Diffusion-weighted imaging of patients with subacute cerebral ischemia: Comparison with conventional and contrast-enhanced MR imaging

BACKGROUND AND PURPOSE: The importance of diffusion-weighted imaging (DWI) for delineating acute ischemic lesions has been investigated extensively; h owever, few studies have investigated the role of DWI in the subacute stage of stroke. Because these lesions tend to appear bright throughout the firs t days of ischemia, owing to restricted diffusion, we speculated that DWI c ould also improve the detection of subacute infarcts as compared with conve ntional and contrast-enhanced MR imaging. METHODS: Interleaved echo-planar DWI with phase navigation was performed on a 1,5-T MR unit in a consecutive series of 53 patients (mean age, 66 +/- 1 4 years) with suspected recent cerebral ischemia, The interval between onse t of clinical symptoms and MR imaging ranged from 1 to 14 days (mean, 6 +/- 4 days). Contrast material was given to 28 patients in a dose of 0.1 mmol/ kg, RESULTS: DWI clearly delineated recent ischemic damage in 39 patients (74%) as compared with 33 (62%) in whom lesions were identified or suspected on conventional T2-weighted images. DWI provided information not accessible wi th T2-weighted imaging in 17 patients when evidence of lesion multiplicity or detection of clinically unrelated recent lesions was included for compar ison. Subacute ischemic lesions mere also seen more frequently on DWI seque nces than on contrast-enhanced images (20 versus 13 patients). DWI was more likely to make a diagnostic contribution in the first meek of stroke and i n patients with small lesions or preexisting ischemic cerebral damage than was conventional MR imaging. CONCLUSION: Recent ischemic damage is better shown on DWI sequences than on conventional and contrast-enhanced MR images throughout the first days aft er stroke and may provide further information about the origin of clinical symptoms. Adding DWI to imaging protocols for patients with subacute cerebr al ischemia is recommended.