Time course of the apparent diffusion coefficient after XXXX .

@entity1 @entity2806 @entity63 @entity1188 @entity385
The purpose of this study was to evaluate quantitative apparent diffusion changes in the center of @entity1188 by measurement of the apparent diffusion coefficient (ADC), and to investigate the influence of @entity63 on the contralateral hemisphere. By diffusion echo-planar imaging (EPI) 52 @entity1 showing @entity385 were studied within 5 h to >12 months after onset of clinical symptoms. Using three diffusion gradient strengths (b1=30 s/mm(2); b2=300 s/mm(2), b3=1100 s/mm(2)) ADC maps were generated. After onset of @entity63 , ADC in the center of @entity1188 was lower than in the contralateral regions of @entity1 brain. At first ADC declined for approximately 28 h to a minimum of approximately 150x10(-8) cm(2)/s. Then the ADC reincreased and reached a "pseudonormalization" after approximately 5 days. @entity1188 did show much higher ADC values (2000x10(-8) cm(2)/s) than unaffected areas. Neither localization nor size of @entity1188 showed a significant influence on this time course. In the center of @entity1188 diffusion is isotropic. Even brain regions of the contralateral hemisphere are influenced by @entity2806 . In these regions ADC is higher than for physiological conditions. The ADC also declines especially for the first 2-3 days after onset of symptoms, also followed by reincrease. The ADC calculation enables determination of the onset of @entity1188 more exactly than is possible using only diffusion-weighted imaging. Diffusion in the center of @entity1188 is isotropic; hence, orientation of the diffusion gradients has no significant influence on sensitivity of measurements. The calculation of the ADC ratio based on data derived from the center of @entity1188 and the contralateral hemisphere seems to be critical because the ADC in the unaffected contralateral hemisphere also changes.
