Complications and pitfalls in rat stroke models for middle cerebral artery occlusion -: A comparison between the suture and the macrosphere model using magnetic resonance angiography

Background and Purpose-Investigating focal cerebral ischemia requires animal models that are relevant to human stroke. Complications and side effects are common among these models. The present study describes potential pitfalls in 3 techniques for middle cerebral artery occlusion (MCAO) in rats using magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). Methods-Rats were subjected to temporary MCAO for 90 minutes using the suture technique (group I; n = 10) or to permanent MCAO using the suture technique (group II; n = 10) or the macrosphere technique (group III; n = 10). Clinical evaluation was performed after 3 hours and 24 hours. After 24 hours, animals underwent MRI and MRA to determine lesion size and the intracranial vascular status. Results-Hemispheric lesion volume was significantly smaller in group I (14.6%) compared with groups II (35.2%; P<0.01) and III (21.3%; P<0.05). Two animals (1 each in group II and III) did not demonstrate neurological deficits and had no lesion on MRI and a patent MCA main stem on MRA. Subarachnoid hemorrhage was detected in 2 animals ( 1 each in group I and II). MRA indicated a patent MCA main stem in 2 animals ( group II), although both rats displayed neurological deficits. Hypothalamic infarction with subsequent pathological hyperthermia was detected in all animals in group II and in 1 rat in group III. Conclusions-Model failures occurred frequently in all groups. MRI and MRA helps to identify animals that need to be excluded from experimental stroke studies.