Role of diffusion weighted imaging (DWI) in detection and characterization of cerebral stroke

Abstract

Background: DW MRI is a relatively recent imaging technique in which water self-diffusion is a source of contrast on MR images. 1Because cytotoxic edema occurs in just a few minutes of a critical decrease in cerebral blood flow, DWI may show most acute infarctions. This is particularly useful when thrombolytic therapy, which can only be used within a short window of opportunity, is considered. Also, DWI identifies acute lesions in patients with multiple chronic ischemic lesions. It also identifies the new extension of the previous ischemic lesions. Methodology: 50 patients with clinical signs and symptoms of stroke who underwent conventional MR imaging of brain were randomly considered for this study. These patients were prospectively subjected for DWI along with conventional MRI study. DW images were evaluated for the calculation of ADC values and ADC maps. Result: The age range of patients in this group varied from 5 years to 82 years; majority of patients being in 51 to 70 years age group. 28 patients were male and 22 were female. Of the 50 patients in this group, the MR study was performed in time interval ranging from within 6 hours after the initial symptom onset upto 4 to 7 days time interval between onset of symptoms and study. DWI imaging shows very high sensitivity compared to T2 weighted imaging particularly imaging within first 12 hours of symptoms onset. After 12 hours DWI and T2 weighted imaging show almost equal sensitivity for lesion detection.