MR angiography at 3T versus digital subtraction angiography in the follow-up of intracranial aneurysms treated with detachable coils

Abstract

Background and purpose: Digital subtraction angiography (DSA) is used to follow-up intracranial aneurysms treated with detachable coils to identify recurrence and determine need for additional treatment. However, DSA is invasive and involves a small risk of neurologic complications. We assessed the feasibility and usefulness of 3D time-of-flight (TOF) MR angiography (MRA) performed at 3T compared with DSA for the follow-up of coil-treated intracranial aneurysms.

Methods: In a prospective study, 20 consecutive patients with 21 intracranial aneurysms treated with coils underwent DSA and nonenhanced and enhanced multiple overlapping thin-slab acquisition 3D TOF MRA at 3T on the same day at a mean follow-up of 6 months (range, 4-14 months) after coil placement. MRA images were evaluated for presence of artifacts, presence and size of aneurysm remnants and recurrences, patency of parent and branch vessels, and added value of contrast material enhancement. MRA and DSA findings were compared.

Results: Interobserver agreement of MRA was good, as was agreement between MRA and DSA. All three recurrences that needed additional treatment were detected with MRA. Minor disagreement occurred in four cases: three coil-treated aneurysms were scored on MRA images as having a small remnant, whereas on DSA images these aneurysms were occluded; the other aneurysm was scored on MRA images as having a small remnant, whereas on DSA images this was a small recurrence. Use of contrast material had no additional value. Coil-related MR imaging artifacts were minimal and did not interfere with evaluation of the occlusion status of the aneurysm.

Conclusion: High-spatial-resolution 3D TOF MRA at 3T is feasible and useful in the follow-up of patients with intracranial aneurysms treated with coil placement.

Fig 1.

Interobserver disagreement on MRA and disagreement between MRA and DSA on the occlusion of a basilar tip aneurysm after treatment with coils. A, DSA image obtained immediately after treatment with coils shows complete aneurysm occlusion. B, Nonenhanced MOTSA 3D TOF MRA image obtained 5 months after treatment shows filling of the aneurysm neck (arrow), which was interpreted by one observer as a 2-mm remnant and by the other observer as a 2-mm recurrence. During the consensus reading, it was scored as a remnant. Note minor signal intensity loss in the proximal P1 segment of the left posterior cerebral artery. C, DSA image obtained 5 months after treatment with coils. This image was interpreted as occlusion.

Fig 2.

Posterior communicating artery aneurysm with small neck remnant 7 months after treatment with coils. A, Axial nonenhanced MOTSA 3D TOF MRA source image demonstrates a 2-mm neck remnant (arrow). B, Nonenhanced MOTSA 3D TOF MR target maximum intensity projection image also shows a small neck remnant (arrow). C, DSA image confirms the presence of a small neck remnant (arrow).

Fig 3.

Middle cerebral artery aneurysm with high-signal-intensity rim artifact and recurrence 6 months after treatment with detachable coils. A, Axial fast spin-echo T2-weighted MR image (3394/80) shows a 2-mm rim of increased signal intensity around the coils (arrow). B, Axial nonenhanced MOTSA 3D TOF MRA source image demonstrates recurrence of the aneurysm (arrow). C, Nonenhanced MOTSA 3D TOF MRA image shows recurrence (arrow). D, Contrast-enhanced MOTSA 3D TOF MRA image shows the same recurrence (arrow). E, DSA image obtained 6 months after treatment confirms the presence of recurrence (arrow).

Fig 4.

Anterior communicating artery aneurysm with recurrence 8 months after treatment with coils. A, DSA image shows large anterior communicating artery aneurysm. B, DSA image shows complete occlusion after coiling. C, Axial nonenhanced MOTSA 3D TOF MRA source image obtained 8 months after treatment demonstrates recurrence (arrow). D, Nonenhanced MOTSA 3D TOF MRA image demonstrates recurrence (arrow). E, DSA image obtained 8 months after treatment confirms the presence of recurrence due to coil compaction (arrow).

Fig 5.

Disagreement between MRA and DSA on the occlusion status of a posterior inferior cerebellar artery aneurysm 14 months after treatment with coils. A, DSA image obtained immediately after coiling shows a small area of residual filling (arrow). B, Nonenhanced MOTSA 3D TOF MRA image obtained 14 months after treatment shows flow in the aneurysm neck (arrow), which was interpreted as a 2-mm remnant by both observers. C, DSA image shows filling of the aneurysm neck (arrow), which was interpreted as a 2-mm recurrence (including a 1-mm remnant) due to coil compaction. Both observers thought that additional treatment for this small recurrence was not indicated.

Fig 6.

Anterior communicating artery aneurysm with coil-related signal intensity loss in parent and branch vessels. A, Axial nonenhanced MOTSA 3D TOF MRA source image obtained 8 months after treatment shows narrowing of the anterior communicating artery (arrow). No neck remnant or aneurysm recurrence was found. B, Nonenhanced MOTSA 3D TOF MRA image shows narrowing of the anterior communicating artery (arrow) and the proximal part of both A2 segments of the anterior cerebral arteries (arrowheads). C, Enhanced MOTSA 3D TOF MRA image shows similar narrowings as described in B. D, DSA image shows complete occlusion of the aneurysm without narrowing of parent and branch vessels.