Microvessel changes after post-ischemic benign and malignant hyperemia: experimental study in rats.
BACKGROUND
The present investigation was designed to elucidate the use of dynamic contrast enhanced perfusion MR imaging (DCE pMRI) in characterizing hyperemia, including microvessel changes, and to examine whether DCE pMRI can predict benign or malignant hyperemia.


METHODS
Sprague-Dawley rats underwent middle cerebral artery occlusion (MCAO) by intraluminal suture placement. All rats were randomized to 4 groups: MCAO for 0.5 hours followed by saline treatment (10 ml/kg; group 1); MCAO for 3 hours followed by treatment with saline (group 2) or urokinase (25000 IU/kg; group 3); and MCAO for 6 hours followed by urokinase treatment (group 4). Relative cerebral blood volume (rCBV) and relative maximum slope of increase of the signal intensity time curve (rMSI) were quantitatively analyzed from MRI. Microvessel diameter and blood-brain barrier disruption obtained by laser scanning confocal microscopy (LSCM) as well as transmission electron microscopy (TEM) were obtained for correlative study.


RESULTS
Benign hyperemia was noticed only in group 1; malignant hyperemia was seen in group 3. Although the rCBV of malignant hyperemia was slightly higher than in benign hyperemia (P > 0.05), the rMSI, on the other hand, was significantly lower (P < 0.05). Fluoro-isothiocyanate dextran (FITC-dextran) extravasations, marked glial end-foot process swelling, and significant vasodilatation were seen in malignant hyperemia, while no or mild leakage of FITC-dextran and slight glial end-foot process swelling occurred in benign hyperemia.


CONCLUSIONS
Our findings indicate that DCE pMRI can characterize post-ischemic hyperemia and correlates well with microvascular damage.
Lu
Haitao
H
Department of Diagnostic and Interventinal Radiololgy, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, 200233, PR China.
Zhao
Jungong
J
Li
Minghua
M
Cheng
Yingsheng
Y
Li
Yongdong
Y
You
Xiaofang
X
Zhao
Yuwu
Y
D000704:Analysis of Variance; D000818:Animals; D001812:Blood-Brain Barrier / Q000473:pathology / Q000648:ultrastructure; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004195:Disease Models, Animal; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006940:Hyperemia / Q000473:pathology* / Q000503:physiopathology; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D055806:Microvessels / Q000187:drug effects / Q000473:pathology* / Q000648:ultrastructure; D051381:Rats; D015424:Reperfusion / Q000379:methods; D013997:Time Factors; D014568:Urokinase-Type Plasminogen Activator / Q000627:therapeutic use
D005343:Fibrinolytic Agents; D014568:Urokinase-Type Plasminogen Activator
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