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MR evaluation of neurovascular lesions after endovascular occlusion with detachable balloons
E S Kwan1, S M Wolpert, R M Scott
1Department of Radiology, New England Medical Center Hospital, Boston, MA 02111.
Insights
This study evaluated magnetic resonance (MR) imaging for follow-up of endovascular embolization of carotid aneurysms. MR effectively tracks changes in thrombus and Cholografin-filled balloons, guiding optimal imaging timing.
Area of Science:
- Vascular Surgery
- Neuroradiology
- Medical Imaging
Background:
- Endovascular occlusion using Cholografin-filled silicone balloons is an option for surgically inaccessible carotid aneurysms and fistulas.
- Magnetic resonance (MR) imaging is used for noninvasive follow-up of these procedures.
Observation:
- Arterial thrombi exhibit age-related signal changes on MR, similar to intracerebral hematomas.
- Hyperacute thrombus (<24 hours) is hyperintense on T2-weighted images.
- Hemosiderin is less apparent in chronic intraluminal thrombi compared to intracerebral hematomas.
Findings:
- Cholografin-filled balloons are hypointense on T1-weighted and isointense to thrombus on T2-weighted MR images.
- Optimal MR follow-up for thrombosed aneurysms using spin-echo technique is beyond 7 days on T1-weighted images.
- The appearance of Cholografin-filled balloons remains stable on MR for up to 6 weeks.
Implications:
- MR imaging provides valuable insights into the evolution of arterial thrombi after endovascular treatment.
- Understanding MR signal characteristics aids in differentiating thrombus from residual flow and assessing treatment success.
- Established MR follow-up protocols can optimize patient monitoring and management of complex cerebrovascular lesions.
Abstract:
Three patients with surgically inaccessible giant carotid aneurysms/pseudoaneurysms and one patient with carotid cavernous fistula had endovascular occlusion with detachable silicone balloons filled with Cholografin. MR was performed before the procedures in three cases and again 18 hr to 44 days after embolization in all four cases. The age-related changes of arterial thrombi, as well as the optimal timing and value of different pulse sequences in the noninvasive follow-up, were evaluated. Arterial thrombi have some characteristics in common with intracerebral hematomas, being isointense on T1-weighted spin-echo images during acute phase and subsequently acquiring hyperintense signals on both T1- and T2-weighted spin-echo images during the subacute and chronic phases. Additional observations are that (1) hyperacute (less than 24 hr old) thrombus is hyperintense on T2-weighted spin-echo sequences; (2) hemosiderin is less conspicuous in chronic intraluminal thrombi than in intracerebral hematomas of comparable size; and (3) thrombosis is initiated at a site remote from the apex of the aneurysm and then progresses centripetally. The Cholografin-filled balloon is hypointense to gray matter on T1-weighted spin-echo images and isointense to both hyperacute and chronic thrombus on T2-weighted spin-echo images. The optimal timing and sequence for MR follow-up of a thrombosed aneurysm with conventional spin-echo technique is beyond 7 days on T1-weighted spin-echo images. The in vivo appearance of Cholografin-filled silicone balloons does not change appreciably on T1- and T2-weighted spin-echo sequences up to 6 weeks if filled according to the manufacturer's specification.