Segmental pulmonary anatomy in man: a method of study with angiography and single photon emission computed tomography

To study the appearance of the segmental pulmonary anatomy on single photon emission computed tomography (SPECT), 300 microCi of 99mTc-MAA was injected into one segmental pulmonary artery in patients who had elective cardiac catheterization for coronary artery disease and who had no pulmonary disease. Eighteen patients were enrolled in order to show the appearance of all pulmonary segments (10 in the right lung and 8 in the left lung). Planar and SPECT imaging were performed before and after peripheral intravenous injection of 3 mCi of 99mTc-MAA. Radioactivity in the segment was subtracted from that in the whole lung to show segmental perfusion defects on planar and SPECT whole lung images. Knowledge of the tomographic appearance of the pulmonary segments should make it easier to identify these segments on other imaging modalities that utilize sectional reconstruction, such as computed tomography and magnetic resonance imaging. This knowledge may also increase the specificity of pulmonary SPECT for the diagnosis of pulmonary emboli.