Stability of intracranial aneurysms adequately occluded 6 months after coiling: a 3T MR angiography multicenter long-term follow-up study

Abstract

Background and purpose: The long-term fate of coiled intracranial aneurysms is largely unknown, and prolonged imaging follow-up has been advocated. The yield of follow-up imaging in coiled aneurysms adequately occluded at 6 months is unknown. In such patients, we performed time-of-flight MR angiography (MRA) to assess the incidence and therapeutic consequences of reopening 5-11 years after coiling.

Materials and methods: Between 1995 and 2002, 661 aneurysms in 607 patients were coiled in 3 participating centers. Six-month follow-up angiograms were obtained in 497 (75%) aneurysms, of which 316 (64%) in 297 patients were adequately occluded. Of 297 patients, 84 were excluded for various reasons and 73 could not be traced. Of 140 eligible patients, 104 (74%) with 111 aneurysms were studied with 3T MR imaging and high-resolution MRA at a mean of 6.0 years after coiling (median, 5.6 years; range, 5.0-10.6 years).

Results: The proportion of aneurysms with reopening was 3.6% (4/111; 95% confidence interval [CI], 1.1%-9.2%). One reopened aneurysm, which initially contained intraluminal thrombus, was additionally coiled (0.9%; 95% CI, 0.0%-5.4%).

Conclusion: In intracranial aneurysms with adequate occlusion at 6 months after coiling, the proportion of reopening needing retreatment after >5 years is low. The number of reopened aneurysms with therapeutic consequences was too small to assess risk factors, but probably the presence of intraluminal thrombus is one such risk factor. Most patients with coiled intracranial aneurysms that are adequately occluded at 6 months might not need prolonged imaging follow-up.

Fig 1.

Flow chart of total cohort and included aneurysms.

Fig 2.

A 61-year-old woman with a ruptured 3-mm middle cerebral artery aneurysm. A, Precoiling angiogram shows a small aneurysm. B, Complete occlusion after coiling. C, Stable complete occlusion at 6 months. D, MRA at 7.3 years demonstrates a 1 × 2 mm intraluminal opening inside the coil mesh classified as a recurrence (arrow).

Fig 3.

A 54-year-old woman with a ruptured 5-mm basilar tip aneurysm. A, Precoiling vertebral angiogram shows a basilar tip aneurysm. B, Stable complete occlusion at 6 months. C, Angiogram at 5.8 years shows a 2 × 3 mm disklike recurrence at the base of the aneurysm. D, MRA at 8.0 years is unchanged, compared with the last angiogram.

Fig 4.

A 49-year-old woman with a ruptured 10-mm basilar tip aneurysm. A, Precoiling vertebral angiogram demonstrates the basilar tip aneurysm with a small bleb on its base (arrow). B, On the angiogram immediately postcoiling, the bleb (arrow) is not occluded. C, Unchanged open bleb (arrow) at 6 months. D, Angiogram at 5.5 years with recurrence (arrow) at the base from the bleb. E and F, MRA overview (E) and detail (F) at 8.1 years demonstrate unchanged recurrence (arrow).

Fig 5.

A 66-year-old man presenting with seizures with an unruptured left middle cerebral artery aneurysm. A, Precoiling angiogram. B, Complete occlusion after coiling. C, Stable complete occlusion at 6 months. D, MRA at 6.6 years shows a 6 × 4 mm recurrence (arrow). E, Angiogram before the second coiling. F, After the second coiling, again complete occlusion is seen. G, Six months after the second coiling, repeat reopening of the aneurysm is noted. H, After the third coiling, again complete occlusion is seen. Note that the coil mesh is much larger than the aneurysmal lumen in A. I, Initial CT angiography before the first coiling demonstrates thrombus surrounding the aneurysm lumen and perifocal edema. J, MR imaging at 6.6 years shows migration of the coil mesh in the thrombosed part of aneurysm and a perianeurysmal cyst.