Topics in Magnetic Resonance Angiography Research and Some Potential New Directions

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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 - PowerPoint PPT Presentation

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