Hyperactivity of 99mTc-HMPAO within 6 hours in patients with acute ischemic stroke.

UNLABELLED Intraarterial thrombolytic therapy has been used recently for treatment of acute ischemic stroke within 6 h after onset. Although hypoactivity of 99mTc-hexamethylpropyleneamine oxime (HMPAO) in stroke has been well documented, hyperactivity of HMPAO has not been evaluated in sufficient detail. The purpose of this study was to evaluate the incidence and clinical importance of hyperactivity of HMPAO in management of patients with acute ischemic stroke. METHODS We retrospectively investigated HMPAO SPECT in 90 patients with acute ischemic stroke within 6 h after onset. The lesion-to-contralateral radioactivity ratios (L/Cs) were calculated on the SPECT images before treatment and were compared with the imaging results of CT or MRI (or both). RESULTS Hyperactivity of HMPAO, accompanied by surrounding hypoactivity, was observed in 6 of 90 patients (7%) within 6 h after onset. The L/Cs ranged from 1.17 to 2.95. Two patients showed hyperactivity in the cortex and the other 4 patients showed hyperactivity in the basal ganglia. Angiography confirmed spontaneous recanalization of occluded vessels in accordance with the area of hyperactivity. In both patients with cortical hyperactivity, cerebral infarctions were revealed on follow-up CT; in 1 patient, hemorrhagic transformation developed after intraarterial thrombolytic therapy. In 3 of the 4 patients with hyperactivity in the basal ganglia, follow-up CT showed no infarction in the surrounding hypoperfused cortex (selective intraarterial thrombolytic therapy was performed on 2 patients), although various degrees of infarction were observed in the basal ganglia. Obvious infarctions developed in the basal ganglia and the cortex of the other patient. CONCLUSION Hyperactivity of HMPAO could be seen in the basal ganglia and the cortex within 6 h after onset, reflecting spontaneous recanalization. The areas of hyperactivity may develop infarctions, whereas the accompanying areas of hypoactivity could be rescued by selective intraarterial thrombolytic therapy.