tPA-associated reperfusion after acute stroke demonstrated by SPECT

The aim of our study was twofold: to determine the frequency and magnitude of perfusion defect in stroke patients who qualify for rtPA therapy within 3 hours of stroke onset and to determine the ability of rtPA to improve perfusion by 24 hours.

Patients with suspected hemispheric stroke who fulfilled entry criteria into the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Stroke Study and also had pretreatment injection of (99m)Tc-HMPAO, with single-photon emission computed tomography (SPECT) performed using a triple-head camera at baseline and 24 hours, were included.

All 12 patients who qualified for rtPA therapy had perfusion defects on baseline SPECT (SPECT graded scale [SGS] score range, 16 to 79). Mean+/-SD perfusion defect was comparable in rtPA (n=4)versus placebo (n=5) groups (SGS score, 36+/-18 versus 39+/-12; NS) despite earlier injection time in the rtPA group (98+/-24 versus 141+/-21 minutes; P=.02). Total SPECT scanning time was 20 to 25 minutes. At 24 hours, reperfusion was greater in rtPA patients compared with the placebo group (SGS score, 7+/-9 versus 29+/-17; P=.05), with relative improvement in the region-of-interest scores of 87+/-16% after rtPA compared with 28+/-30% with placebo (P=.01).

A substantial perfusion defect exists in stroke patients with larger hemispheric infarcts who meet NINDS criteria for rtPA therapy, and rtPA is better able than placebo to rectify this defect. SPECT is feasible for clinical trials and should be evaluated as a substituted end point in stroke therapeutic trials.