LUNG UPTAKE OF TL-201 - A MARKER OF DEFECT REVERSIBILITY

High lung uptake of thallium-201 at stress is reported to be associate d with a large number of perfusion defects and poor prognosis. This st udy was performed to assess whether the reversibility of stress perfus ion defects was related to lung uptake. Gated planar thallium scans at stress and at redistribution from 102 consecutive patients with essen tially normal left ventricular ejection fraction (using Tc-99m gated b lood pool ventriculography) were graded in terms of defect size. Lung and myocardial uptake of thallium were quantitated by region of intere st methods relative to the given activity in a previously validated me thod. There was no significant correlation (non-parametric) between lu ng uptake and degree of redistribution (p = ns, r(s) = 0.140). There w as a weak but positive correlation between lung uptake and defect size (p < 0.05, r(s) = 0.188). Both exercise time and double product showe d a negative correlation with lung uptake (e.g. for double product, p < 0.0005, r(s) = -0.541). In conclusion, contrary to our expectation, lung uptake is not related to the degree of redistribution. High lung uptake seems to reflect poor cardiovascular reserve.