99mTc-Technegas (Technegas) scintigraphy, including planar and SPECT images, was reviewed in patients who mainly had pulmonary emphysema. The Technegas images showed different degrees of change, from areas of heterogeneity to hot spots or defects. Comparison of planar and SPECT Technegas images revealed that more detailed findings were shown by SPECT than by planar images in mild cases. In more severe cases, the findings of SPECT and planar images were equivalent. In advanced stages, SPECT images should be excluded in favor of planar images. Technegas SPECT could demonstrate ventilation impairment more easily than 133Xe gas dynamic SPECT. The optical average score of Technegas in whole lung correlated well with forced expiratory volume in one second (FEV1.0) and FEV1.0/forced vital capacity. Technegas could assess ventilation impairment in pulmonary emphysema more easily than CT, especially in the upper lung field. Technegas was useful for the assessment not only of pulmonary emphysema but also of other diseases. For the quantitative evaluation of Technegas, some investigators study three-dimensional fractal analysis or mean voxel values of the lung. These quantitative analyses are useful for classifying clinical stage and comparing cases.