Diffusion weighted imaging in acute stroke and stroke mimics: reliability analysis, radiological findings and clinical significance

Background: To assess the reliability and to determine the sensitivity and specificity of Diffusion Weighted Images (DWI) in detection of acute infarcts in patients whose initial CT and conventional MR-sequences did not explain the patients stroke symptoms. The second aim was to find out if DWI provides additional information when it was performed within 2 days of onset of symptoms. Patients and methods: MRI and DWI of 59 consecutive patients [66 % were male; aged 60 ± 14 year (Mean ± SD)] admitted with stroke and stroke like episodes were retrospectively analyzed. The images were independently evaluated by two neuroradiologists. Results: DWI showed acute infarct in 25 patients (42 %). Hemiplegia and dizziness were the most common symptoms in patients with positive and negative DWI, respectively. Lacunar infarcts near the motor cortex were the most common type of infarcts detected by DWI. DWI provided additional information in 89 % of patients when performed within 2 days of ictus compared 31 % in patients examined ≥2 days after ictus (Fisher ́s exact test, P 0.011). DWI provided relevant information in 26 % of patients despite negative DWI. The specificity and sensitivity of DWI in acute stroke was 100 % and 89 % respectively. Conclusion: DWI is a reliable MRsequence in the workup of acute and subacute stroke. DWI helps to differentiate acute infarcts from other white matter changes seen on conventional MRI-sequences. In patients with stroke like episodes, a negative DWI provides relevant clinical information and help in future clinical management.