TY - JOUR T1 - Evolution of Apparent Diffusion Coefficient, Diffusion-weighted, and T2-weighted Signal Intensity of Acute Stroke JF - American Journal of Neuroradiology JO - Am. J. Neuroradiol. SP - 637 LP - 644 VL - 22 IS - 4 AU - Maarten G. Lansberg AU - Vincent N. Thijs AU - Michael W. O'Brien AU - Juan O. Ali AU - Alex J. de Crespigny AU - David C. Tong AU - Michael E. Moseley AU - Gregory W. Albers Y1 - 2001/04/01 UR - http://www.ajnr.org/content/22/4/637.abstract N2 - BACKGROUND AND PURPOSE: Serial study of such MR parameters as diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC), ADC with fluid-attenuated inversion recovery (ADCFLAIR), and T2-weighted imaging may provide information on the pathophysiological mechanisms of acute ischemic stroke. Our goals were to establish the natural evolution of MR signal intensity characteristics of acute ischemic lesions and to assess the potential of using specific MR parameters to estimate lesion age.METHODS: Five serial echo-planar DWI studies with and without an inversion recovery pulse were performed in 27 patients with acute stroke. The following lesion characteristics were studied: 1) conventional ADC (ADCCONV); 2) ADCFLAIR; 3) DWI signal intensity (SIDWI); 4) T2-weighted signal intensity (SIT2), and 5) FLAIR signal intensity (SIFLAIR).RESULTS: The lesion ADCCONV gradually increased from low values during the first week to pseudonormal during the second week to supranormal thereafter. The lesion ADCFLAIR showed the same pattern of evolution but with lower absolute values. A low ADC value indicated, with good sensitivity (88%) and specificity (90%), that a lesion was less than 10 days old. All signal intensities remained high throughout follow-up. SIDWI showed no significant change during the first week but decreased thereafter. SIT2 initially increased, decreased slightly during week 2, and again increased after 14 days. SIFLAIR showed the same initial increase as the SIT2 but remained relatively stable thereafter.CONCLUSION: Our findings further clarify the time course of stroke evolution on MR parameters and indicate that the ADC map may be useful for estimating lesion age. Application of an inversion recovery pulse results in lower, potentially more accurate, absolute ADC values. ER -