Serial diffusion tensor MRI after transient and permanent cerebral ischemia in nonhuman primates.
OBJECTIVE
We measured the temporal evolution of the T2 and diffusion tensor imaging parameters after transient and permanent cerebral middle cerebral artery occlusion (MCAo) in macaques, and compared it to standard histological analysis at the study end point.


METHODS
Stroke was created in adult male macaques by occluding a middle cerebral artery branch for 3 hours (transient MCAo, n=4 or permanent occlusion, n=3). Conventional MRI and diffusion tensor imaging scans were performed 0 (acute day), 1, 3, 7, 10, 17, and 30 days after MCAo. Animals were euthanized after the final scan and the brains removed for histological analysis.


RESULTS
Apparent diffusion coefficient in the lesion was decreased acutely, fractional anisotropy was elevated, and T2 remained normal. Thereafter, apparent diffusion coefficient increased above normal, fractional anisotropy decreased to below normal, T2 increased to a maximum and then declined. Reperfusion at 3 hours accelerated these MRI changes. Only the fractional anisotropy value was significantly different between transient and permanent groups at 30 days. Final MRI-defined fractional lesion volumes were well correlated with corresponding histological lesion volumes. Permanent MCAO animals showed more severe histological damage than their transient MCAO counterparts, especially myelin damage and axonal swelling.


CONCLUSIONS
Overall, the MRI evolution of stroke in macaques was closer to what has been observed in humans than in rodent models. This work supports the use of serial MRI in stroke studies in nonhuman primates.
Liu
Yutong
Y
Martinos Center, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129-2060, USA.
D'Arceuil
Helen E
HE
Westmoreland
Susan
S
He
Julian
J
Duggan
Michael
M
Gonzalez
R Gilberto
RG
Pryor
Johnny
J
de Crespigny
Alex J
AJ
D000818:Animals; D016880:Anisotropy; D002545:Brain Ischemia / Q000473:pathology* / Q000503:physiopathology; D002536:Cerebral Arteries / Q000473:pathology / Q000503:physiopathology; D002540:Cerebral Cortex / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D002544:Cerebral Infarction / Q000473:pathology* / Q000503:physiopathology; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004195:Disease Models, Animal; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology / Q000503:physiopathology; D008252:Macaca fascicularis; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology