Prospective Value of Perfusion and X-Ray Attenuation Imaging With Single-Photon Emission and Transmission Computed Tomography in Acute Cerebral Ischemia

Abstract

Background and Purpose —The aim of the present study was to test the hypothesis that perfusion single-photon emission computed tomography (SPECT), carried out in addition to transmission computed tomography (TCT), improves the predictive value of brain imaging within the therapeutically relevant time window after acute cerebral ischemia. Methods —Using TCT and [ 99m Tc]ethyl cysteinate dimer (ECD)-SPECT within 6 hours after symptom onset, we examined 108 patients (44 women, 64 men; mean age 65±13 years) with acute ischemic stroke attributed to the territory of the middle cerebral artery (MCA). In each case, 3 experts prospectively evaluated the early SPECT and TCT images. We correlated these ratings with follow-up TCT findings for the final infarction as well as with clinical outcome (Scandinavian Stroke Scale, Barthel Index, Modified Rankin Scale) after 30 and 90 days. Results —Severe activity deficits on SPECT, not caused by local atrophy on TCT, were the best predictors (positive predictive value [PPV ]94%, 95% CI 89% to 99%; negative predictive value [NPV] 90%, 95% CI 78% to 100%; P <0.001) for evolving cerebral infarction. Complete MCA infarctions were predicted with significantly higher accuracy with early SPECT (area under receiver operating characteristic curve [AUC] index 0.91) compared with early TCT (AUC index 0.77) and clinical parameters (AUC index 0.73, P <0.05). Logistic regression analysis revealed 1 independent predictor for completed MCA territory infarction: SPECT activity deficits in the corresponding areas (PPV 88%, 95% CI 65% to 100%; NPV 96%, 95% CI 92% to 100%; P <0.001). Furthermore, death after stroke was optimally predicted by [ 99m Tc]ECD-SPECT. Clinical outcome up to 90 days after the stroke event best correlated with the degree of activity deficits in early SPECT ( r =0.53, P <0.001). Conclusions —[ 99m Tc]ECD brain perfusion SPECT that completes TCT definitely improves the predictive value of brain imaging after acute cerebral ischemia. Thus, the combined imaging of brain edema and of cerebral perfusion early after stroke is recommended for clinical use.