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MR Imaging for the Evaluation of
Carotid Atherosclerosis
David Saloner, PhD
Professor of Radiology
VA Medical Center
Unive...
What is the risk factor associated
with carotid disease?
a b c d
Identical diameter stenosis but different geometries
and/...
Standard of truth - excised specimen
High Resolution MRI of Resected Plaque
• Provides perspective on wealth of
information available from MR imaging of
geomet...
Longitudinal MRI
Transverse MRI
Carotid specimen
0
10
20
30
40
50
60
circular crescentic elliptic lobular
frequency
Cross-section through
maximal stenosis for
9 specimens
...
Fibrous cap over necrotic core
Histology MRI
MRI shows good contrast between fibrous cap and
necrotic core as confirmed on...
High Resolution MRI In Vivo
• Can we obtain comparable data in vivo that will
provide measures of 3d descriptors?
Will the...
High resolution
TOF-MRA using
high sensitivity
phase-array carotid
coil
0.7mm x 0.7mm x1.0mm
Tacq = 6min
time
carotid jugular
Inject 30cc
Ttr
Td
Acquisition time
Intravenous injection
of GdDTPA -
contrast enhanced
MRA (CE-MRA)
...
CE-MRA 3D TOF
CE-MRA (25 s) has
little motion blurring
compared to 3D
TOF (10 min)
CE-MRA 3D TOF
CE-MRA
(TE=1.5 ms)
has reduced
sensitivity to
complex flow cf
3D TOF
(TE=6.5ms)
CE-MRA
3D TOF
Caveat: CE-MRA not always better.
Tight stenosis seen as flow void on
CE-MRA
Dedicated
equipment provides
improvements -
phased-array carotid
coil gives increased
SNR hence better
resolution
Conventi...
High-resolution 3D imaging of lumenal contours
High resoln. MRA of lumenal contours in vivo
• Provides good delineation of vascular contours
with reasonable resolution -...
Native image
with coil
Adjusted image
Phased-array coils with postprocessing
Calcification
Calcification also noted on MRI
High resoln. MRI of vessel wall in vivo
• Provides good delineation of plaque components
with reasonable resolution - abou...
Dr. David Saloner, VASF, and Dr. F. Scott Pereles, Northwestern
High Resolution
Carotid Imaging
3D CE-MRA 3D TrueFISP 2D T...
Future of MRA/I
• Improved hardware and software
• Use of 3D black blood studies, plaque enhancement
following contrast in...
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Saloner presentation

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Saloner presentation

  1. 1. MR Imaging for the Evaluation of Carotid Atherosclerosis David Saloner, PhD Professor of Radiology VA Medical Center University of California San Francisco
  2. 2. What is the risk factor associated with carotid disease? a b c d Identical diameter stenosis but different geometries and/or composition
  3. 3. Standard of truth - excised specimen
  4. 4. High Resolution MRI of Resected Plaque • Provides perspective on wealth of information available from MR imaging of geometry and composition • (200µm)3 resolution (not currently obtainable in vivo)
  5. 5. Longitudinal MRI Transverse MRI Carotid specimen
  6. 6. 0 10 20 30 40 50 60 circular crescentic elliptic lobular frequency Cross-section through maximal stenosis for 9 specimens Stenosis shape
  7. 7. Fibrous cap over necrotic core Histology MRI MRI shows good contrast between fibrous cap and necrotic core as confirmed on histology
  8. 8. High Resolution MRI In Vivo • Can we obtain comparable data in vivo that will provide measures of 3d descriptors? Will these permit us to follow the progression of geometry (X-sectional area, plaque bulk), and compositional features (lipidic core, fibrous cap)? • Can we identify the features of the plaque that correlate with rapid progression in a prospective fashion? • Can we identify the features of the plaque that confer neurological risk?
  9. 9. High resolution TOF-MRA using high sensitivity phase-array carotid coil 0.7mm x 0.7mm x1.0mm Tacq = 6min
  10. 10. time carotid jugular Inject 30cc Ttr Td Acquisition time Intravenous injection of GdDTPA - contrast enhanced MRA (CE-MRA) -can be used to address some shortcomings of conventional MRA.
  11. 11. CE-MRA 3D TOF CE-MRA (25 s) has little motion blurring compared to 3D TOF (10 min)
  12. 12. CE-MRA 3D TOF CE-MRA (TE=1.5 ms) has reduced sensitivity to complex flow cf 3D TOF (TE=6.5ms)
  13. 13. CE-MRA 3D TOF Caveat: CE-MRA not always better. Tight stenosis seen as flow void on CE-MRA
  14. 14. Dedicated equipment provides improvements - phased-array carotid coil gives increased SNR hence better resolution Conventional coil Phased-array coil
  15. 15. High-resolution 3D imaging of lumenal contours
  16. 16. High resoln. MRA of lumenal contours in vivo • Provides good delineation of vascular contours with reasonable resolution - about 0.5 mm3 voxel • 3D depiction of contours • Little or no invasiveness • Provides potential to evaluate cross-sectional area, and surface irregularities
  17. 17. Native image with coil Adjusted image Phased-array coils with postprocessing
  18. 18. Calcification Calcification also noted on MRI
  19. 19. High resoln. MRI of vessel wall in vivo • Provides good delineation of plaque components with reasonable resolution - about 0.5 mm3 voxel • Sequential 2D slices providing 3D overview • Non invasive • Provides potential to evaluate plaque inhomogeneity - perhaps lipid core, fibrous cap, calcification, intraplaque hemorrhage
  20. 20. Dr. David Saloner, VASF, and Dr. F. Scott Pereles, Northwestern High Resolution Carotid Imaging 3D CE-MRA 3D TrueFISP 2D T2-TSE New rapid methods - new hardware
  21. 21. Future of MRA/I • Improved hardware and software • Use of 3D black blood studies, plaque enhancement following contrast injection • Implementation in longitudinal studies of disease progression/regression • Establish true determinants of neurological risk

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