The Value of DWI in the Diagnosis of Cerebral Infarction and Ischemia

This is to report the value of diffusion-weighted images (DWI) in the diagnosis of cerebral infarction and ischemia. Thirty patients with brain ischemia or infarction underwent diffusion-weighted EPI SE (TR/TE= 4700/118 ms) study at a 1.5 T MRI (Vision, Siemens, Erlangen, Germany). The DWI was performed in three axes with b value equals to 1000 s/mm ². MRI of these cases all had routine brain studies including axial T1 SE (TR/TE= 550ms/14ms) and T2 TSE (TR/TE = 3000ms/20ms, 90ms) for comparison. In twenty seven patients whose MR examinations were performed 3 hours to 14 days after acute onset of clinical symptoms had consistent high signal change in the same area on the three DWI with different diffusion gradient direction. In two patients, the DWI was the only positive examination and the conventional MRI performed at the same time showed no abnormal change. They were done three hours after onset of clinical symptoms. Only DWI can tell the acute or subacute nature of infarct, while conventional MRI can not tell in eight patients. They were done more than 24 hours after onset of clinical symptoms. These eight cases were: two cortical lacunar infarcts, one periventricular lacunar infarct, two located adjacent to old infarct, three adjacent to periventricular arteriosclerotic angiopathic leukoencephalopathy. Another three patients only had old infarct where low signal was found in the DWI. DWI is sensitive for detection of brain ischemia, acute and subacute infarction. It can be shown well even if the lesion is in the periventricular or in cortical sulci adjacent to CSF spaces. DWI can be used to differentiate brain ischemia, acute (or subacule) infarct from old infarct and arteriosclerotic angiopathic leukoencephalopathy. DWI will become routine procedure in the diagnosis of brain ischemia and acute (or subacute) infarct.