Topics in Magnetic Resonance Angiography Research and Some Potential New Directions
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Transcript of 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
• Aneurysm Screening
• New contrast agents
Outline
• Acquisition Techniques• RF coils, Pulse sequences, Field strength
• Post Processing• Vessel enhancement, noise reduction techniques
• Vessel Segmentation
• Aneurysm Screening
• New contrast agents
MRA - TOF : Time-Of-Flight
Slab THK
blood flow
vessel
Partially Saturated Spins
v
Saturated Static Tissue
d=v TR
TR
v3
v2v1
v1 >v2 >v3
tn = THK / vn (n=1,2,3)
t3t2t1
Blood Flow Signal
TR
Static Tissue Signal
FreshInflow
TR : Repetition time
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
MRI Projects:3D TOF Complete FC +
Variable Echo Time (VTE) • Eun Kee Jeong
Non-VTE with Complete FC VTE with Complete FC
Efficient Double Inversion FSE
• DL Parker, EK Jeong, SE Kim, Eugene Kholmovski
MRI Projects: Carotid Imaging• Triple Double FSE:
Interleaved Double Inversion Double Echo
Non-interleaved acquisition.Interleaved acquisition.
FreeSlices
MRI Research: Carotid Imaging• Triple Double FSE: Interleaved Double Inversion
Double Echo
zslice
zni
zinterl eaved
Artery Segment
Slice N+1Slice 1
• Eugene: Triple Contrast: Interleaved Double Inversion Double Echo with interleaved T1
Outline
• Acquisition Techniques• RF coils, Pulse sequences, Field strength
• Post Processing• Vessel enhancement, noise reduction techniques
• Vessel Segmentation
• Aneurysm Screening
• New contrast agents
Post ProcessingBrian Chapman
• Noise Reduction
• Vessel Enhancement Filtering
Original vs. Filtered vs. Noise
Post ProcessingEugene Kholmovski
• Noise Reduction
• Image Redundancy
Double Echo FSE Motion Artifact Reduction
• Eugene Kholmovski
Original PD Original T2
Spectral energy (non-image support)
Corrected PD Corrected T2
Standard Image POCS SENSE
Reduction = 2, Ncoils = 4
Eugene Kholmovski
Standard SENSE POCS SENSE
Reduction = 4, Ncoils = 4
Eugene Kholmovski
Outline
• Acquisition Techniques• RF coils, Pulse sequences, Field strength
• Post Processing• Vessel enhancement, noise reduction techniques
• Vessel Segmentation
• Aneurysm Screening
• New contrast agents
Z-Buffer Segmentation (ZBS) Algorithm
Conventional MIP Depth (Z-)Buffer Image
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.
Outline
• Acquisition Techniques• RF coils, Pulse sequences, Field strength
• Post Processing• Vessel enhancement, noise reduction techniques
• Vessel Segmentation
• Aneurysm Screening
• New contrast agents
High Resolution MRA Applications to Aneurysm Screening
3 Aneurysms, without (left) and with (right) Gadolinium Contrast. Parker, Tsuruda, et al., University of Utah
Kindred 7450
2 2
2
S38
105
S61
110
FAM
117
FAM
10 9
MR
1
S34
5
S41
6
S45
7
S42
15
S0
16
FAM
S47
26
MR 39
S48
21
S38
104 103
FAM
115 116
11 8
S71
13
S71
12 18
S69
17
S77
96 97 98 96
4 3
94 95
Aneurysm Screening Pedigrees
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
Outline
• Acquisition Techniques• RF coils, Pulse sequences, Field strength
• Post Processing• Vessel enhancement, noise reduction techniques
• Vessel Segmentation
• Aneurysm Screening
• New contrast agents
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
MzT1 (slow ~ 1s)
Signal Regrowth
MxMy
T2 (fast ~ 100ms)
Blood T2 should appear Longer than tissue T2