Comparison of Glucose-Insulin-Thallium-201 Infusion Single Photon Emission Computed Tomography(SPECT), Stress-Redistribution-Reinjection Thallium-201 SPECT and Low Dose Dobutamine Echocardiography for Prediction of Reversible Dysfunction

The usefulness of glucose-insulin-thallium-201(GI-Tl)infusion single photon emission computed tomography(SPECT)in predicting reversible dysfunction has not been evaluated, so the present study recruited 20 patients with regional ischemic dysfunction for investigation. All patients underwent GI-Tl SPECT, post-stress Tl reinjection imaging and low dose dobutamine echocardiography. The diagnostic accuracy of these 3 techniques in piedicting functional recovery was evaluated by receiver operating characteristic(ROC)analysis. In segments with functional recovery, regional Tl activities of GI-Tl SPECT were significantly higher than those of reinjection imaging(p<0.05), although there were no significant differences in segments without recovery. The area under the ROC curve for GI-Tl SPECT(0.75±0.06)was greater than that for reinjection imaging(0.68±0.07). The optimal cutoff values to identify viable myocardium were considered to be 55% of peak activity for GI-Tl SPECT and 50% for reinjection imaging. At this cutoff point, the sensitivity and specificity for detection of functional recovery were, respectively, 85% and 61% for GI-Tl SPECT, and 73% and 61% for reinjection imaging. Dobutamine echocardiography had the same sensitivity(85%), but lower specificity(48%)than GI-Tl SPECT. Continuous infusion of GI-Tl solution enhances regional Tl uptake compared with conventional post-stress reinjection imaging. This study suggests that GI-Tl SPECT is superior to reinjection imaging and dobutamine echocardiography in predicting functional recovery after ischemic left ventricular dysfunction.