Inconsistent MRI findings in acute pre-Willisian brain ischemia in rabbit: a useful model?

We have investigated a model of "preterminal ischemia" in order A) to assess the MRI findings and the repeatability of the anatomical changes as showed by MRI, and B) to compare the data so obtained with the humans.

Twenty rabbits were used. Under general anesthesia, the occlusion of 1) the two common carotid arteries (from 2 hours up to 24 hours) was performed in 8 cases, and of 2) the epi-aortic vessels at the aortic arch (from 2 hours up to 4 hours) was performed in 4 cases in general anesthesia.

In the vessels occlusion group MRI study showed inconsistent, inconstant, predominantly ill defined, linear and/or spotlike hyperintense deep cerebral alterations, variable in location, unilateral and bilateral in 8 cases. Although in carotid occlusion the damage was already evident within the first two hours, aortic arch occlusion was unable to produce global brain lesional pattern even up to 4 hours. MRI study of the sham operated animals was negative.

The selective vulnerability of mesial deep cerebral structures to hypoxia, different in location from the human's, and the more effective pre-Willisian compensation, suggests to look for different animals when dealing with preterminal ischemic models comparable to the humans' as studied with MRI.