1. Topics in Magnetic Resonance Angiography Research and 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 Slab THK blood flow vessel Partially Saturated Spins v Saturated Static Tissue d=v T R TRTR v3v3 v2v2 v1v1 v 1 >v 2 >v 3 t n = THK / v n (n=1,2,3) t3t3 t2t2 t1t1 Blood Flow Signal TRTR Static Tissue Signal Fresh Inflow T R : 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 FCVTE with Complete FC

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

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

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 Processing Brian Chapman Noise Reduction Vessel Enhancement Filtering

12. Original vs. Filtered vs. Noise

13. Post Processing Eugene Kholmovski Noise Reduction Image Redundancy

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

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. Z-Buffer Segmentation (ZBS) Algorithm Conventional MIPDepth (Z-)Buffer Image

20. 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.

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

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

23. Aneurysm Screening Pedigrees

24. 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

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

26. 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

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