To TOF or not to TOF: strategies for non-contrast-enhanced intracranial MRA at 7 T.
OBJECTIVE
The purpose of this study was to optimize and to evaluate 3D time-of-flight (TOF)-like non-contrast enhanced MR-angiography (MRA) techniques for display of the intracranial vessels on a 7 T whole-body scanner.


METHODS
Three different gradient echo sequences (TOF, VIBE, MPRAGE) were compared in 12 healthy volunteers and 13 patients. Two blinded senior radiologists independently rated the presence or absence of artefacts and the conspicuity of ten different vessel segments in source and maximum-intensity-projection (MIP) images.


RESULTS
In source images, MPRAGE achieved the best results; even the fine vessels and the vessels near the air-containing mastoid were depicted very well. Intraluminal signal loss, which was a problem in the greater vessels in TOF and VIBE imaging, was less pronounced in MPRAGE images. In the MIP images, TOF performed best. Both VIBE and MPRAGE can generate TOF-like contrast and cover the whole brain in less than 15 min, whereas TOF covered only a subvolume of the brain.


CONCLUSIONS
MPRAGE performed especially well in this 7 T imaging study. The accuracy of the sequence deserves further evaluation in patients with vessel stenoses and aneurysms.
Maderwald
Stefan
S
Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Arendahls Wiese 199, 45141 Essen, Germany. Stefan.Maderwald@uni-duisburg-essen.de
Ladd
Susanne C
SC
Gizewski
Elke R
ER
Kraff
Oliver
O
Theysohn
Jens M
JM
Wicklow
Karsten
K
Moenninghoff
Christoph
C
Wanke
Isabel
I
Ladd
Mark E
ME
Quick
Harald H
HH
D000328:Adult; D000368:Aged; D000783:Aneurysm / Q000175:diagnosis / Q000473:pathology; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000295:instrumentation* / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors; D051598:Whole Body Imaging / Q000379:methods