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Vp texas by yuan

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Vp texas by yuan

  1. 1. MR Imaging of Atherosclerosis:MR Imaging of Atherosclerosis: The Seattle ExperienceThe Seattle Experience University of Washington Chun Yuan, Ph.D. Thomas S. Hatsukami, M.D.
  2. 2. Human Carotid Plaque The First High Resolution Carotid 1.5 T MRI by Yuan et al June 1998
  3. 3. The First High Resolution CarotidThe First High Resolution Carotid ImagingImaging by a 3T MRIby a 3T MRI Fine structures like plaque cap now can be imaged. May 2003
  4. 4. 1.5 T; 2 NEX; resolution 0.63x0.63 mm 3 T; 2 NEX; resolution 0.63x0.63 mm 3 T; 1 NEX; resolution 0.27x0.55 mm1.5 T; 1 NEX; resolution 0.27x0.55 mm Comparing 1.5 and 3TComparing 1.5 and 3T without Software Enhancementwithout Software Enhancement GE 3T and 1.5T Scanners with Identical Phased-array Design
  5. 5. Carotid ArteryCarotid Artery AtherosclerosisAtherosclerosis • Stroke/TIA • Location • Carotid endarterectomy (CEA) • Access to plaque specimen • In vivo and Ex vivo studies • Histology
  6. 6. Carotid MRICarotid MRI HardwareHardware Phased array coilsPhased array coils • Designed / built in-house • Flexible • Bi-lateral • Significant SNR improvement Head holderHead holder • Restricts motion • Consistent positioning • Patient comfort - Hayes, et al., JMRI 6:109-112, 1996. Pathway Medical Technologies, Redmond, WA
  7. 7. Imaging Protocol:Imaging Protocol: Multi-Contrast WeightingMulti-Contrast Weighting • DIR/MDIR technique • Bright/black blood • Spatial resolution • 0.31 x 0.31 x 2 mm • Total scan time • 30 minutes • Serial scan capability TOF T1W PDW T2W
  8. 8. Quantitative AnalysisQuantitative Analysis • Quantitative Vascular Analysis System (QVAS) PD T1 TOF Fibrous cap Lipid core Calcium Media/adventitia Lumen Hemorrhage Kerwin WS, et al. Proceedings of MICCAI 4th International Conference, 786-794, 2001.
  9. 9. QVAS: MorphologicalQVAS: Morphological IndexesIndexes • Vessel lumen and wall area/volume • Wall thickness • Eccentricity and lesion distribution n C, et al. IEEE Transactions on Image Processing, 10(6): 865-873, 2001.
  10. 10. Inter-scan and Inter-raterInter-scan and Inter-rater VariabilityVariability V1 V2
  11. 11. Blood Vessel Volume MeasurementBlood Vessel Volume Measurement • Precision of MRI for Measuring Plaque Volume • 3.8 – 4.6% for T1W, PDW, & T2W imaging • Possible to detect a > 13% change in plaque volume with 95% confidence • IQ – most important factor
  12. 12. Hemorrhage - Recent (Type VI) TOF T1WI PDWI T2WI Mallory’s Trichrome MRI Based Lesion TypeMRI Based Lesion Type
  13. 13. MRI Based Lesion TypeMRI Based Lesion Type TOF T1WI PDWI T2WI H&E Type VIII: Fibrous Lesion
  14. 14. Fibrous Cap CharacteristicsFibrous Cap Characteristics Gross Specimen Masson’s Trichrome In Vivo 3D-MOTSA Image 1 32 3 1 = Fibrous Cap Rupture 2 = Intraplaque Hemorrhage 3 = Thick Fibrous Cap Thick fibrous cap appears as dark band between lumen and plaque core. Recent plaque hemorrhage appears hyperintense.
  15. 15. Risk of Symptoms by Cap Status onRisk of Symptoms by Cap Status on MRIMRI 95% CI 3, 210 1, 104 --- 23 10 1 OR for Sx 70% 50% 9% % w/ Sx Ruptured Cap Thin Cap Thick Cap Cap Status p = 0.001 Mann-Whitney test for cap status vs. symptoms
  16. 16. DCE-MRI ProtocolDCE-MRI Protocol • MRI: 2DSPGR (TR / TE = 100 / 3.5 msec) • Contrast agent: 20 ml Omniscan (Gadolinium-based) administered at 2ml/sec time ~15 sec Dynamic MRI Contrast injection Pre-contrast MRI Post-contrast MRI t = 1 t = nt = 3t = 2 ...
  17. 17. DCE- Kinetic Model ResultsDCE- Kinetic Model Results 0 5 10 15 20 25 30 0 0.5 1 1.5 2 2.5 3 fVA (%) by histology fBV(%)byMRI R = 0.80 p < 0.001
  18. 18. SummarySummary • High resolution MRI • Carotid phased array • Black/bright blood • Multi-contrast weighting • Contrast agent application • High resolution MRI • Fibrous cap • Microvessels • Lipid core • Ca • Lumen surface condition • Matrix • Volume
  19. 19. Grant support provided by: NIH and AstraZeneca Pharmaceuticals, Pfizer, and Esperion Therapeutics vil.rad.washington.edu Department of Radiology Niranjan Balu Tobias Saam Baocheng Chu Dongxiang Xu William S. Kerwin Annette Kampshulte Zachary E. Miller Vasily Yarnykh Department of Pathology Russell Ross Steve Schwartz Randy Small Marina S. Ferguson Department of E. E. Jenq Neng Hwang Ying Luo Mountain Whisper Light Nayak Polissar C. Yuan, T.S. Hatsukami

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