Follow-up of intracranial aneurysms selectively treated with coils: Prospective evaluation of contrast-enhanced MR angiography

Abstract

Background and purpose: The aim of this study was to determine the feasibility and usefulness of contrast-enhanced MR angiography (CE-MRA) for the follow-up of intracranial aneurysms treated with detachable coils, by comparing CE-MRA with digital subtraction angiography (DSA) and 3D time-of- flight (TOF) MRA.

Methods: Thirty-two patients with 42 treated aneurysms were included in the study; 6 had been treated for multiple aneurysms. All MRAs were performed with a 1.5T unit within 48 hours of DSA. We performed 2 types of acquisition: a 3D TOF sequence and CE-MRA. Twenty-eight patients were included 1 year after endovascular treatment, and 4 patients, after 3 years or more. DSA was the technique of reference for the detection of a residual neck or residual aneurysm.

Results: Compared with DSA, the sensitivity of MRA was good. For the detection of residual neck, there was no significant difference between the results of 3D TOF MRA (sensitivity, 75%-87.5%; specificity, 92.9%, according to both readers) and CE-MRA (sensitivity, 75%-82.1%; specificity, 85.7%-92.9%). For the detection of residual aneurysm, sensitivity and specificity of both techniques were the same, respectively 80%-100% and 97.3%-100%. Therefore, CE-MRA was not better than 3D TOF MRA for the detection of residual neck or residual aneurysm. For large treated aneurysms, there was no difference between decisions regarding further therapy after CE and 3D TOF MRA, even though CE-MRA with a short echotime and enhancement gave fewer artifacts and better visualization of recanalization than 3D TOF MRA. The interpretation of transverse source images and the detection of coil mesh packing seemed easier with 3D TOF imaging.

Conclusion: This prospective study did not show that CE-MRA was significantly better than 3D TOF MRA for depicting aneurysm or neck remnants after selective endovascular treatment using coils. For aneurysms treated with coils, 3D TOF MRA seems a valid and useful technique for the follow-up of coiled aneurysms.

Figures

Fig 1.

Top of right carotid ophthalmic aneurysm treated by endovascular coiling in a 49-year-old woman. A, 3D TOF MRA transverse source image shows a hypersignal around the aneurysm (arrow). B, 3D TOF MIP anterior projection shows a hypersignal in the projection of the packing coil. C, DSA right carotid angiogram, lateral view, shows no recanalization of the sac. Magnetic susceptibility was responsible for unclear TOF MRA imaging.

Fig 2.

Left middle cerebral artery aneurysm 3 mm wide treated by endovascular coiling. Note a residual aneurysm (arrow). A and B, 3D TOF MRA transverse source image and MIP anterior projection show the clear visualization of the small treated aneurysm and remnant flow. C and D, CE-MRA source image and MIP anterior projection show that the packing coil is difficult to locate because venous enhancement affects image interpretation. E, DSA left carotid angiogram, anterior view, shows residual aneurysm.

Fig 3.

Giant aneurysm with no neck, incompletely treated with coils. A large residual flow is present inside the aneurysmal sac. A, 3D TOF transverse source image shows that the signal intensity inside the treated giant aneurysm (arrow) is degraded. The limits of residual flow are not clear between the strong flow signal intensity, the intermediate slow or turbulent flow signal intensity, and the intermediate blood clot signal intensity. B and C, CE-MRA source image and MIP anterior projection show that the remnant aneurysm is clearly defined and the visualization of the carotid branch conformation with the aneurysm is better. D, DSA right carotid angiogram, anterior view, shows large residual aneurysm.

Fig 4.

Source imaging shows treated aneurysm of the right posterior communicating artery. A, 3D TOF MRA transverse source image affords clear visualization of the low signal intensity of the coiling pack and the presence of a residual neck (arrow), but with CE-MRA source image (B), no delimitation is possible. DSA image confirms the presence of a residual neck (arrow, C).

Fig 5.

In a 25-year-old woman, a ruptured top carotid aneurysm treated during the acute phase by total occlusion and follow-up imaging 1 year later. A, 3D TOF MIP anterior projection. B, Contrast-enhanced MR MIP anterior projection. C, DSA intracranial right carotid TOF MRA and CE-MRA (B) show concordant findings in agreement with those of DSA. DSA imaging confirms the presence of a residual neck.