Multimodal imaging in the elastase-induced aneurysm model in rabbits: a comparative study using serial DSA, MRA and CTA.

Abstract

BACKGROUND AND PURPOSE: The elastase-induced aneurysm model in rabbits has proved to be suitable for testing new endovascular occlusion devices. The purpose of this study was to evaluate different imaging modalities for the depiction of anatomy and size of elastase-induced aneurysms and for serial follow-up imaging. MATERIALS AND METHODS: Elastase-induced aneurysms were created in eight Chinchilla bastard rabbits by endoluminal incubation of porcine elastase. Serial imaging was performed using intravenous DSA (IVDSA), contrast-enhanced MRA (CEMRA), and time-of-flight MRA (TOF) 14 days, 4 weeks and 3 months after aneurysm creation. Intraarterial DSA (IADSA) and CT angiography (CTA) were performed after 3 months. Aneurysm size and geometry (height H, width W, neck width N) were compared. RESULTS: On IVDSA after two weeks mean aneurysm height was 6.2 mm (range 2.8 - 11.0 mm), mean aneurysm width was 2.8 mm (range 2.0 - 4.2 mm) and mean aneurysm neck width was 2.7 mm (range 2.0 - 4.2 mm). We did not observed any statistically significant change in aneurysm dimensions during follow-up at 4 weeks (CEMRA: H: 5.4, W: 2.4, N: 2.4; TOF: H: 5.7, W: 2.4, N: 2.7) and 3 months (CEMRA: H: 5.8, W: 2.6, N: 2.6; TOF: H: 6.9, W: 2.8, N: 3.0). Aneurysm dimensions could be best seen on IADSA (H: 6.2, W: 3.0, N: 2.7) with good correlation to CTA (r = 0.94; H: 6.1, W: 2.8, N: 2.6), CE-MRA (r = 0.92), and TOF (r = 0.97). TOF was superior to CEMRA in delineating the aneurysm wall. CONCLUSIONS: Serial imaging using MRA, CTA or intravenous and intraarterial angiography is feasible in the elastase-induced aneurysm model. Contrast-enhanced MRA, TOF-MRA and CTA showed good correlation to IADSA and are all suitable for non-invasive pretherapeutic measurement of aneurysm size.