Early MR detection of experimentally induced cerebral ischemia using magnetic susceptibility contrast agents: comparison between gadopentetate dimeglumine and iron oxide particles.
OBJECTIVE
To evaluate early patterns of MR changes in a rat model of cerebral ischemia using the first pass of two magnetic susceptibility contrast agents.


METHODS
One hours after endovascular middle cerebral artery occlusion, all animals were examined in an experimental MR unit. After bolus application of gadopentetate dimeglumine and, 10 minutes later, of iron oxide particles, the MR changes of the first pass of these contrast agents were followed using a T2*-weighted fast low-angle shot sequence. Time-density curves of both contrast agents were analyzed and compared.


RESULTS
After bolus injection of either (paramagnetic) gadopentetate dimeglumine or superparamagnetic particles, nonischemic brain parenchyma decreased markedly in signal, whereas the ischemic brain area remained relatively hyperintense (and thus became clearly delineated). Only after application of gadopentetate dimeglumine did a mild reduction in signal occur in the ischemic hemisphere, although the main artery was occluded. An explantation for this phenomenon might be residual capillary perfusion (plasma flow), which is detectable only when the smaller (paramagnetic) contrast molecules are being used.


CONCLUSIONS
Cerebral perfusion deficits can be detected 1 hour after vascular occlusion with T2*-weighted fast low-angle shot sequences and bolus injection of paramagnetic or superparamagnetic MR contrast agents. Gadopentetate dimeglumine may be used as a marker of microcirculatory plasma flow.
Reith
W
W
Department of Neuroradiology, University of Heidelberg Medical School, Germany.
Forsting
M
M
Vogler
H
H
Heiland
S
S
Sartor
K
K
D000818:Animals; D001810:Blood Volume / Q000502:physiology; D002545:Brain Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D002199:Capillary Permeability / Q000502:physiology; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000502:physiology; D003287:Contrast Media; D004195:Disease Models, Animal; D004338:Drug Combinations; D005290:Ferric Compounds; D005682:Gadolinium; D019786:Gadolinium DTPA; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008280:Magnetics; D008297:Male; D008536:Meglumine; D008833:Microcirculation / Q000502:physiology; D008852:Microradiography; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D051381:Rats; D017208:Rats, Wistar
D003287:Contrast Media; D004338:Drug Combinations; D005290:Ferric Compounds; D009942:Organometallic Compounds; C000499:ferric oxide; D008536:Meglumine; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA