In vivo MRI assessment of permanent middle cerebral artery occlusion by electrocoagulation: pitfalls of procedure

Abstract

Permanent middle cerebral artery (MCA) occlusion (pMCAO) by electrocoagulation is a commonly used model but with potential traumatic lesions. Early MRI monitoring may assess pMCAO for non-specific brain damage. The surgical steps of pMCAO were evaluated for traumatic cerebral injury in 22 Swiss mice using diffusion and T2-weighted MRI (7T) performed within 1 h and 24 h after surgery. Temporal muscle cauterization without MCA occlusion produced an early T2 hyperintensity mimicking an infarct. No lesion was visible after temporal muscle incision or craniotomy. Early MRI monitoring is useful to identify non-specific brain injury that could hamper neuroprotective drugs assessment.

Figure 1

MRI within one hour of surgery: T₂WI (upper row) and ADC map (lower row). A: temporal muscle cauterization alone (group A). Note the lesion with early T₂WI hyperintensity and reduced ADC (arrows). B: temporal muscle incision alone (group B). C: temporal muscle incision and craniotomy (group C). D: temporal muscle incision, craniotomy and MCA electrocoagulation. Note the ischemic lesion with low ADC (arrow) and normal T₂WI with a limited superficial traumatic lesion (arrow).

Figure 2

Impact of temporal muscle cauterization on pMCAO with T₂WI. A: temporal muscle cauterization alone (group A) showing day 0 traumatic lesion (interrupted lines). B: temporal muscle cauterization, craniotomy and MCA electrocoagulation (group E). Color-coded magnification shows the boundaries of the ischemic lesion (dotted line) and traumatic lesion (interrupted lines) 6 h after pMCAO. C: same mice at day 1 showing the limits of the final lesion (dotted line).