[Usefulness of diffusion-weighted MRI in the diagnosis of transient ischemic attacks]

Diffusion-weighted imaging(DWI) has been demonstrated to be valuable for assessment of ischemic stroke patients. The aim of this study is to evaluate clinical usefulness of DWI in the diagnosis of transient ischemic attack(TIA). Nineteen patients with symptoms of TIA were studied. DWI was taken with 1.5 Tesla MRI system using spin echo EPI sequence. Seven patients revealed areas of hyperintensity (brightness) on DWI and of hypointensity on apparent diffusion coefficient(ADC) maps relative to normal brain. As the duration of TIA symptom elongated, the percentage of patients with DWI abnormalities became higher. DWI enabled to detect areas of hyperintense lesion in all three patients as early as 3 hours after the onset, while conventional T2 weighted imaging showed in one. All the DWI abnormalities were irreversible in spite of the complete recovery from TIA. DWI is an useful technique for the detection of responsible lesions in TIA. However, TIA cannot be ruled out even if DWI does not demonstrate any abnormal signals.