[Quantitative evaluation of pulmonary perfusion volume using 99mTc-MAA SPECT: a comparison of COPD patients and healthy volunteers].

99mTc-MAA pulmonary perfusion single-photon emission computed tomography was performed on 18 patients with chronic obstructive pulmonary disease (COPD) and 41 healthy male volunteers. We quantified the extent of pulmonary perfusion with the Application Visualization System. We measured the pulmonary perfusion volume (PV) at 8 threshold levels encompassing 10 percentage points each from 21-100%. We also calculated the ratio of perfusion volume to total perfusion volume (TPV) at each threshold. Pulmonary perfusion volume in healthy volunteers remained relatively constant at levels of 31-70% and decreased gradually at levels of 71-100%. There was no significant difference in perfusion volume between smokers and non-smokers. Perfusion volume in COPD patients gradually decreased at levels of 31-60% and markedly decreased at levels greater than 60%. Perfusion volume differed significantly between COPD patients and healthy volunteers at levels of 41-100%. The mean PV/TPV value of COPD patients was significantly higher than that of healthy volunteers at levels of 21-40% and significantly lower than that of healthy volunteers at levels of more than 50%. This finding demonstrates that lung volume at high levels of pulmonary perfusion is decreased in COPD patients. The pulmonary perfusion volume at levels of more than 60% is an efficient means of distinguishing COPD patients from healthy subjects.