Identification of major ischemic change - Diffusion-weighted imaging versus computed tomography

Background and Purpose-Thrombolytic therapy is not recommended in patients with CT changes of recent major infarction, which has been defined as reduc ed attenuation or cerebral edema involving >33% of the middle cerebral arte ry territory (European Cooperative Acute Stroke Study [ECASS] criteria).Dif fusion-weighted imaging (DWI) is more sensitive than CT in detecting acute ischemia, and the combination of DWI, MR perfusion imaging, and MR angiogra phy provides additional information from a single examination. We sought to determine whether DWI could identify the presence and extent of major isch emia as we:ll as CT in hyperacute stroke patients. Methods-Seventeen suspected hemispheric stroke patients were studied with b oth CT and DWI within 6 hours of symptom onset. None received thrombolytic therapy. The scans were examined separately by 2 neuroradiologists in a bli nded fashion for ischemic change and cerebral edema, graded as normal, <33% , or >33% of the MCA territory. Final diagnosis of stroke was determined wi th the use of standard clinical criteria and T2-weighted imaging at day 90, Results-Sixteen of 17 patients had a final diagnosis of stroke. Acute ische mic changes were seen in all 16 on DWI (100% sensitivity) and in 12 of 16 o n CT (75% sensitivity). DWI identified all 6 patients with major ischemia o n CT, with excellent agreement between the 2 imaging techniques (kappa=0.88 ). One patient eligible for thrombolysis on the ECASS CT criteria had major ischemia on DWI. Conclusions-DWI is more sensitive than CT in the identification of acute is chemia and can visualize major ischemia more easily than CT.