Tl-201 Liver Uptake For Assessment Of Jeopardized Myocardium During Dipyridamole Stress-Testing

The current study was conducted to determine the significance of Tl-201 liver activity during 4 minute dipyridamole (DP) stress testing. Two groups of subjects were examined: group I subjects (n = 52) had electrocardiographic evidence of left ventricular hypertrophy (ECG-LVH), and group 11 subjects (n = 114) had no ECG-LVH. Both groups were further divided into four subgroups on the basis of Tl-201 myocardial perfusion scans: 1) no myocardial perfusion defect; 2) transient myocardial perfusion defect; 3) fixed myocardial perfusion defect; and 4) transient plus fixed myocardial perfusion defects. Tl-201 liver, heart, and lung activities were quantified in the immediate anterior planar images. Left ventricular mass was quantified using tomographic short-axis slices. In the no ECG-LVH group, Tl-201 lung-to-heart ratio was significantly increased in subjects having transient, fixed, and transient plus fixed myocardial perfusion defects when compared to no myocardial perfusion defect. Tl-201 lung-to-heart ratio did not increase in the ECG-LVH group of subjects having transient, fixed, and transient plus fixed myocardial perfusion defects. In contrast, Tl-201 liver-to-heart ratio increased in both the ECG-LVH and no ECG-LVH groups of subjects having myocardial perfusion defects when compared to subjects having negative myocardial perfusion scan. Left ventricular mass was increased in ECG-LVH subjects when compared to no ECG-LVH subjects, which might have resulted in increased Tl-201 myocardial uptake and, hence, reduced Tl-201 lung-to-heart ratio in ECG-LVH subjects having myocardial perfusion defects. The authors conclude that Tl-201 liver-to-heart ratio, but not Tl-201 lung-to-heart ratio, provided supplementary information regarding the ''jeopardized'' myocardium in ECG-LVH subjects during DP stress testing.