Effects of smoking on pulmonary uptake of technetium-99m methoxyisobutylisonitrile during myocardial perfusion imaging

Background, To determine the influence of smoking on Tc-99m-labeled methoxy isobutylisonitrile (Tc-99m-MIBI) lung uptake during myocardial perfusion im aging, we examined 60 subjects with normal myocardial perfusion scans, norm al coronary angiograms, and no evidence of left ventricular hypertrophy. Methods and Results, The subjects were divided into 2 groups: Group 1 subje cts had smoking histories of at least 10 pack-years and Group 2 subjects we re nonsmokers, 99mTc-MIBI lung to heart ratios (L/H ratios) from anterior p lanar images were obtained for all subjects during exercise and resting sta tes. Tc-99m-MIBI L/H ratios in smokers were significantly higher than in no nsmokers in both exercise and resting states, However, no significant diffe rence in L/H ratios was found between exercise and resting states in smoker s and nonsmokers. In addition, no significant correlation was found between smoking pack-years and either rest or exercise L/H ratios. Conclusions. (9)9(m)Tc-MIBI L/H ratios in smokers are higher than in nonsmo kers. This must be considered when Tc-99m-MIBI L/H ratios are used clinical ly.