Image-Quality Analysis of TOF-MRA and Silent MRA The difference between the TOF-MRA and silent MRA, in combination with FSE-MRC, was directly compared in each case. We were thus able to directly compare the shape of the aneurysmal neck complex with/without neck remnants depicted by the 2 types of MRA combined with the coiled dome shown by MRC.
The overall time required to reconstruct a picture of 3D multifusion imaging was within 120 seconds per image. To visualize the 2 types of MRA images in combination with MRC images in a single 3D image, we used 3D multifusion imaging by compositing the above-described reconstructed 3D images of TOF-MRA, silent MRA, and FSE-MRC. The perspective volume-rendering image of the 3D FSE-MRC was reconstructed from the entire dataset with a lower signal intensity of CSF (threshold, <1200) so that the shape of the coiled aneurysmal dome and parent artery complex was delineated with its perianeurysmal anatomic structures, including the brain parenchyma and cranial nerves. Thus, the 3D image of parent arteries and aneurysmal neck after coiling was depicted by the 2 types of MRA. 13 ⇓– 15 For the 3D TOF-MRA and silent MRA, the vessel configurations were reconstructed by a perspective volume-rendering algorithm, and the arterial lumen was selected from the opacity chart of the datasets with higher MR signal intensity of arteries (threshold, >400 for TOF-MRA and >300 for silent MRA, respectively) compared with the background. Volumetric datasets from the source images of the TOF-MRA, silent MRA, and FSE-MRC were transferred to a workstation (Ziostation-2 Ziosoft/AMIN, Tokyo, Japan) as described by Satoh et al. A total of 60 continuous axial source images were acquired. The heavily T2-weighted 3D FSE-MRC was performed with the following parameters: TR/TE, 1900/100 ms FOV, 180 × 180 mm matrix, 356 × 256 section thickness, 1.2 mm NEX, 1 bandwidth, 31.25 kHz echo-train length, 128 acquisition time, 5 minutes 53 seconds. A total of 400 continuous axial source images were acquired. The silent MRA was performed by a silent scan with the following parameters: TR/TE, 880/0.016 ms flip angle, 5° FOV, 180 × 180 mm matrix, 200 × 200 spokes per segment, 320 section thickness, 1.0 mm NEX, 1.5 bandwidth, 31.25 kHz acquisition time, 12 minutes 48 seconds. A total of 144 continuous axial source images were acquired. The TOF-MRA was performed with the following parameters: TR/TE, 25/3.4 ms flip angle, 20° FOV, 180 × 180 mm matrix, 288 × 192 section thickness, 1.2 mm NEX, 1 bandwidth, 35.71 kHz acquisition time, 5 minutes 41 seconds. The imaging by TOF-MRA, silent MRA, and FSE-MRC was performed in the same session on a 3T unit (Signa Pioneer GE Healthcare, Milwaukee, Wisconsin). To the best of our knowledge, the delineation of the coiled neck with 3D silent MRA and the dome with 3D FSE-MRC, and 3D multifusion imaging of these structures in a single 3D image has not been described. 13 ⇓– 15 In the present study, we used 3D multifusion imaging with silent MRA-instead of TOF-MRA-and FSE-MRC to delineate the configuration of the aneurysmal neck and dome after coiling treatment of cerebral aneurysms. 2, 7, 9, 10, 12 In addition, MR cisternography (MRC) with a heavily T2-weighted 3D FSE sequence can depict the shape of the aneurysmal dome together with perianeurysmal anatomic structures, including the brain parenchyma and cranial nerves. With some recent advances in MR imaging, it has been speculated that silent MRA with zero-TE and arterial spin-labeling tagging may overcome the above problems by delineating flowing blood at the neck with minimal artifacts from metal substances. 2, 5 ⇓– 7, 9, 10 As a noninvasive substitute for DSA, 3D TOF-MRA with/without contrast media is widely used, but this method presents some difficulty regarding magnetic susceptibility artifacts from the coils. 1 ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓– 11 X-ray DSA is a reference standard to examine the above-described configuration, but it is invasive and presents certain risks related to the catheter procedure, contrast media, and radiation. In the follow-up after the endovascular treatment of a cerebral aneurysm, the precise visualization of the shape of the neck and dome with/without remnants from coiling is necessary. ABBREVIATIONS: AComA anterior communicating artery MRC MR cisternography