Determination of the pleural edge by gamma-ray transmission computed tomography

A technique is described for transaxial imaging of the thorax during pulmonary perfusion study. The contours of the air-containing lungs were obtained by gamma-ray transmission data from a Tc-99m plane flood source. These images were overlaid on the emission tomogram of the pulmonary blood flow obtained with Tc-99m MAA. It permits reliable detection of peripheral perfusion defects. Use of the results from these measurements can be applied to evaluate marginal hypoperfusions of the lungs.