PULMONARY UPTAKE OF TECHNETIUM-99M-SESTAMIBI INDUCED BY DIPYRIDAMOLE-BASED STRESS OR EXERCISE

On poststress images with Tc-99m-sestamibi (MIBI), increased lung upta ke of the radiotracer may reflect severe or multivessel coronary arter y disease. Methods: We measured pulmonary/myocardial ratios of MIBI at standardized times on immediate poststress acquisitions and on delaye d tomographic acquisitions, In 1500 sequential patients referred for r est and stress myocardial tomography, ancillary planar images were obt ained 4 min postinjection at peak stress with exercise, either alone ( exercise, n = 674), or after intravenous dipyridamole (dipyridamole, n = 826). Results: Based on 95% confidence limits in the angiographic n ormals, high values for immediate acquisitions were found in 17% of di pyridamole studies and 15% of exercise studies. High values for delaye d acquisitions were found in 10% of dipyridamole studies and 9% of exe rcise studies. For both stress modes, increased values were related (p < 0.001) to ischemic perfusion defects for immediate images, to fixed defects for delayed images, and to ventricular dilation in both cases . By logistic regression analysis, body weight and history of infarcti on were also minor independent determinants (p < 0.01) of delayed acqu isitions. In a subset of 250 cases with angiographic correlation (163 with dipyridamole; 87 with exercise), immediate lung uptake was highly correlated with ventricular dysfunction and with coronary stenoses (p < 0.0001). Relationships were similar to those in a historic control series imaged with (TI)-T-201. Values for delayed poststress images, a nd for corresponding rest images, showed strong relationships to ventr icular dysfunction but not to stenosis severity. Conclusion: The relat ionships of immediate lung uptake to scintigraphic and angiographic di sease patterns suggest its possible diagnostic use as an indicator of stress-induced ventricular decompensation.