Potential of early [(18)F]-2-fluoro-2-deoxy-D-glucose positron emission tomography for identifying hypoperfusion and predicting fate of tissue in a rat embolic stroke model.
OBJECTIVE
Experimental stroke models are essential to study in vivo pathophysiological processes of focal cerebral ischemia. In this study, an embolic stroke model in rats was applied (1) to characterize early development of regional cerebral blood flow and metabolism with positron emission tomography (PET) using [(15)O]H(2)O and [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG); and (2) to identify potential parameters for predicting tissue fate.


METHODS
Remote occlusion of the middle cerebral artery was induced in 10 Wistar rats by injection of 4 TiO(2) macrospheres. Sequential [(15)O]H(2)O-PET (baseline, 5, 30, 60 minutes after middle cerebral artery occlusion) and FDG-PET measurements (75 minutes after middle cerebral artery occlusion) were performed. [(15)O]H(2)O-PET data and FDG kinetic parameters were compared with MRIs and histology at 24 hours.


RESULTS
Regional cerebral blood flow decreased substantially within 30 minutes after middle cerebral artery occlusion (41% to 58% of baseline regional cerebral blood flow; P<0.001) with no relevant changes between 30 and 60 minutes. At 60 minutes, regional cerebral blood flow correlated well with the unidirectional transport parameter K1 of FDG in all animals (r=0.86±0.09; P<0.001). Tissue fate could be accurately predicted taking into account K1 and net influx rate constant Ki of FDG. The infarct volume predicted by FDG-PET (375.8±102.3 mm(3)) correlated significantly with the infarct size determined by MRI after 24 hours (360.8±93.7 mm(3); r=0.85).


CONCLUSIONS
Hypoperfused tissue can be identified by decreased K1 of FDG. Acute ischemic tissue can be well characterized using K1 and Ki allowing for discrimination between infarct core and early viable tissue. Because FDG-PET is widely spread, our findings can be easily translated into clinical application for early diagnoses of ischemia.
Department of Neurology, University Hospital, Cologne, Germany.
Maureen
M
Walberer
Heiko
H
Backes
Maria A
MA
Rueger
Bernd
B
Neumaier
Heike
H
Endepols
Mathias
M
Hoehn
Gereon R
GR
Fink
Michael
M
Schroeter
Rudolf
R
Graf
D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging; D002545:Brain Ischemia / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation / Q000502:physiology; D004195:Disease Models, Animal; D019788:Fluorodeoxyglucose F18; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D051381:Rats; D017208:Rats, Wistar
D019788:Fluorodeoxyglucose F18