Noninvasive Imaging of Treated Cerebral Aneurysms, Part II: CT Angiographic Follow-Up of Surgically Clipped Aneurysms

A, Axial source image through a surgical clip at the basilar tip demonstrates artifacts directed along the long axis of the clip as the result of the increased attenuation through that axis. B, The coronal multiplanar reconstruction image does not demonstrate many artifacts, despite the degradation of the axial source image, but the area immediately adjacent to the clip is not optimally imaged. C, With optimal threshold settings, in a 3D volume-rendered image viewed from the posterior and inferior aspect clips at the basilar tip, a small residual is evident (arrow), projecting off the left and posterior aspect of the aneurysm neck. Note that the orientation of this image is close to the projection for a Towne view routinely used for diagnostic evaluation of the posterior circulation, except that the CTA is being viewed from behind. D, Frontal “transfascial” view from catheter-based DSA demonstrates a double attenuation (arrow) that is suggestive of a residual aneurysm remnant. E, Towne view similar to the projection from the volume-rendered CTA, but now viewed from the front, demonstrates the small “dog ear” residual (arrow) on the left, measuring approximately 2 mm.

A, Axial source image at the level of 2 cobalt clips demonstrates significant artifacts that obscure the surrounding brain and vessels. Wider windows were used to minimize artifacts but resulted in poor vessel contrast differentiation. B, Axial source image through a series of 3 titanium aneurysm clips, with a fourth clip partially imaged, demonstrates minimal artifacts related to the titanium, and the parent vessel can easily be seen (arrow) with no evidence of residual aneurysm. C, 3D volume rendering demonstrates the 4 titanium clips and adjacent vessels without significant degradation by artifacts. D, Catheter angiogram demonstrates the original aneurysm before clip reconstruction.

A, 3D volume reformat of CTA demonstrates a bilobed anterior communicating aneurysm. B, Axial MPR image obtained in the perioperative period demonstrates a round contrast collection consistent with a residual aneurysm remnant (arrow) of the posterior lobe of the bilobed aneurysm. C, Sagittal reformat also demonstrates a similar finding (arrow) and better shows the relation to the aneurysm clips. D, 3D volume rendering of the same CTA data, viewed from the anterior and below, gives an easily identifiable angiographic appearance that shows the residual aneurysm remnant (arrow) and the relation to the parent vessel and clips. E, Follow-up angiogram of the right internal carotid artery obtained 1 week post-subarachnoid hemorrhage demonstrates the residual aneurysm lumen (arrow) as well as a vasospasm involving the supraclinoid internal carotid artery and A1 segment. F, After coil embolization of the aneurysm remnant (arrow), the angiogram shows no residual aneurysm.