We evaluated regional apparent diffusion coefficient (ADC) change of the brain during the cardiac cycle (ΔADC) . On a 1.5-T MRI, ECG-triggered single-shot diffusion echo planar imaging was used with sensitivity encoding, half scan and rectangular FOV techniques to minimize the bulk motion such as brain pulsation, i.e., data-sampling window of 3ms. ΔADC image was calculated from maximum minus minimum ADC value of all cardiac phase images on a pixel-by-pixel basis. We determined ΔADC in regions of parietal, frontal, temporal and occipital white matters (WM) in twelve healthy volunteers. Moreover, we assessed influences of scan parameters on ΔADC. ΔADC was affected by b-values, but unaffected by voxel size. There was no significant correlation between ΔADC and ADC. The ΔADC values in parietal WM at centrum semiovale level were significantly higher than those in temporal WM at basal ganglia level, although there was no significant difference in ADC values between among WM regions. ΔADC analysis using appropriate scan parameter makes it possible to noninvasively obtain new and more detailed information on the regional brain condition.
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