An Index of Pulmonary Edema Measured with Emission Computed Tomography

Abstract

Positron camera and short-lived biological isotopes are used to obtain transverse sections of lung volume, blood volume and total lung water of dog lungs to assess the degree of pulmonary edema in normal and edematous dogs. At equilibration with specific isotope, 30 equally spaced angular profiles of the distribution are collected to obtain transverse section images. Emission computed number is obtained in the lung and heart areas for the images obtained with an intravascular marker (11CO) and intra- and extravascular marker (C15O2). The emission computed number ratio of lung to heart for C15O2 images is an index that is related to degree of edema. Emission computed number related to extravascular water can be obtained from normalized (C15O2 - 11CO) scintigrams. The technique is noninvasive.