Temporal changes in diffusion coefficients after stroke.

Purpose: Analysis of temporal changes of ADC-values at different stages aft er stroke. Materials and Methods: The original images of all scans were eva luated and a region of interest analysis was performed on ADC (apparent dif fusion coefficient) maps. 92 patients with symptoms of ischemic stroke were examined at 1.5 Tesla (ACS-NT, Philips Medical Systems). The study protoco l included a navigated multishot SE-EPI DWI (b = 0, 189, 750 s/mm(-2), T-E = 120/140 ms, delta/Delta = 49/60 ms), a GraSE (T-R/T-E = 3500/90 ms) and a FLAIR-TSE (T-R/T-E/T-I = 6000/150/2000 ms) sequence. 8 patients had regula r follow-ups. All patients had an additional CT scan. Results: In hyperacut e stroke (< 6 h, n = 10) the relative ADC of the infarct core dropped to ab out 50% and reached a minimum in the acute state (6 - 48 h, n = 14) during the next few hours. In subacute stroke (< 3 weeks, n = 29) the ADC began to rise significantly (p = 0.001) back to normal values and reached (p < 10(- 4)) values similar to cerebrospinal fluid in the chronic state (> 3 weeks, n = 20). The combined use of DWI and conventional MRI improved the diagnost ic information in 16% of all MR examination beyond the hyperacute assessmen t. Conclusion: By means of the ADC-values the age of stroke can be determin ed. Infarcts at different stages can be readily diagnosed with the combined use of DWI, FLAIR-TSE and GraSE. Pitfalls of DWI and conventional imaging can be avoided.