Time-of-flight MR angiography targeted to coiled intracranial aneurysms is more sensitive to residual flow than is digital subtraction angiography.
OBJECTIVE
For intracranial aneurysms treated with Guglielmi detachable coils, long-term follow-up is mandatory because coil compaction may occur and aneurysms may recur. The purpose of this study was to establish a noninvasive technique to visualize residual flow in coiled aneurysms.


METHODS
We designed a 3D time-of-flight (3D-TOF) MR angiography (MRA) technique targeted to depict coiled aneurysms that employed a very short TE (1.54-1.60 ms) and a high spatial resolution (0.3 x 0.3 x 0.3 mm3 with zero-filling) to diminish spin dephasing. To diminish spin saturation, image volume was carefully positioned so that the neck of the targeted aneurysm was within 2 cm of the inflow portion along the stream of blood. Fifty-one MRA images of 39 coiled aneurysms in 39 patients were compared with digital subtraction angiography (DSA) images. DSA and MRA findings were interpolated retrospectively for parent and branch arteries' patency, as well as residual flow in aneurysms. In the latest 11 MR studies, a dark-blood 3D turbo spin-echo sequence was added to MRA to negate the effect high-signal-intensity thrombus.


RESULTS
MRA visualized all parent and branch arteries with DSA confirmation. MRA visualized residual flow more frequently (38 studies) than did DSA (25 studies). Residual flow space visualized with MRA was always similar to or larger than that with DSA. The dark-blood sequence completely suppressed intraluminal high signal intensity on MRA images and confirmed that the high signal intensity was not due to thrombus.


CONCLUSIONS
TOF MRA targeted to depict coiled intracranial aneurysms is noninvasive and superior to DSA in visualization of residual flow and, hence, useful for follow-up of coiled aneurysms.
Department of Radiology and Nuclear Medicine, National Cardiovascular Center, Osaka, Japan.
Naoaki
N
Yamada
Katsuhiko
K
Hayashi
Kenichi
K
Murao
Masahiro
M
Higashi
Koji
K
Iihara
D000368:Aged; D015901:Angiography, Digital Subtraction; D016477:Artifacts; D002533:Cerebral Angiography; D004621:Embolization, Therapeutic; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000628:therapy*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012039:Regional Blood Flow / Q000502:physiology; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014654:Vascular Patency / Q000502:physiology