MRA acquisition

Contrast-enhanced MRA at 3T
Signal ratio: contrast-enhanced arterial blood – fat tissue
T 1
arterial blood
T 1
fat
R 1
Magnevist
T 1
blood + Gad (5 mmol/L)
Signal ratio blood/fat
TR=3.5 ms, a = 30°, C blood
= 5 mmol/L
1.5 T
1250 ms
343 ms
4.1 L/mmol/s
47 ms
5.15
3.0 T
1650 ms
382 ms
3.7 L/mmol/s
52 ms
5.30
High-resolution MRA @ 3 Tesla
1.5T MRA
3.0T MRA
TR / TE [ms]
3.77 / 1.39
3.14 / 1.1
Flip angle [°]
25
23
Bandwidth [Hz/Px] ∆: 1.5T 3.0T350
510
Matrix
512 x 80%
Voxel volume -28%
512 x 80%
FOV [mm²]
400 x 87%
400 x 81%
Slab thickness +8%
Phase Oversampling [%]
0
8
Voxel size [mm³] Scan time 0.8 -6%
0.65
Spatial resolution [mm³]
1 x 0.8 x 1
0.9 x 0.8 x 0.9
Better background (fat) suppression for MRA
Higher vessel contrast!
Decrease contrast amount by 10%-20%
Scan time [s]
19
Partitions
80
Parallel imaging
GRAPPA factor 3
Michaely HJ, Nael K et al. Rofo. 2005; 177: 800-804
18
96
GRAPPA factor 3
From spatial to temporal resolution
1.5T
3.0T
Spatial resolution 1.4 x 1.4 x 1.5 mm, 10 ml CM
3.7 s (PAT3) Temporal Resolution 2.9 s (PAT4)
3T
Michaely HJ, et al. Radiology 2007; 244: 907-913
Kramer H, et al.
Invest Radiol 2007; 42: 477-483
From spatial to temporal resolution
(2D-)PAT and image geometry
TWIST at 3 Tesla
Courtesy of Mike Notohamiprodjo MD and Christian Glaser MD, LMU Munich