[Quantitative evaluation of regional pulmonary functions after lung resection using three-dimensional images of ventilation and perfusion SPECT].

To evaluate changes after Lobectomy in the regional functions of the remaining lung and of the unaffected lung, three-dimensional (3-D) images of lung ventilation and perfusion SPECT were studied. In 60 patients who underwent lung resection, ventilation (99m Tc-phytate aerosol inhalation) and perfusion (99m Tc-MAA) SPECT were performed before and one month after operation. 3-D images were obtained from SPECT by the volume-rendering method setting thresholds at three levels, and the 3-D functional capacity of the right and left lung was determined at a threshold of 25%. Changes were evaluated using the ratio of the value obtained after operation to the one obtained before operation. The remaining rate of perfusion in the remaining lung was 0.58 +/- 0.22 after the right upper lobectomy, 0.32 +/- 0.04 after the right upper & middle bilobectomy, 0.86 +/- 0.11 after the right middle lobectomy, 0.55 +/- 0.17 after the right lower lobectomy, 0.24 +/- 0.18 after the left upper lobectomy, 0.46 +/- 0.05 after the left lower lobectomy, and 0 after the left pneumonectomy. The remaining rate was significantly low in the right upper & middle bilobectomy and the left upper lobectomy. The large decrease in the rate in these operations was considered to have resulted from a shift of the remaining lung towards the head and excessive expansion of the remaining lung. The distribution of the aerosol inhalation decreased more significantly than that of perfusion in almost all patients. The remaining rate of ventilation of the remaining lung after the lower lobectomy was lower than that after the upper lobectomy. This may have been due to the characteristics of the aerosol practices. We found that changes in the regional functions of the lung after lung resection can be topographically and quantitatively evaluated by 3-D image processing of pulmonary ventilation and perfusion SPECT, such analysis is usefulness in evaluation of function preservation operation.