No advantage of time-of-flight magnetic resonance angiography at 3 Tesla compared to 1.5 Tesla in the follow-up after endovascular treatment of cerebral aneurysms.
BACKGROUND
Long-term follow-up after coil embolization of intracranial aneurysms is mandatory to monitor coil compacting and aneurysm recurrence. Most centers perform one digital subtraction angiography (DSA) on follow-up continuing with time-of-flight magnetic resonance angiography (TOF-MRA). This study explores the diagnostic value of TOF-MRA at 1.5 T versus 3 T compared to DSA.


METHODS
In 18 patients with 20 aneurysms treated with coil embolization, TOF-MRA at 1.5 and 3 T were performed the day before follow-up DSA, the latter serving as reference. Optimized diagnostic protocols were applied (1.5 T: 0.78 x 0.55 x 0.8 mm, voxel size; acquisition time (TA), 6.37 min; 3 T: 0.56 x 0.45 x 0.65 mm, voxel size; TA, 3.12 min). Three independent neuroradiologists experienced in neuroendovascular therapy rated the occlusion rate ("complete occlusion" vs. "residual neck" vs. "residual aneurysm") and compared the two methods subjectively. Weighted kappa statistics were calculated to assess the level of interobserver agreement.


RESULTS
Compared to DSA, TOF-MRA was more sensitive in detecting neck remnants, with a slight advantage at 3 T. Regarding artifact load, there are advantages at 1.5 T. Ratings of the occlusion rate correlated highly between all observers (r > 0.85, p < 0.001, respectively). Interobserver agreement was high in all cases (small ka, Cyrillic (w) approximately 0.8, respectively).


CONCLUSIONS
TOF-MRA is a reliable tool for follow-up imaging of cerebral aneurysms after endovascular treatment. Our study shows no advantage of TOF-MRA at 3 T over 1.5 T, when comparable measurement protocols are applied. TOF-MRA at 1.5 T therefore provides appropriate information regarding a therapeutic decision.
Buhk
Jan-Hendrik
JH
Department of Neuroradiology, University of Göttingen, Robert-Koch-Str. 40, 37075, Goettingen, Germany. jbuhk@gwdg.de
Kallenberg
Kai
K
Mohr
Alexander
A
Dechent
Peter
P
Knauth
Michael
M
D000328:Adult; D000368:Aged; D015901:Angiography, Digital Subtraction; D004621:Embolization, Therapeutic / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000628:therapy*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome