used for clinical cerebral MRS.Proton spins in different molecules haveslightly different Larmor frequencies.These differences are known as thechemical shift and are expressed in parts 1A T2w TSE axial. 1B T1w SE post-gadolinium axial.per million (ppm). Chemical shifts areusually referenced to the Larmor 1C 1Dfrequency of tetramethylsilane (TMS)which is given a chemical shift of zeroppm. All in-vivo molecules of interesthave chemical shifts that increase theirLarmor frequencies relative to TMS andare thus shown on the spectrogram tothe left of zero.Cerebral MRS can be acquired using twotechniques, point resolved spectroscopysequence (PRESS) and stimulated echoacquisition mode (STEAM). PRESS hasbecome the most commonly used tech- 1C Multi-voxel PRESS MRS (TE 135 ms) 1D Multi-voxel PRESS MRS (TE 135 ms) withinnique as it has a higher signal-to-noise within the lesion in the right thalamus. normally appearing left thalamus.ratio than STEAM. Both techniques can6 MAGNETOM Flash · 3/2011 ·
  7. 7. Neurology Clinicalbe used in either single-voxel or multi- the essential requirement for MRS is The key normal resonant peaks in cere-voxel acquisitions. Single-voxel acquisi- exceptionally good magnetic field bral MRS are N-acetyl-aspartate (NAA) attions provide a better quality spectrogram homogeneity. 2 ppm, creatine (Cr) at 3 ppm and 3.9from just one region of interest at a time Cerebral MRS is usually acquired at one ppm and choline (Cho) at 3.2 ppm.whereas multi-voxel acquisitions provide or more of three different echo times, Whilst there is some regional variation ina lesser quality spectrogram from a grid short (TE 30 – 35 ms), intermediate the brain, the NAA peak is normally theof voxels acquired simultaneously. (TE 135 – 144 ms) and long (TE 270 – highest in the spectrum.Multi-voxel MRS can be performed using 288 ms). The short echo time is betterPRESS or STEAM in 2D or 3D with addi- at resolving the peaks of myoinositol, Tips for performingtional phase encoding steps. Multi-voxel glutamine, glutamate and lipids whilst cerebral MRSMRS is also known as chemical shift the long echo time tends to have less On older generation MRI scanners,imaging (CSI) or magnetic resonance baseline noise. The intermediate echo achieving high quality MRS was a diffi-spectroscopic imaging (MRSI). Regardless time is used to confirm the presence cult feat. With improved magnetic fieldof the technique and acquisition used, of lactate as the lactate peak inverts. homogeneities, higher field strengths and optimised software, performing MRS is no longer to be feared! At Flinders Med- ical Centre we routinely perform cerebral MRS using 2D multi-voxel PRESS CSI at an intermediate echo time (TE 135 ms). We have developed the following tips that have proven to work for a variety of pathologies and reduce operator depen-Patient history dance:A 61-year-old female presented with a two week history of dysarthria and left ■ Modify the volume of interest (VOI)sided weakness. Initial computed tomography (CT) scan revealed a faintly size to best suit the lesion. We oftenenhancing lesion within the right thalamus. MRI was performed to further char- use a 4 x 4 VOI to closely target aacterize the lesion. The diagnosis of glioblastoma multiforme was confirmed single lesion. Be sure to include somewith stereotactic biopsy. normal brain inside the VOI to aid in lesion diagnosis. A smaller VOI resultsSequence details in an improved shim and spectrum.Sagittal T1, axial PD, T2, T2 FLAIR, DWI, T1 and T1 post-gadolinium, coronal T2 ■ Ensure the VOI avoids structures thatand T1 post-gadolinium, 3D T1 MPRAGE post-gadolinium and multi-voxel PRESS will contaminate the baseline, such asMRS (TE 135 ms) were performed on our Siemens 1.5T MAGNETOM Aera scanner. skull, scalp, air, cerebrospinal fluid and major cerebral vessels.Imaging findings ■ Do not be afraid to perform the spec-A solitary, high T2 signal, intra-axial mass lesion is demonstrated within the troscopy in the coronal plane, particu-right thalamus with mild surrounding vasogenic oedema (Fig. 1A). Multi-focal larly nearing the vertex.contrast enhancement is present (Fig. 1B). The MRS at an intermediate echo ■ Ensure the VOI is planned accordingtime (TE 135 ms) within the lesion clearly demonstrates a significant elevation to an imaging slice. If not, performof choline at 3.2 ppm relative to NAA at 2 ppm (Fig. 1C). This is in contrast to the a T2 localizer in the best plane andnormal MRS obtained from the left thalamus (Fig. 1D). angle for the target lesion. Use ‘copy image position’ to ensure you haveDiscussion anatomical images during post-pro-Neoplasms display a characteristic MRS pattern, with an elevation of choline cessing.relative to NAA. This is the reverse of the normal situation in which NAA is the ■ Remember to use spatial saturationhighest peak in the spectrum. Choline is a component of phospholipids and bands to cover the skull, scalp andthe increase in choline seen in neoplasms has been postulated to be the result vessels. We use six saturation bandsof increased cell membrane turnover secondary to rapid cellular proliferation. positioned in 3D on all sides of the VOI.A choline: NAA ratio of greater than 2.2 is highly suggestive of a neoplasm. We found that if the saturation bands were positioned too close to the VOI we would get some baseline distor- tion. Leaving a buffer of one voxel’s MAGNETOM Flash · 3/2011 · 7
  8. 8. Clinical Neurology width between the saturation bands This can be preset in your CSI protocol. cols’. Here we have preset exactly and the VOI improves this significantly. ■ Always perform MRS at the isocentre what we wish our spectra to show,■ Ensure ‘fully excited volume’ is of the magnet. including range, scale and peak selected. This option helps to attain ■ Ensure that your patient is comfort- information. This significantly reduces homogenous excitation of all metabo- able, as their stillness is imperative. variability between operators. lites within the VOI, whilst suppressing ■ Post-processing is made easy through interference from outside the VOI. site defined defaults located in ‘proto- 2ACase 2:Right cerebellar abscessPatient historyA 62-year-old male presented with a three week history ofheadache, atxia and diplopia. Initial CT scan revealed a ringenhancing lesion within the right cerebellar hemisphere. MRIwas performed to further characterize the lesion. The diagnosisof a cerebral abscess was confirmed by the presence of pus atthe time of operation and growth of Staphylococcus aureus onculture.Sequence detailsSagittal T1 FLAIR, axial PD, T2, T2 FLAIR, DWI, T1 and T1 post-gadolinium, coronal T2 and T1 post-gadolinium, 3D T1 MPRAGEpost-gadolinium and multi-voxel PRESS MRS (TE 135 ms) wereperformed on our Siemens 3T MAGNETOM Trio scanner. 2A T2w TSE axial.Imaging findingsA solitary, ring enhancing, high T2 signal, intra-axial mass 2Blesion is demonstrated within the right cerebellar hemispherewith surrounding vasogenic oedema (Figs. 2A, B). Uniformlyrestricted diffusion is present within the lesion, being hyper-intense on DWI and hypointense on the ADC map (Figs. 2C,D). The MRS at an intermediate echo time (TE 135 ms) clearlydemonstrates an elevated lipid and lacate peak at 1.3 ppm(Fig. 2E). Importantly, there is no significant elevation ofcholine at 3.2 ppm relative to NAA at 2 ppm.DiscussionCerebral abscess characteristically demonstrates a significantlyelevated lipid and lactate peak without an elevation of cholinerelative to NAA on MRS. This allows MRS to reliably distinguishbetween cerebral abscesses and neoplasms. The uniformrestricted diffusion is also typical of cerebral abscess. Thus,the combination of MRS and DWI allows the diagnosis of acerebral abscess to be made with a high degree of certainty. 2B T1w SE post intravenous gadolinium axial.8 MAGNETOM Flash · 3/2011 ·
  9. 9. Neurology ClinicalMRS sequence detailsThe MRS sequence parameters for voxel size 10 x 10 x 15 mm, VOI 8 x 8, 4 csi_se_270), TR 1700 ms, TE 135 ms orcase 1, performed on our 1.5T averages, acquisition time 7:12 min. 270 ms, 16 x 16 matrix, FOV 160 mm,MAGNETOM Aera were: 2D multi-voxel The MRS sequence parameters for slice thickness 15 mm, voxel size 10 x 10PRESS 1H spectroscopy (csi_se_135), cases 2, 3 and 4, performed on our 3T x 15 mm, VOI 4 x 4, 3 averages, acquisi-TR 1500 ms, TE 135 ms, 16 x 16 matrix, MAGNETOM Trio were: 2D multi-voxel tion time 6:53 min.FOV 160 mm, slice thickness 15 mm, PRESS 1H spectroscopy (csi_se_135 or2C 2D2C DWI axial. 2D Corresponding ADC map.2E 2E Multi-voxel PRESS MRS (TE 135 ms) within the lesion in the right cerebellum. MAGNETOM Flash · 3/2011 · 9
  10. 10. Clinical Neurology3A 3B 3A T2w TSE axial. 3B T1w SE post intravenous gadolinium axial. Case 3: Right cerebellar glioblastoma multiforme Patient history Discussion A 69-year-old male presented three days B). No restricted diffusion is present Magnetic resonance spectroscopy can after a fall with progressively worsening within the lesion, being hypointense on be helpful in distinguishing a solitary headache. Initial CT scan revealed a ring DWI and hyperintense on the ADC map, primary cerebral neoplasm from a sol- enhancing lesion within the right cere- in keeping with T2 shine through (Figs. itary cerebral metastatic deposit. The bellar hemisphere. MRI was performed 3C, D). The MRS within the lesion, at a spectroscopic evaluation of the brain to further characterize the lesion. The long echo time (TE 270 ms) clearly dem- parenchyma outside of the lesion is diagnosis of glioblastoma multiforme onstrates a significant elevation of cho- the key in making this distinction. If, was confirmed on excision biopsy. line at 3.2 ppm relative to NAA at 2 ppm as in this case, there is an elevation of (Fig. 3E). An elevated lactate peak is also choline relative to NAA outside of the Sequence details present at 1.3 ppm. The presence of lac- lesion, it is far more likely that the Sagittal T1 FLAIR, axial PD, T2, T2 FLAIR, tate is confirmed with inversion of the lesion represents a primary cerebral DWI, T1 and T1 post-gadolinium, coronal peak when an intermediate echo time neoplasm. It is postulated that this is T2 and T1 post-gadolinium, 3D T1 (TE 135 ms) is used (Fig. 3F). Importantly, due to the infiltrative growth pattern MPRAGE post-gadolinium and multi-voxel MRS, at a long echo time (TE 270 ms) of higher grade primary cerebral neo- PRESS MRS (TE 135 ms and TE 270 ms) from white matter adjacent the lesion plasms. The lack of restricted diffusion were performed on our Siemens 3T and largely outside of the surrounding in this case is in contrast to case 2. MAGNETOM Trio scanner. vasogenic oedema, continues to demon- strate an abnormal elevation of choline Imaging findings relative to NAA (Fig. 3G). A solitary, slightly irregular, ring enhanc- ing, high T2 signal, intra-axial mass lesion is demonstrated within the right cerebellar hemisphere with mild sur- rounding vasogenic oedema (Figs. 3A,10 MAGNETOM Flash · 3/2011 ·
  11. 11. Neurology Clinical3C 3D3C DWI axial. 3D Corresponding ADC map.3E 3G 3E Multi-voxel PRESS MRS (TE 270 ms) withinthe lesion in the right cerebellum.3F 3F Multi-voxel PRESS MRS (TE 135 ms) within 3G Multi-voxel PRESS MRS (TE 270 ms) adjacent the lesion in the right cerebellum.the lesion in the right cerebellum. MAGNETOM Flash · 3/2011 · 11
  12. 12. Clinical Neurology 4ACase 4:Right frontal lobe metastasesPatient historyA 50-year-old male presented with a twoweek history of progressively worseningheadache. Initial CT scan revealed a ringenhancing lesion within the right frontallobe. MRI was performed to further char-acterize the lesion. The diagnosis of met-astatic adenocarcinoma was confirmedon excision biopsy.Sequence detailsSagittal T1 FLAIR, axial PD, T2, T2 FLAIR,DWI, T1 and T1 post-gadolinium, coronalT2 and T1 post-gadolinium, 3D T1MPRAGE post-gadolinium and multi-voxelPRESS MRS (TE 135 ms) were performedon our Siemens 3T MAGNETOM Trioscanner.Imaging findings 4A T2w TSE axial.A solitary ring enhancing, heterogeneousT2 signal, intra-axial mass lesion is demon-strated within the right frontal lobe with Discussionextensive surrounding vasogenic oedema echo time (TE 135 ms) from the white In this case, the MRS from the brain(Figs. 4A, B). The MRS within the lesion, matter adjacent the lesion, within the parenchyma outside of the lesion doesat an intermediate echo time (TE 135 ms) surrounding vasogenic oedema, does not demonstrate an elevation of cholineclearly demonstrates a significant eleva- not demonstrate an abnormal elevation relative to NAA, consistent with a soli-tion of choline at 3.2 ppm relative to NAA of choline relative to NAA (Fig. 4D). A tary metastatic deposit. This is in contrastat 2 ppm (Fig. 4C). An elevated lipid and subsequently performed CT chest to case 3.lactate peak is also present at 1.3 ppm. revealed a lobulated mass within theImportantly, MRS, at an intermediate right upper lobe (Fig. 4E).Case studies discussion References 1 Horska A, Barker PB. Imaging of brain tumors:Magnetic resonance spectroscopy is a radiation necrosis from recurrent tumor, MR spectroscopy and metabolic imaging.powerful technique that adds metabolic diagnosing metabolic and mitochondrial Neuroimag Clin N Am 2010;20:293-310. Review.information to routine MRI brain exami- disorders such as MELAS (mitochondrial 2 Al-Okaili RN, Krejza J, Wang S, Woo JH, Melhemnations. As shown in these four cases, encephalopathy lactic acidosis and ER. Advanced MR imaging techniques in the diagnosis of intraaxial brain tumors in adults.this additional information is useful in stroke like episodes) and guiding the Radiographics 2006;26:S173–S189. Review.differentiating cerebral neoplasms from biopsy of lesions. Recent improvements 3 Barker PB, Bizzi A, De Stafano N, Gullapalli RP,abscesses and distinguishing solitary in scanner hardware and software allow Lin DDM. Clinical MR spectroscopy: techniquesprimary cerebral neoplasms from MRS to be performed reliably and and applications. Cambridge University Press,solitary cerebral metastatic deposits. quickly, facilitating its incorporation into Cambridge, 2010.MRS is also beneficial in distinguishing routine clinical practice.12 MAGNETOM Flash · 3/2011 ·
  13. 13. Neurology Clinical4B 4C4B T1w SE post intravenous gadolinium axial. 4C Multi-voxel PRESS MRS (TE 135 ms) within the lesion in the right frontal lobe.4D 4E4D Multi-voxel PRESS MRS (TE 135 ms) adjacent the lesion in the right frontal lobe. 4E CT chest. Contact Marc Agzarian BMBS(Hons), FRANZCR Head of MRI4 Gillard JH, Waldman AD, Barker PB. Clinical MR 7 Weybright P, Sundgren PC, Maly P, Hassan DG, Division of Medical Imaging neuroimaging: diffusion, perfusion and spectros- Nan B, Rohrer S, Junck L. Differentiation Flinders Medical Centre copy. Cambridge University Press, Cambridge, between brain tumor recurrence and radiation Bedford Park, South Australia, 5041 2004. injury Using MR spectroscopy. AJR Australia5 McRobbie DW, Moore EA, Graves MJ, Prince MR. 2005;185:1471–1476. Phone: +61 8 8204 4405 MRI from picture to proton, 2nd edn. Cambridge 8 Burtscher IM, Skagerberg G, Geijer B, Englund E, University Press, Cambridge, 2007. Stahlberg F, Holtas S. Proton MR spectroscopy Angela Walls M.MedSc, B.App.Sc.Med Rad.6 Meyerand ME, Pipas JM, Mamourian A, Tosteson and preoperative diagnostic accuracy: an evalua- Head MRI Radiographer TD, Dunn JF. Classification of biopsy-confirmed tion of intracranial mass lesions characterized by Division of Medical Imaging brain tumors using single-voxel MR spectroscopy. stereotactic biopsy findings. AJNR Am J Neurora- Flinders Medical Centre AJNR Am J Neuroradiol 1999;20:117–123. diol 2000;21:84–93. Bedford Park, South Australia, 5041 Australia Phone: +61 8 8204 5750 MAGNETOM Flash · 3/2011 · 13
  14. 14. Clinical NeurologyCase Series: Presurgical Planningwith fMRI/DTIJay J. Pillai, M.D.; Domenico Zacà, Ph.D.Johns Hopkins University, School of Medicine, Neuroradiology Division, Russell H. Morgan Department ofRadiology and Radiological Science, Baltimore, MD, USABackgroundBlood Oxygen Level Dependent func- the location of critical gray matter and been available using only MR structuraltional Magnetic Resonance Imaging white matter areas at risk of being images. Below the fMRI imaging protocol(BOLD fMRI) is clinically indicated mainly resected during lesion removal and pro- used at our institution on a Siemens 3Tfor mapping presurgically motor, sen- vides also information on language MAGNETOM Trio scanner is reported.sory and language areas in neurosurgi- lateralization. Selected parameters of the sequencescal patients with brain tumors and other This case series aims to demonstrate of interest for this case series were aspotentially resectable lesions (e.g. how fMRI and DTI can influence the follows:epilepsy). BOLD fMRI together with Dif- surgical decision making process provid-fusion Tensor Imaging (DTI) determines ing information that would have not1 1 Multiplanar view in Neuro3D of fused T1 MPRAGE, bilateral finger1A tapping activation maps and DTI (FA-weighted) color directional maps. On the axial image two critical foci of activation are visible located pos- terior medial and lateral to the bor- der of the lesion (blue arrow). On the sagittal and coronal plane infil- tration of the corti- cal spinal tract by the tumor is well depicted.14 MAGNETOM Flash · 3/2011 ·
  15. 15. Neurology Clinical■ T1-weighted pre-, post-contrast BOLD activation maps were calculated resection was considered as a viable 3D MPRAGE based on General Linear Model (GLM) treatment option. Clinical fMRI/DTI TR/TE/TI: 2300/3.5/900 ms; FA: 9°; analysis and displayed as thresholded examination was requested primarily for voxel size: 1 x 1 x 1 mm3; t-statistic maps. DTI data were processed language and motor mapping. BW: 240 Hz/pix using the diffusion ellipsoid model and Postprocessed DTI, Fractional Anisotropy■ T2-weighted 3D FLAIR the display of the preferred diffusion (FA)-weighted color directional maps TR/TE/TI: 6000/366/2100 ms; FA: 90°; direction of the voxels was color coded and BOLD activation maps were created voxel size: 1 x 1 x 4 mm3; according to the following scheme: and fused with structural images by BW: 673 Hz/pix ■ Red: right – left using the Neuro3D Package. Imaging■ EPI BOLD 2D for functional MRI ■ Blue: superior – inferior findings show critical motor activation at TR/TE: 2000/30 ms; FA: 90°; voxel size: ■ Green: anterior – posterior the posterior margins of the lesion and 3.6 x 3.6 x 4 mm3; BW: 2232 Hz/pix The Neuro3D Package was used for mul- involvement by the tumor of the cortico-■ EPI Diffusion Tensor Imaging 2D tiplanar reconstruction and 3D visualiza- spinal tract (Fig. 1). 2 b-values (0-800), 20 directions tion. A decision in favor of surgical resection TR/TE: 6600/90 ms; FA: 90°; voxel size: of this lesion was made. The results of 2.4 x 2.4 x 3 mm3; BW: 1408 Hz/pix Case 1 brain mapping by fMRI and DTI directed This 51-year-old female patient had a a superior approach as visible on post-Material and methods diagnosis of a left frontal lobe lesion ten surgical coronal T1 contrast-enhancedAll images shown in this case series years earlier. After mild episodes of loss images (Fig. 2).were acquired at 3 Tesla (MAGNETOM of speech follow up MRI examinationTrio) using software version syngo MR showed slight increase in tumor size Case 2B17. Images were postprocessed using and demonstrated progressive contrast A 67-year-old female who presentedthe software version syngo MR B17. enhancement of this lesion, surgical with facial seizures underwent a2 2 Coronal T1 contrast- enhanced images acquired after surgery visualize the surgical approach taken by the neurosurgeon to remove the lesion in order to minimize the risk of postoperative neurological deficits. MAGNETOM Flash · 3/2011 · 15
  16. 16. Clinical Neurology 3 3 Multiplanar reconstruction of left hand activation map fused with T2 FLAIR images localizes the right primary motor cortex that was infiltrated by the mass. 4 4 Coronal reconstruction of the FA-weighted color directional maps fused with T1 MPRAGE images delineates the infiltration by the tumor of the cortical spinal tract (yellow arrow).16 MAGNETOM Flash · 3/2011 ·
  17. 17. Neurology Clinicalstructural MRI scan that revealed a 5non-enhancing T2 hyperintense rightparietal cystic lesion. The neurosurgeonrequested a functional MRI and DTI scanfor assessment of the tumor surround-ing motor function to plan possiblesurgery.GLM based activation maps from analternating hand opening/closing taskdemonstrated that the right primarymotor cortex (PMC) was quite involvedby the lesion (Fig. 3). In addition, thereconstructed coronal DTI, FA-weighted,color directional maps demonstrateinfiltration by the tumor of the fibers ofthe corticospinal tract (CST) subservingthe face and hand representation areasof the right PMC (Fig. 4). The surgical decision was to performawake craniotomy with intraoperativecortical stimulation in order to monitorconstantly the left side at risk of a tempo-rary or a permanent neurologic deficit.In the operating room the lesion removalwas stopped when the patient experi-enced weakness on the distal left lowerextremity upon stimulation. The surgicalresection was therefore subtotal asdemonstrated on the post-surgical axialT1 contrast-enhanced images (Fig. 5).ConclusionThis short case series shows how fMRI 5 Axial post-surgical T1-weighted images demonstrate the surgical trajectory takencoupled with DTI can assist neurosur- for the resection of the lesion.geons in the surgical planning of braintumor patients who are at risk of devel-oping post-operative neurological defi-cits. With increasing experience in using Referencesand interpreting functional imaging by 1 Medina, L. S., et al. Seizure disorders: Func- Contactneuroradiologists and neurosurgeons tional MR imaging for diagnostic evaluation Jay J. Pillai, M.D.and with improved standardization in and surgical treatment – prospective study. Neuroradiology Division Radiology 236, 247-53 (2005). Russell H. Morgan Department ofdata acquisition and analysis methods, 2 Petrella, J. R., et al. Preoperative Functional Radiology and Radiological SciencefMRI has the potential to become a The Johns Hopkins University School MR Imaging Localization of Language androutinely used imaging technique for Motor Areas: Effect on Therapeutic Decision of Medicine & The Johns Hopkins Hospitalneurosurgical treatment planning. Making in Patients with Potentially Resect- 600 N. Wolfe Street able Brain Tumors. Radiology 240, 793-802 Phipps B-100Acknowledgement (2006). Baltimore, MD 21287 3 Pillai, J. J. The Evolution of Clinical Functional USAThis work was funded in part by a Imaging during the Past Two Decades and Its Phone: +1 410.955.2353research grant from Siemens Medical Current Impact on Neurosurgical Planning. Fax: +1 410.614.1213Solutions, Inc. AJNR Am J Neuroradiol 31(2), 219-25 (2010). MAGNETOM Flash · 3/2011 · 17
  18. 18. Clinical Neurology Neuroimaging as a Clinical Tool in Surgical Planning and Guidance for Pediatric Epilepsy Binjian Sun, Ph.D.; Robert Flamini, M.D.; Susan Palasis, M.D.; Richard A. Jones, Ph.D. Children’s Healthcare of Atlanta, Department of Radiology, Atlanta, GA, USA Epilepsy is the fourth most common anti-epilepsy drugs on cognitive and free post-surgery rate was 45% for non- neurological disorder in all ages. Accord- psychosocial development and to lesional patients and 81% for lesional ing to the Epilepsy Foundation, 1% of increase the chances of post-operative patients. This highlights the importance the population is expected to develop neurological reorganization due to the of successfully locating, and characteriz- epilepsy before 20 years of age. Extra- inherent functional plasticity of the ing, the epileptogenic zone (EZ), which temporal cortical resection is the most pediatric brain. Tellez-Zenteno et al. sur- is defined as the volume of brain tissue common curative epilepsy surgery in veyed 3557 (697 non-lesional, 2860 responsible for the generation of sei- infants* and children, whereas temporal lesional) temporal and extra-temporal zures and whose removal consequently lobectomy is the most common in adults. epilepsy data from children for whom leads to freedom from seizures. It is Children with intractable epilepsy may structural MRI was used to define the important to characterize the structural benefit from early surgical intervention patient as being lesional or non-lesional lesion because the spatial relationship to avoid the potential negative effects of and who then underwent surgery [1]. of the lesion to the EZ varies between continued seizures and prolonged use of The meta-analysis revealed the seizure different types of lesions. For most brain1A 1A Inversion recovery and T2-weighted images acquired with high spatial resolution on a 3T MAGNETOM Trio scanner. A subtle lesion (red arrows) can be seen that is hypo- and hyper-intense on the IR and T2-weighted images respectively. 18 MAGNETOM Flash · 3/2011 ·
  19. 19. Clinical Neurology tumors, removal of the lesion, including functioning following TL resection [5]. Localization of the immediate margins of tissue around Hence thorough and meticulous pre- epileptogenic focus the lesion, will lead to freedom from surgical assessments are necessary to seizures in a high percentage of patients. address both aspects of the surgical The brain lesions associated with phar- However, in the case of focal cortical outcome, i.e., post-surgical seizure macoresistant epilepsy are often subtle dysplasia, removal of the lesion and its activity and neurological functioning. and require special expertise for their margins frequently does not lead to Neuroimaging is now routinely pre- detection and characterization. In addi- freedom from seizures, implying that the scribed for TLE patients who are poten- tion, the use of a dedicated epilepsy pro- EZ extends beyond the visible lesion in tial candidates for temporal lobectomy. tocol, rather than a standard brain pro- this case. As with any surgery there are The neuroimaging assessment includes tocol, has been shown to offer improved potential risks as well as benefits, in video EEG monitoring, structural neuro- lesion detection [6]. Dedicated TL epi- particular that the epileptogenic focus imaging (MRI), functional cerebral imag- lepsy protocols include high spatial reso- may share, or be in close proximity, to ing such as fMRI, Single Photon Emission lution thin slice, T1 and T2-weighted eloquent cortex. Thus it is not uncom- Computed Tomography (SPECT) and coronal and axial imaging with the coro- mon for patients to suffer from varying Positron Emission Tomography (PET). nal images being acquired in an oblique degrees of neurocognitive decline post- The results of these evaluations can be plane perpendicular to the long axis of surgery. For patients with temporal lobe used individually, or collectively, to: the hippocampus when evaluating TLE. epilepsy (TLE) the decline is predomi- 1) Localize and characterize the epilepto- It has also been shown that the use of a nately manifested as verbal or visual genic focus and thus help the physician 3T magnet and phased array coils further memory impairment [2–5]. For exam- to determine if surgical resection of the improves the sensitivity of lesion detec- ple, one study showed that TLE patients extratemporal cortex is appropriate. tion, when compared to 1.5T results [7]. suffered an average of 11% verbal mem- 2) Identify both the laterality of func- Figure 1 illustrates two cases where ory decline following TL resection [4]. tions such as language and the loca- epileptogenic foci were identified on Another, more recent, study revealed tion of patient-specific, functionally high resolution anatomical MR images. that although group level comparison important, cortical regions and white To date, most studies have shown that shows no significant verbal intellectual matter tracts that should, if possible, interictal diffusion imaging is not helpful loss, roughly 10% of TLE children experi- be spared by surgery. for lesion localization [8]. Changes in enced a significant decline in verbal the diffusion tensor have been detected1B 1B Inversion recovery and post-gadolinium T1 images identifying a small cystic lesion (yellow circles) in temporal lobe. MAGNETOM Flash · 3/2011 · 19
  20. 20. 2Clinical Neurologybut in general do not reach statisticalsignificance even at the group level [9].This may be, in part, due to partialvolume effects from the poor spatialresolution typically used for diffusionstudies. The development of higherresolution techniques for diffusionimaging may change this in the future.In a small portion of our epilepsy surgerypopulation, PET is used to assist the local-ization of epileptogenic focus. Due to thepoor resolution of PET images, CT and/orMRI are also performed on this group of 2 Fused PET-CT (left) and PET-MR images of a patient with tuberous sclerosis. The PET imagespatients. The PET images are then coreg- detected regions of hypometabolism in three of the multiple sub-cortical tubers (only one is shownistered with CT and MR results in order (red arrows)) allowing these to be identified as the possible seizure allow the anatomical location of areasof poor perfusion to be more accuratelyidentified. Figure 2 shows a case wherean epileptogenic lesion was identified onthe fused PET-CT and PET-MR images.Another technique that is used more fre- coregistered to and then represented as SISCOM study, the results of these studiesquently at our institution for the localiza- a color overlay on a T1-weighted volu- are used to guide the grid placement. Intion of the EZ is SISCOM (Subtraction metric MR image in order to better local- our hospital, we used the Stealth stationIctal SPECT Co-registered to MRI). This ize the lesion. One study showed that navigation system by Medtronic totechnique combines SPECT studies of a the localization of epileptic foci is 88.2% guide the electrode grid placement. Fortracer that reflects cerebral perfusion, for SISCOM but only 39.2% for side-by- the structural images, the procedure iswith the studies being acquired both side inspection of SPECT images [11]. straightforward. For the SISCOM images,ictally (during a seizure) and an interic- Figure 3 shows the SPECT data, the pro- the procedure is a little more involvedtally (between seizures) [10, 11]. Con- cessed difference image and the fused and requires the following steps:ventionally, side-by-side visual analysis of SISCOM images for a patient with TLE. 1) Register the differential SPECT imageictal and interictal SPECT images can be Using the information from SISCOM and/ to the anatomical MRI.used for lesion identification. However, or video-EEG to further refine the epi- 2) Color code the differential image.the interpretation of the images can be lepsy protocol can allow an experienced 3) Fuse the color coded SISCOM to thequite difficult due to differences in the radiologist to detect focal cortical dys- MR image on the navigation system.injected dose, tracer uptake and decay, plasia in patients who were considered After grid placement, the patients arepatient head position, and slice position- non-lesional on the standard epilepsy observed using continuous EEG videoing. To address these problems, the protocol [12]. While SISCOM can be a monitoring in order to detect seizures.SISCOM technique registers the two very useful technique, it is rather time Once a seizure is identified, the elec-SPECT scans using a mutual information and labor intensive as the injection must trodes showing the strongest activity atbased registration algorithm (we do an be performed promptly after the seizure the time of the seizure can be localized.initial crude manual registration in order for the technique to work properly. The In order to identify the spatial location ofto avoid problems with local maxima seizure must also be of sufficient dura- these electrodes a CT scan of the elec-of the registration algorithm) and then tion and of the type that typically occurs trode grid is obtained, preferably per-normalizes the two SPECT scans prior to in that patient (video EEG is required to formed immediately post-surgery incomputing a difference image that verify this). order to minimize the swelling caused byrepresents a semi-quantitative map of For patients scheduled for TL resection, post-surgical edema. Co-registering ofthe cerebral blood flow changes occur- intracranial EEG recordings are per- the CT scan to a structural MRI volume isring during the seizure [10]. Unfortu- formed in some cases in order to provide performed using the fusion tool on thenately, the poor spatial resolution and additional information of the location of MultiModality Workplace (Leonardo).contrast of the SPECT images complicate the epileptogenic focus, or to better The neurologists and radiologists canthe determination of the exact anatomi- define functional cortex that needs to be then determine the spatial location ofcal location of any seizure focus detected spared. If lesions have been identified the electrodes closest to the source ofon the differential image. For this reason, by structural MRI or an area of abnormal the seizure activity. Figure 4 illustrates athe differential image is subsequently perfusion has been identified on the case of CT grid and MRI co-registration.20 MAGNETOM Flash · 3/2011 ·
  21. 21. Clinical NeurologyIdentification of laterality and a series of language and memory related be performed under local, rather thanfunctional cortex tests during and after the Amytal effect. general, anaesthetic. The results of the test are then used to Recently, fMRI has emerged as a non-Traditionally, a neuropsychological eval- estimate the potential functional effects invasive alternative method for lateraliz-uation called the Wada test is performed of the surgery in language and memory, ing the language and motor networks,to determine which side of the brain is and help in planning the surgical and to a lesser degree – memory, inresponsible for certain vital cognitive approach. When localization of function cooperative children with epilepsyfunctions, specifically language and to a particular area of the brain is [13–15]. Brain mapping with fMRI hasmemory. The Wada test consists of a required electro-cortical stimulation also revolutionized the evaluation ofstandard neuropsychological assessment (ECS) was traditionally used. This test patients undergoing epilepsy surgery byperformed in conjunction with intraca- requires that electrodes are placed on providing a non-invasive method forrotid injections of sodium amytal. The the surface of the brain and direct identifying critical brain areas to sparedrug is injected into one hemisphere at stimulation of the electrodes on the during resection and offering a powerfula time inactivating language and/or exposed brain is then performed to map tool for studying neural plasticity. Therememory function in that hemisphere in regionally specific function. As the are numerous advantages of fMRI overorder to evaluate the contralateral patient has to interact with the surgeon other conventional modes in terms ofhemisphere. The patient is engaged in for this test the actual mapping has to language mapping: fMRI is non-invasive, does not carry the risk of either the WADA test or ECS, and different para- digms can be utilized to map different3A 3B cognitive functions. Unlike the WADA test and ECS, fMRI can be readily repeated to confirm findings, and can both lateralize and localize different aspects of language functions. Correla- tion of fMRI results with those obtained using ECS show good, but not perfect, agreement. For language paradigms, when allowing for up to 10 mm between the activated areas using the two tech- niques, the sensitivity of fMRI to detect the language areas was between 67 and 100% depending on the paradigm [16]. It should be noted that the intrinsic resolution of fMRI studies is typically in excess of 3 mm and the smoothing used3C 3D in the post-processing increases this to 5 mm or more. For the pediatric population, impaired language is the most common adverse consequence of TL surgery. At our insti- tution, language mapping is performed using one or more of three novel fMRI paradigms. The language paradigms were developed in conjunction with the Children’s National Medical Center and are designed to target both expressive and receptive language processing. They were specifically developed for the assessment of the BOLD response in the language cortex of children and 3 SISCOM result for a pediatric patient with TLE (3A). Ictal SPECT (3B). Interictal SPECT (3C). young adults under clinical conditions. Differential SPECT and (3D) SISCOM result. Specifically, the following three tasks are employed, each using a block design: MAGNETOM Flash · 3/2011 · 21
  22. 22. Clinical Neurology4 4 This case illustrates CT grid and MRI co-registration. Registration and initial visualization were achieved with 3D task card on a Siemens MultiModality Workplace (Leonardo). The electrodes can be seen as yellow/white area on the fused image due to their high intensity (i.e. high attenuation) on the CT images, areas of bone can be seen in red due to the relatively high attenuation of bone. The 3D representation was generated using in-house software which segments the CT scan to remove the bone and brain tissue and then provides an overview of the position of the grids on the surface of the brain.22 MAGNETOM Flash · 3/2011 ·
  23. 23. Clinical Neurology5 5 A case illustrating CT grid, fMRI (ADDT) activation and MRI co-registration. The CT electrodes are highlighted in green and the fMRI activations are rendered in red.a) Auditory category decision task (AU to press a single button for correct surgeons so that an optimized surgeryCAT): A category is presented followed answers or upon hearing a beep (70% plan can be developed. In some cases,by a series of words. Participants are true and 30% false for task condition, the fMRI results along with CT grid and/instructed to press a button if a word matching number of button pushes for or SISCOM results are all uploaded to thebelongs to the specified category; the corresponding control condition) navigation system and used for realtimeb) Auditory description decision task during the course of the experiment. surgery guidance. For such purposes,(ADDT): A description of an object is The responses are collected and inspec- the fMRI data is processed with FSLpresented to the participants. The par- ted for the purposes of task monitoring ( and the statis-ticipants are required to press a button and evaluation of response accuracy. tical parametric maps are exported inwhen the description is consistent with The paradigms are also graded for skill DICOM format, which is required by ourthe matched object; and the appropriate version is selected navigation system. Briefly, the fMRI datac) Listening to stories (Listening): Stories for each participant based on his/her is pre-processed using the standardbased on Gray Oral Reading Test are neuropsychological test score. All MRI options and then analyzed using a gen-presented with pseudorandom inserted scans are conducted on a Siemens 3T eral linear model, the resulting spatialbeeping sounds. Participants are instruc- MAGNETOM Trio scanner equipped with statistical maps are then projected backted to press a button when a beep is 8-channel receive only head coil. A gra- to the corresponding anatomical MRIsheard while listening to the story. The dient echo EPI with TR = 3 sec and TE = and fed to the navigation software.participants are told that they will be 36 milliseconds and a nominal spatial Figure 5 shows a case where we simulta-questioned on the story after the scan in resolution of 3.0 mm3 is used for the neously overlaid a CT grid scan (seg-order to try and ensure that the partici- fMRI studies. Oblique axial slicing is cho- mented to exclude brain tissue andpant pays attention to the story. sen for the fMRI acquisitions in order to bones) and the ADDT fMRI result on theThe rest condition for all three paradigms increase coverage and reduce suscepti- anatomical MRI image. Diffusion tensorconsists of reverse speech of the experi- bility effects. Inline fMRI analysis is done imaging (DTI) can also be used to mapmental condition with intermittent within the BOLD task card. Pediatric neu- the major white matter pathways whichbeeps as cues for button presses. All par- roradiologists and neuropsychologists project into the temporal lobe and thisadigms comprise five 30 second task use these results to determine the later- information can be used by the surgeonsblocks and five 30 second control (rest) ality of language and to locate the corti- to try and spare these regions and henceblocks, resulting in a total duration of cal regions implicated in language. The preserve the communication with otherfive minutes. Participants are instructed results are communicated to the neuro- regions of the brain. To achieve this goal, MAGNETOM Flash · 3/2011 · 23
  24. 24. Clinical Neurologywhite matter tracts connecting vital cor- Referencestical regions (as identified by fMRI) are 1 Tellez-Zenteno, J.F., et al., Surgical outcomes in 11 O’Brien, T.J., et al., Subtraction ictal SPECT lesional and non-lesional epilepsy: a systematic co-registered to MRI improves clinical usefulnesstraced on DTI images, and those tracts review and meta-analysis. Epilepsy Res, 2010. of SPECT in localizing the surgical seizure focus.are then uploaded onto the navigation 89(2–3): p. 310-8. Neurology, 1998. 50(2): p. 445-54.system for surgical guidance. The DTI 2 Binder, J.R., et al., A comparison of two fMRI 12 Ruggieri, P.M., et al., Neuroimaging of the corti-data is acquired axially using a 30 direc- methods for predicting verbal memory decline cal dysplasias. Neurology, 2004. 62(6 Suppl 3):tions EPI sequence (b = 1000 sec/mm2), after left temporal lobectomy: language p. S27-9. lateralization versus hippocampal activation 13 Binder, J.R., et al., Determination of language5 b = 0 scans, TR/TE = 8900/96 ms, asymmetry. Epilepsia, 2010. 51(4): p. 618-26. dominance using functional MRI: a comparisona parallel imaging factor of 2 and a 3 Helmstaedter, C. and C.E. Elger, Cognitive con- with the Wada test. Neurology, 1996. 46(4):nominal spatial resolution of 2 mm3. sequences of two-thirds anterior temporal p. 978-84.Our radiologists first review the DTI lobectomy on verbal memory in 144 patients: 14 Gaillard, W.D., C.B. Grandin, and B. Xu, Develop- a three-month follow-up study. Epilepsia, 1996. mental aspects of pediatric fMRI: considerationsresults produced by Neuro3D on the 37(2): p. 171-80. for image acquisition, analysis, and interpreta-Siemens console and determine if DTI 4 Ojemann, G.A. and C.B. Dodrill, Verbal memory tion. Neuroimage, 2001. 13(2): p. 239-49.guidance is appropriate. If so whole deficits after left temporal lobectomy for 15 Saykin, A.J., et al., Language before and afterbrain tractography using the FACT algo- epilepsy. Mechanism and intraoperative predic- temporal lobectomy: specificity of acute changesrithm is performed. The relevant fiber tion. J. Neurosurg, 1985. 62(1): p. 101-7. and relation to early risk factors. Epilepsia, 5 Westerveld, M., et al., Temporal lobectomy in 1995. 36(11): p. 1071-7.tracts are generated using the fMRI children: cognitive outcome. J Neurosurg, 16 FitzGerald, D.B., et al., Location of language inresults as seed/target points. Binary 2000. 92(1): p. 24-30. the cortex: a comparison between functionalmasks are then created from the fiber 6 Von Oertzen, J., et al., Standard magnetic MR imaging and electrocortical stimulation.tracts (voxels in the path of the tracts resonance imaging is inadequate for patients AJNR Am J Neuroradiol, 1997. 18(8): p. 1529-39.are assigned value 1 while others are with refractory focal epilepsy. J Neurol Neurosurg Psychiatry, 2002. 73(6): p. 643-7.assigned value 0). The resulting binary 7 Knake, S., et al., 3T phased array MRI improvesimages are exported as DICOM images the presurgical evaluation in focal epilepsies:and sent to the navigation system (in a prospective study. Neurology, 2005. 65(7): Contacta similar manner to the SISCOM and p. 1026-31. Richard A. Jones 8 Wehner, T., et al., The value of interictal Department of RadiologyfMRI results) where they can be used to diffusion-weighted imaging in lateralizing Children’s Healthcare of Atlantahighlight the fiber tracts to be avoided temporal lobe epilepsy. Neurology, 1001 Johnson Ferry Roadduring surgery. 2007. 68(2): p. 122-7. Atlanta, GA 30342These imaging techniques are now a 9 Widjaja, E., et al., Subcortical alterations in tissue USAroutine part of the clinical workup for all microstructure adjacent to focal cortical dyspla- sia: detection at diffusion-tensor MR imaging byof the epilepsy patients at our institution. using magnetoencephalographic dipole clusterThey have greatly improved our ability localization. Radiology, 2009. 251(1): p. detect focal lesions, to minimize the 10 Nehlig, A., et al., Ictal and interictal perfusion *MR scanning has not been established as safe for imaging fetuses and infants under two years ofdetrimental effects of epilepsy surgery variations measured by SISCOM analysis in age. The responsible physician must evaluate theand to provide improved guidance to the typical childhood absence seizures. Epileptic benefit of the MRI examination in comparison to Disord, 2004. 6(4): p. 247-53.neurosurgeon. other imaging procedures.24 MAGNETOM Flash · 3/2011 ·
  25. 25. How-I-do-itTry them on your systemTrial licenses for most of the 1applications featured in this issue ofMAGNETOM Flash are available freeof charge for a period of 90 days:Please contact your local Siemens rep-resentative for system requirementsand ordering details or visit us online*at further details, product overviews,image galleries, step-by-step videos,case studies and general requirementinformation. 1 Multi-voxel MR Spectroscopy, page 6. 2 32 Functional MR imaging (syngo BOLD) and Diffusion Tensor Imaging 3 Networked Scanner: Simultaneously work with MAGNETOM Skyra/Aera (syngo DTI), page 14. and syngo.via on two screens, page 124. 44 Susceptibility-weighted imaging (syngo SWI), page 84. *Direct link for US customers: MAGNETOM UK · 2/2011 · 25 Direct link forFlashcustomers:
  26. 26. Clinical Orthopedic ImagingHigh-Resolution 3T MR Neurographyof the Lumbosacral PlexusAvneesh Chhabra, M.D.; Aaron Flammang, MBA, BS; John A. Carrino, M.D., M.P.H.Russell H. Morgan Department of Radiology and Radiological Science,Johns Hopkins Medical Institutions, Baltimore, MD, USA1A 1B 1C 1A–C Lumbosacral Plexus 3T MR Neurography evaluation: Isotropic multiplanar reformats from 3D T2 SPACE (1A–1C).AbstractThe lumbosacral (LS) plexus is a series of trum of pathologies along with their ings and electrodiagnostic study results.nerve convergences and ramifications respective imaging findings using However, differentiation of LS plexopathythat provide motor and sensor innerva- 3 Tesla MR Neurography. from spine related abnormality andtion to pelvis and lower extremities. LS definition to type, location and extentplexopathy is a serious condition caused Introduction of pathology often remains a diagnosticby a variety of pathologies. Magnetic The lumbosacral (LS) plexus is com- challenge due to deep location of theResonance Neurography is an important prised of an intricate architecture of nerves and variable regional musclemodality for evaluation of LS plexopathy nerves that supply the pelvis and lower innervation [1, 2]. With current highdue to variable clinical presentations extremity. It can be subject to a variety resolution 3 Tesla (T) Magnetic Reso-and deep location leading to suboptimal of pathologies, which may result in LS nance Neurography (MRN) techniques,accessibility of the plexus to electrodiag- plexopathy, a clinical syndrome that diagnostic evaluation of large LS plexusnostic studies. This article describes the includes motor and sensory distur- branches, such as sciatic and femoralrole of MR Neurography in evaluation of bances. The diagnosis of LS plexopathy nerves, as well as smaller segments,the LS plexus and illustrates the spec- has traditionally relied on clinical find- such as nerve roots convergences and26 MAGNETOM Flash · 3/2011 ·
  27. 27. Orthopedic Imaging Clinical1D 1E1F 1G 1D–G Coronal reconstructed 3D STIR SPACE (1D) showing sciatic nerves (arrows). Axial T1w (1E) and T2 SPAIR (1F) images showing bilateral femoral nerves (arrows) and lateral femoral cutaneous nerves (arrowheads). MIP coronal 3D STIR SPACE (1G) image showing bilateral LS plexus nerve roots, femoral nerves (arrowheads) and sciatic nerves (arrows). peripheral nerves is feasible, aiding in ventral rami of lumbar (L1–4 +/– T12), and lateral femoral cutaneous nerves pre-surgical evaluation and appropriate sacral (S1–4 and LS trunk, L4–S1) and (L2, 3)]. All branches exit lateral to the patient management [3, 4]. This article the lower sacrococcygeal (S2–4 and C1) psoas muscle and course under the provides a pertinent discussion of the nerves, respectively [5]. The plexus is inguinal ligament, except the obturator LS plexus anatomy, current role of MRN formed lateral to the intervertebral nerve and LS trunk, which exit medial to in evaluation of plexopathy and foramina and various branches course the psoas muscle. The sacral plexus gives describes the respective imaging find- through the psoas major muscle. The rise to anterior branches, namely the ings of various pathologies using 3T MR ventral rami are further split into ante- tibial part of the sciatic nerve (L4–S3), Neurography. rior and posterior divisions. The anterior pudendal nerve (S1–4) and medial part divisions give rise to the iliohypogastric of the posterior femoral cutaneous Anatomic considerations (L1), ilioinguinal (L1), genitofemoral nerve (S1–3) and, posterior branches, The LS plexus is comprised of lumbar (L1-L2) and obturator nerves (L2–4). namely the common peroneal part of the plexus, sacral plexus and the pudendal The posterior divisions combine to form sciatic nerve (L4–S2), superior (L4–S1) plexus, with contributions from the the posterior branches [femoral (L2–4) and inferior gluteal nerves (L5–S2), MAGNETOM Flash · 3/2011 · 27
  28. 28. Clinical Orthopedic Imaging Table 1: S The 3T MR imaging protocol employed in our institution of the evaluation of the lumbosacral plexus. Sequence Slice Field-of-view Voxel size (mm3) TR/ TE (ms) Turbo factor (cm) Axial T1 TSE BL 33 0.64 800/12 6 Axial T2 SPAIR BL 33 1.00 4500/80 17 Coronal PD SPAIR BL 36-38 0.6 4980/38 7 Coronal T1 TSE BL 36-38 0.5 550/10 3 3D Coronal STIR SPACE BL 36-38 1.45 1500/103 61 Lumbar 3D Sagittal T2 SPACE 28 1.45 1000/99 69 spine Coronal 3D VIBE * BL 36-38 0.58 4.39/2.01 –Abbreviations are: TSE = Turbo Spin Echo, SPAIR = spectral adiabatic inversion recovery, STIR = short tau inversion recovery, 3D SPACE = three-dimen-sional Sampling Perfection with Application optimized Contrasts using constantly varying flip angle Evolutions, VIBE = Volume Interpolated Breath-hold Exam (* optional), BL = bilaterallateral part of the posterior femoral clinical and laboratory findings. MRN guidance during perineural and intra-cutaneous nerve (S1–3) and the nerve may be used in the latter case to confirm muscular medication the piriformis muscle (L5, S2). The lumbar plexitis / plexopathy in clinicallyabove two plexuses connect via the LS confusing presentation and underlying Clinical findingstrunk to form the LS plexus [2, 5]. known systemic condition. In addition, a LS plexopathy most often presents with primary or idiopathic form of LS plexop- asymmetric weakness, pain and/or par-Pathologic conditions and athy may occur, possibly due to altered esthesias in the lower extremities involv-indications of MRN immunological response and is consid- ing multiple contiguous LS nerve rootThe LS plexus is relatively protected by ered analogous to idiopathic brachial distributions. Generally, unilateral local-the axial skeleton and entrapment neu- plexopathy [6–8]. The entity has a favor- ization of symptoms indicates a localropathy is much less common than bra- able outcome and spontaneous recov- pathology, whereas bilateral symptomschial plexopathy. It is considered as the ery, whereas its diagnosis is based upon suggest a systemic process. The clinicalcounterpart of the brachial plexus in the exclusion of other etiologies and some- picture often varies depending upon thelower body and is affected by similar times may require confirmation with location and degree of plexus involve-types of diseases. The LS plexus may be MRN in case of indeterminate electrodi- ment. In cases of involvement of theinvolved by local processes in the viscin- agnostic results. An important indication upper nerve roots, patients predomi-ity of the plexus, such as extrinsic com- of MRN is in patients under consider- nantly present with femoral and obtura-pression by space occupying lesions, ation for surgery for peripheral nerve tor nerve symptoms. LS trunk and upperinjury or infiltration by tumor / infec- lesions (piriformis syndrome/meralgia sacral plexus lesions result in foot droptious process – which is an indication for paresthetica), post abdominal surgery depending on the extent of involvementMRN; or in systemic conditions, such entrapment of ilioinguinal/genitofemo- and weakness of knee flexion or hipas metabolic, autoimmune, vasculitis, ral nerves, or after injury to a large abduction. Sensory symptoms may varyischemic or inflammatory disorders – branch (sciatic, femoral, obturator). based on the individual nerves involved,which are usually diagnosed based on Finally, MRN is increasingly used for which may include numbness or28 MAGNETOM Flash · 3/2011 ·
  29. 29. Orthopedic Imaging Clinical2A 2B 2B 2 Normal vs abnormal LS Plexus. Coronal MIP 3D STIR SPACE images in a nor- mal subject (2A) and another sub- ject with schwan- nomatosis (arrows in 2B).3A 3B 3 Piriformis syndrome – large LS plexus branch nerve abnormality. 33-year-old man with right buttock and pelvic pain, suspected piriformis syndrome. Coronal T1w (3A) and coronal MIP 3D STIR SPACE (3B) images through the pelvis show split right sciatic nerve by an accessory slip of the right piriformis muscle (arrow). Notice abnormal T2 hyperintensity of the sciatic nerve in keeping with entrapment neuropathy.dysesthesia in the anterolateral thigh MRN technique and normal tures under interrogation, it is essentialfrom lateral femoral cutaneous nerve appearances to use high resolution imaging with ainvolvement; in the mons and labia Compared to 1.5T systems 3 Tesla combination of 2D (dimensional) and 3Dmajora from genitofemoral nerve (MAGNETOM Verio and MAGNETOM Trio, isotropic spin echo type imaging forinvolvement and in the lower abdomen Siemens, Erlangen, Germany) imaging optimal assessment. In the presence ofand inguinal area, upper medial thigh or is preferred for most MRN examinations known metal* in the area of imaging,pelvis from damage to the ilioinguinal, by the authors due to high quality scans 1.5T imaging is preferred. Table 1 andiliohypogastric, or pudendal nerves, obtained by these systems due to better Fig. 1 show the 3T MRN imaging protocolrespectively. Rarely, there may be associ- signal-to-noise ratio and contrast reso- employed at Johns Hopkins for the eval-ated bowel and bladder incontinence as lution available in short imaging times. uation of the LS plexus. For fascicularwell as sexual dysfunction [6–8]. Due to the relatively small nerve struc- architecture and subtle signal intensity MAGNETOM Flash · 3/2011 · 29