Noninvasive Imaging of Treated Cerebral Aneurysms, Part I: MR Angiographic Follow-Up of Coiled Aneurysms

A, Conventional left internal carotid angiogram demonstrates a tiny 1- to 2-mm residual neck at the base of a coiled anterior communicating artery aneurysm. B, Correlative MIP projection from a TOF-MRA accurately demonstrates this tiny residual.

A, Conventional right internal carotid angiogram depicts a coil mass within a right carotid terminus aneurysm. A tiny (2-mm) residual aneurysm (arrow) is evident only as a double attenuation overlapping the parent vessel. On the other A-plane angiographic views, this small residual projected over the coil mass and was obscured. On the lateral projections, the residual was obscured by overlying anterior cerebral artery and middle cerebral artery branches. B–D, Correlative TOF-MRA source images demonstrate that the tiny residual arises from the anterior aspect of the aneurysm neck and projects superiorly along the anterior aspect of the coil mass (arrows). In retrospect, it can be appreciated just how this small residual would be obscured by either the coil mass or adjacent vessels on the most angiographic projections. E, An image from a rotational angiogram with the coil mass attenuation mapped to a blue color provides additional evidence of the tiny residual at the base of the coil mass, projecting superiorly from the anterior aneurysm neck.

A, Conventional angiogram demonstrates a small right posterior communicating artery aneurysm after coil embolization. The unsubtracted image (left) depicts a tail of coil projecting anteriorly (arrow). The subtracted image (right) demonstrates that this coil tail projects toward the parent artery from which the aneurysm arises. A small amount of filling between the interstices of the coil mass is also noted along the anterior aspect of the aneurysm neck. B, Correlative TOF-MRA source image demonstrates the coil mass as a signal-intensity void. A linear signal-intensity void (arrow) projects anteriorly into the parent posterior communicating artery corresponding to the coil tail visualized on the native image. The small pocket of residual filling is also appreciated along the lateral aspect of the coil mass. Reading the MRA without the posttreatment angiographic correlation could lead to confusion with respect to the interpretation of these structures in the region of the aneurysm neck. A correlation of the 2 techniques provides a detailed and complimentary understanding of the anatomy in this region.

A, Axial source image from a contrast-enhanced MRA unambiguously demonstrates a tiny (<2-mm) residual superior hypophyseal-region aneurysm (arrow). B, Correlative left internal carotid conventional angiogram shows that this tiny pocket of residual filling (arrow) is surrounded by strands of coil.

Axial source images from a contrast-enhanced MR image obtained immediately after treatment (left image) demonstrate no enhancement about the posterior aspect of a large basilar aneurysm coil mass (arrows). Follow-up imaging performed 6 weeks later (right image) demonstrates the interval development of a thin rim of enhancement marginating the posterior aspect of the coil mass (arrows). This pattern of enhancement is not representative of recanalization but more likely of mural enhancement as a sequela of the in-growth of granulation tissue about the periphery of the coil mass.