Recovery of apparent diffusion coefficient after embolic stroke does not signify complete salvage of post-ischemic neuronal tissue.
OBJECTIVE
It has been shown in previous studies that recovery of apparent diffusion coefficient (ADC) of water is not necessarily associated with a reversal of tissue damage. We examined the relationships between temporal ADC change and histological outcome after embolic stroke in rat using an experimental MRI scanner.


METHODS
Male Wistar rats underwent embolization of the right middle cerebral artery with autologous clot. ADC and relative cerebral blood flow (rCBF) were measured consecutively for 3 hours after embolization. The brains were prepared for histological examination.


RESULTS
Transient decline of ADC was observed during the initial 2 hours after embolization. In these areas, serial rCBF measurement revealed incomplete recovery. In some other areas, ADC decrease without rCBF recovery was observed during 3 hours postischemia. Histological examination revealed infarction in areas with persistent ADC decrease. Scattered neuronal death was noticeable in areas with a transient--in some areas less than 0.5 hour--ADC decrease.


CONCLUSIONS
Consecutive MRI analysis demonstrated postischemic transient ADC decrease in an embolic stroke model of rat. The normalization of ADC does not signify normalization of postischemic tissue, since the areas often evolve postischemic neuronal death at a later time.
Tanaka
Y
Y
Department of Neurosurgery, Tokyo Medical and Dental University, Tokyo, Japan. tanaka.nsrg@tmd.ac.jp
Kuroiwa
T
T
Miyasaka
N
N
Tanabe
F
F
Nagaoka
T
T
Ohno
K
K
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D016923:Cell Death; D002544:Cerebral Infarction / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D020766:Intracranial Embolism / Q000150:complications*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D020127:Recovery of Function; D020521:Stroke / Q000175:diagnosis / Q000209:etiology* / Q000378:metabolism* / Q000473:pathology; D013997:Time Factors