[Comparison of 99mTc-technegas scintigraphy and high resolution CT in pulmonary emphysema]

This study was undertaken to assess the usefulness of technetium-99m technegas scintigraphy axial images (technegas) compared with high resolution CT (HRCT) in 12 patients with pulmonary emphysema. All patients were male adult and heavy smokers and their mean age was 65. All patients inhaled 505 MBq technegas in several tidal volume breaths in the supine position without breath holding. SPECT imaging was performed by a Picker model Prism 2000. HRCT was performed after technegas. The technegas images showed different degree of changes from areas of heterogeneity to hot spots or defects. In emphysema, HRCT images showed low attenuation areas varying in size and number. In 4 of 12 patients, the degree of abnormal findings on technegas increased according to the degree of abnormal findings on HRCT. In the remaining 8 patients, however, more detailed findings were shown by technegas than by HRCT. There was no patients in which HRCT showed a greater changes than on technegas. HRCT can demonstrate low attenuation areas, even less than 5 mm in diameter. Moreover previous reports showed that aerosol inhalation would also demonstrate the airway disease. Assessment of the degree of involvement revealed by both methods indicated the superiority of technegas over HRCT. We conclude that technegas can represent the ventilation involvement easily more than HRCT in pulmonary emphysema.