Detecting viable hibernating myocardium in chronic coronary artery disease- A comparison of resting Tl-201 single photon emission computed tomography (SPECT), Tc-99m-methoxy-isobutyl isonitrile SPECT after nitrate administration, and Tl-201 SPECT after Tl-201-glucose-insulin infusion

To identify and quantify the amount of viable hibernating myocardium in pat ients with chronic coronary artery disease, resting Tl-201 single photon em ission computed tomography (SPECT) was compared with Tc-99m-methoxyisobutyl isonitrile (MIBI) SPECT after nitrate infusion (nitrate-Tc-99m-MIBI) and T l-201 SPECT after Tl-201 With glucose-insulin-potassium infusion (Tl-201-GI K) in 25 patients. Twenty-one patients also underwent completely left ventr iculography beforehand and 5+/-4 months afterwards. SPECT images were divid ed into 9 segments and scored visually from 0 (normal uptake) to 3 (absent) . The defect score was calculated as the summation of the total scores (TDS ) in each patient. The TDS of nitrate-Tc-99m-MIBI images (6.3+/-4.3) and Tl -201-GIK images (5.8+/-4.2) were significantly lower than the 7.4+/-4.3 of resting Tl-201 images (p<0.01). Based on the improvement of wall motion aft er coronary revascularization, the sensitivity of Tl-201-GIK imaging (85%) was significantly higher (p<0.05), and that of nitrate-Tc-99m-MIBI imaging (79%) also tended to be higher (p=0.08), than that of Tl-201 imaging (62%) in detecting viable myocardium. The specificity of the 3 methods was almost the same. The nitrate-Tc-99m-MIBI and Tl-201-GIK methods were more useful than the resting Tl-201 method for evaluating viable hibernating myocardium . Furthermore, the Tl-201-GIK method may provide a more accurate estimate o f the amount of viable myocardium than the nitrate-Tc-99m-MIBI method.