Contrast-enhanced time-resolved MRA for follow-up of intracranial aneurysms treated with the pipeline embolization device

Abstract

Background and purpose: Endovascular reconstruction and flow diversion by using the Pipeline Embolization Device is an effective treatment for complex cerebral aneurysms. Accurate noninvasive alternatives to DSA for follow-up after Pipeline Embolization Device treatment are desirable. This study evaluated the accuracy of contrast-enhanced time-resolved MRA for this purpose, hypothesizing that contrast-enhanced time-resolved MRA will be comparable with DSA and superior to 3D-TOF MRA.

Materials and methods: During a 24-month period, 37 Pipeline Embolization Device-treated intracranial aneurysms in 26 patients underwent initial follow-up by using 3D-TOF MRA, contrast-enhanced time-resolved MRA, and DSA. MRA was performed on a 1.5T unit by using 3D-TOF and time-resolved imaging of contrast kinetics. All patients underwent DSA a median of 0 days (range, 0-68) after MRA. Studies were evaluated for aneurysm occlusion, quality of visualization of the reconstructed artery, and measurable luminal diameter of the Pipeline Embolization Device, with DSA used as the reference standard.

Results: The sensitivity, specificity, and positive and negative predictive values of contrast-enhanced time-resolved MRA relative to DSA for posttreatment aneurysm occlusion were 96%, 85%, 92%, and 92%. Contrast-enhanced time-resolved MRA demonstrated superior quality of visualization (P = .0001) and a higher measurable luminal diameter (P = .0001) of the reconstructed artery compared with 3D-TOF MRA but no significant difference compared with DSA. Contrast-enhanced time-resolved MRA underestimated the luminal diameter of the reconstructed artery by 0.965 ± 0.497 mm (27% ± 13%) relative to DSA.

Conclusions: Contrast-enhanced time-resolved MRA is a reliable noninvasive method for monitoring intracranial aneurysms following flow diversion and vessel reconstruction by using the Pipeline Embolization Device.

Fig 1.

Stent migration with concordance between CE-TR MRA and DSA. A 56-year-old woman with a right cavernous carotid aneurysm. A, Immediate post-PED of the right cavernous ICA aneurysm with stasis. B, DSA shows the actual position of the PED after embolization (yellow line along stent course). C, Complete opacification of the aneurysm at 6-month DSA with no stasis or thrombus. D, DSA confirms distal migration (yellow line along stent course) resulting in reopening of the aneurysm neck (red line with red arrow). Superior demonstration of complete aneurysm opacification (yellow arrow) on CE-TR MRA (F) over 3D-TOF MRA (E) at 6-month follow-up. The hyperintensity in the aneurysm sac on TOF MRA (E) may represent either thrombus from intact PED or aneurysm refilling from PED migration (yellow arrow).

Fig 2.

Discordance between CE-TR MRA and DSA. A 68-year-old woman with a right paraophthalmic aneurysm. A, Post-Pipeline embolization right paraophthalmic aneurysm. B, No residual neck is demonstrated (yellow arrow) on the 6-month follow-up CE-TR MRA. C, A thin crescentic residual neck measuring 1 mm deep (yellow arrow) is seen on the subsequent DSA.

Fig 3.

Overestimation of in-stent stenosis on MRA techniques. A 63-year-old woman with a left ophthalmic artery aneurysm. A, 3D-TOF MRA shows complete loss of flow-related enhancement in the PED (yellow arrow), suggestive of occlusion. B, Preserved enhancement within the PED with a narrowed lumen (yellow arrow) suggestive of in-stent stenosis. C, DSA demonstrates a normal-caliber ICA with no in-stent stenosis or occlusion.