Intracranial aneurysms treated with Guglielmi detachable coils: is contrast material necessary in the follow-up with 3D time-of-flight MR angiography?

Abstract

Background and purpose: Three-dimensional time-of-flight (TOF) MR angiography has been evaluated in the follow-up of intracranial aneurysms treated with Guglielmi detachable coils (GDCs) with good results. Some of the studies used contrast material in addition to the 3D TOF MR technique and others did not. We assessed the usefulness of contrast material with 3D TOF MR angiography by comparing this sequence before and after contrast material injection.

Methods: Fifty-eight patients harboring a total of 71 cerebral aneurysms previously treated with GDCs were included in the prospective study. MR angiography (at 1.5 T) was performed with a 3D TOF sequence before and after injection of gadolinium-based contrast material. Features evaluated were presence and size of a neck remnant, parent and adjacent vessel patency, and venous overlap. Digital subtraction angiography was the standard of reference.

Results: Comparison of the techniques showed a good agreement in the detection of residual flow. Six cases of small residual neck were not detected with either the 3D TOF or the contrast-enhanced 3D TOF sequence. In one case of giant aneurysm, the extent of recanalization was more evident after contrast material administration. The use of contrast material did not help to show the parent and adjacent arteries. Venous overlap on contrast-enhanced 3D TOF angiograms did not affect image interpretation.

Conclusion: In this series, the use of intravenous contrast material did not improve the ability of 3D TOF MR angiography to depict the presence of residual or recurrent aneurysms previously treated with endovascular coiling. In one giant aneurysm, use of intravenous contrast material did result in improved visualization of a residual aneurysm.

Fig 1.

Recurrent communicating posterior aneurysm partially treated initially with a surgical clip and secondarily with coils. A, DSA lateral projection image obtained 1 year after GDC treatment shows an aneurysm remnant (arrow). B and C, Three-dimensional TOF (B) and contrast-enhanced 3D-TOF (C) images obtained with MIP reconstruction depict the same remnant cavity (arrow). On both MR angiograms, loss of signal intensity is noted at the internal carotid artery level above the aneurysm due to an artifact from the surgical clip. On the contrast-enhanced 3D TOF image, there is a enhancement of the cavernous sinus that does not preclude aneurysm analysis.

Fig 2.

Discrepancy between DSA and MR angiography. A, DSA oblique projection image of the right internal carotid artery obtained 3 months after treatment of a aneurysm in the anterior communicating artery shows a 2-mm remnant in the aneurysm neck (arrow). B and C, Three-dimensional TOF (B) and contrast-enhanced 3D TOF (C) images with MIP reconstruction in the frontal view do not depict the aneurysm remnant.

Fig 3.

Ruptured giant internal carotid artery aneurysm partially treated with endovascular placement. A, DSA image, lateral projection, after left internal carotid injection obtained 3 months after treatment shows the partially packed aneurysm (arrow). B and C, Lateral MIP reconstruction (B) and axial 3D TOF source MR angiogram (C) underestimate the size of the aneurysm remnant (arrow). D and E, Contrast-enhanced lateral MIP reconstruction (D) and axial 3D TOF source MR angiogram (E). Contrast material administration allows a better delineation and identification of the aneurysm remnant (arrows).

Fig 4.

Wide-neck basilar tip aneurysm treated with assistance from a neck-bridge device. A, DSA image (Towne projection) after right vertebral artery injection shows the aneurysm before embolization. B and C, DSA images (Towne projection) obtained 1 year after embolization show subtotal occlusion of the aneurysm. There is only a 2-mm remnant neck (arrow in C), with patency of the left posterior artery. D, Nonsubstracted DSA image after left vertebral artery injection. The arrow points to the stem marker of the neck-bridge device used during treatment. E and F, Both 3D TOF (E) and contrast-enhanced 3D TOF (F) images obtained with MIP reconstruction depict the small remnant neck (arrow). Loss of signal intensity is noted at the origin of the posterior cerebral and superior cerebellar arteries surrounding the Trispan coil stem. The addition of contrast material does not improve the quality of the images.