MRI of spontaneous fluctuations after acute cerebral ischemia in nonhuman primates.
OBJECTIVE
To study the spontaneous low-frequency blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signal fluctuations during hyperacute focal cerebral ischemia.


METHODS
A stroke model in nonhuman primates (macaques) was used in this study. Spontaneous fluctuations were recorded using a series of gradient-recalled echo (GRE) echo-planar imaging (EPI) images. Fast Fourier transformation (FFT) was performed on the serial EPI data to calculate the frequency and magnitude of the spontaneous fluctuations. Diffusion tensor imaging (DTI) and perfusion-weighted imaging (PWI) were preformed to detect the ischemic lesion.


RESULTS
The frequency of these fluctuations decreased in the periinfarct tissue in the ipsilateral hemisphere, while their magnitude increased. This area of abnormal signal fluctuations often extended beyond the hyperacute diffusion/perfusion abnormality.


CONCLUSIONS
This study suggests that measurement of the spontaneous fMRI signal fluctuations provides different information than is available from diffusion/perfusion or T2-weighted MRI.
Liu
Yutong
Y
Martinos Center, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts.
D'Arceuil
Helen
H
He
Julian
J
Duggan
Mike
M
Gonzalez
Gilberto
G
Pryor
Johnny
J
de Crespigny
Alex
A
D000208:Acute Disease; D000818:Animals; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000175:diagnosis* / Q000473:pathology*; D004058:Diffusion; D017352:Echo-Planar Imaging / Q000379:methods; D005583:Fourier Analysis; D007511:Ischemia / Q000473:pathology; D008251:Macaca; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010477:Perfusion; D011323:Primates; D015203:Reproducibility of Results; D013997:Time Factors