Prediction of tissue survival after middle cerebral artery occlusion based on changes in the apparent diffusion of water.
OBJECTIVE
In this study the authors tested the hypothesis that the estimate of the apparent diffusion coefficient (ADC) of water is a reliable pathophysiological index of the viability of ischemic brain tissue.


METHODS
Cerebral blood flow (CBF) and the cerebral metabolic rates of oxygen and glucose (CMRO2 and CMRglc, respectively) were measured using positron emission tomography (PET) scanning before and after permanent middle cerebral artery occlusion (MCAO) or reperfusion in pigs. The ADC value, which was measured using diffusion-weighted magnetic resonance (DW MR) imaging was compared with physiological variables obtained by PET scanning and with histological findings. After both permanent MCAO and reperfusion, the decrease in the ADC was significantly correlated with decrease in the CMRO2 and CMRglc. The infarction coincided with a CMRO2 threshold of 50% of the value measured on the contralateral side. Thus, an ADC value of 80% or 75% of the contralateral value reflected the CMRO2 threshold after permanent MCAO or reperfusion, respectively. On DW MR images, lesions with ADC values above 80% of the contralateral value are potentially reversible until 6 hours after MCAO, whereas lesions with ADC values below 75% of the contralateral value are irreversible as early as 2 hours after MCAO.


CONCLUSIONS
The ADC of water provides a reliable pathophysiological index for tailoring therapy to the condition of individual stroke patients in clinical practice.
Sakoh
M
M
Positron Emission Tomography Center, Department of Neuroradiology and Biological Psychiatry, Aarhus University Hospital, Denmark. sakoh@m.ehime-u.ac.jp
Ostergaard
L
L
Gjedde
A
A
Røhl
L
L
Vestergaard-Poulsen
P
P
Smith
D F
DF
Le Bihan
D
D
Sakaki
S
S
Gyldensted
C
C
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging; D004058:Diffusion; D004292:Dominance, Cerebral / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D007089:Image Enhancement; D020244:Infarction, Middle Cerebral Artery / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D010101:Oxygen Consumption / Q000502:physiology; D012039:Regional Blood Flow; D015427:Reperfusion Injury / Q000503:physiopathology; D013552:Swine; D014022:Tissue Survival / Q000502:physiology*; D014055:Tomography, Emission-Computed
D001786:Blood Glucose