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Topics in Magnetic Resonance Angiography Research and Some Potential New Directions

Topics in Magnetic Resonance Angiography Research and Some Potential New Directions. Dennis L. Parker et al. Goal – Increase Vessel Signal. Acquisition Techniques RF coils, Pulse sequences, Field strength Post Processing Vessel enhancement, noise reduction techniques Vessel Segmentation

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Topics in Magnetic Resonance Angiography Research and Some Potential New Directions

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  1. Topics in Magnetic Resonance Angiography Researchand Some Potential New Directions Dennis L. Parker et al.

  2. Goal – Increase Vessel Signal • Acquisition Techniques • RF coils, Pulse sequences, Field strength • Post Processing • Vessel enhancement, noise reduction techniques • Vessel Segmentation • Aneurysm Screening • New contrast agents

  3. Outline • Acquisition Techniques • RF coils, Pulse sequences, Field strength • Post Processing • Vessel enhancement, noise reduction techniques • Vessel Segmentation • Aneurysm Screening • New contrast agents

  4. MRA - TOF : Time-Of-Flight Blood Flow Signal Partially Saturated Spins v1 >v2 >v3 Saturated Static Tissue v1 v2 v3 tn = THK / vn (n=1,2,3) TR Slab THK t1 t2 t3 Fresh Inflow d=v TR Static Tissue Signal vessel v TR blood flow TR : Repetition time

  5. Acquisition Techniques • RF Coils • Reduce electric coupling, reduce noise figure • Pulse Sequences • Variable echo time • Double echo 3D TOF • Segment blood from tissue • Post processing noise reduction • 3D PR for ultrashort echo time (TE) • Novel Black-Blood sequences for carotid artery

  6. MRI Projects:3D TOF Complete FC + Variable Echo Time (VTE) • Eun Kee Jeong Non-VTE with Complete FC VTE with Complete FC

  7. Efficient Double Inversion FSE • DL Parker, EK Jeong, SE Kim, Eugene Kholmovski

  8. MRI Projects: Carotid Imaging Free Slices • Triple Double FSE: Interleaved Double Inversion Double Echo Non-interleaved acquisition. Interleaved acquisition.

  9. MRI Research: Carotid Imaging • Triple Double FSE: Interleaved Double Inversion Double Echo • Eugene: Triple Contrast: Interleaved Double Inversion Double Echo with interleaved T1

  10. Outline • Acquisition Techniques • RF coils, Pulse sequences, Field strength • Post Processing • Vessel enhancement, noise reduction techniques • Vessel Segmentation • Aneurysm Screening • New contrast agents

  11. Post ProcessingBrian Chapman • Noise Reduction • Vessel Enhancement Filtering

  12. Original vs. Filtered vs. Noise

  13. Post ProcessingEugene Kholmovski • Noise Reduction • Image Redundancy

  14. Original PD Original T2 Corrected PD Corrected T2 Spectral energy (non-image support) Double Echo FSE Motion Artifact Reduction • Eugene Kholmovski

  15. Standard Image POCS SENSE Reduction = 2, Ncoils = 4 Eugene Kholmovski

  16. Standard SENSE POCS SENSE Reduction = 4, Ncoils = 4 Eugene Kholmovski

  17. Outline • Acquisition Techniques • RF coils, Pulse sequences, Field strength • Post Processing • Vessel enhancement, noise reduction techniques • Vessel Segmentation • Aneurysm Screening • New contrast agents

  18. Conventional MIP Depth (Z-)Buffer Image Z-Buffer Segmentation (ZBS) Algorithm

  19. Future Segmentation • Incorporate Additional Information • Directionality • Signal intensity continuity • Segment the segmentation • Centerline recognition • Label vessel segments • Shape descriptors (tortuosity) • Use sparse vessel locations to speedup 3D PC and 2D PC techniques.

  20. Outline • Acquisition Techniques • RF coils, Pulse sequences, Field strength • Post Processing • Vessel enhancement, noise reduction techniques • Vessel Segmentation • Aneurysm Screening • New contrast agents

  21. High Resolution MRA Applications to Aneurysm Screening 3 Aneurysms, without (left) and with (right) Gadolinium Contrast. Parker, Tsuruda, et al., University of Utah

  22. Aneurysm Screening Pedigrees

  23. MRA Aneurysm Screening Results • Screening of high risk families • 143 high-risk intracranial aneurysm pedigrees found • 3400 total members • 340 relatives screened with MRA (29 aneurysms detected) • Evidence for a gene detected Dennis L. Parker, University of Utah

  24. Outline • Acquisition Techniques • RF coils, Pulse sequences, Field strength • Post Processing • Vessel enhancement, noise reduction techniques • Vessel Segmentation • Aneurysm Screening • New contrast agents

  25. General Focus • Goal to increase visibility of vascular disease • Aneurysms, embolic disease, atherosclerosis • Improve efficiency in MRA • Increase signal, post processing for noise reduction. • Use MRA for longitudinal studies of disease • Aneurysm Screening, carotid disease • New contrast agents • Blood pool, targeted agents

  26. Signal Regrowth Mz T1 (slow ~ 1s) Blood T2 should appear Longer than tissue T2 Mx My T2 (fast ~ 100ms)

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