Digital analysis of chest radiographs in pulmonary vascular congestion.

Twenty-five erect postero-anterior chest radiographs of 7 patients in and out of congestive heart failure, as well as 6 healthy controls, were graded as to severity of pulmonary vascular congestion. These visual gradings were compared with a vascular complexity index (VCI) computed after digitization of each radiograph. Good correlation was found between visual grading and the VCI (R = 0.77) and for assessing changes in a given patient (R = 0.95). In parallel animal experiments, correlation between the VCI and left-ventricular end-diastolic pressure (LVEDP) was also evaluated. Hypervolemia was induced in 5 dogs by infusion of dextran. LVEDP was measured in each catheterized erect animal and radiographs taken before and after infusion. Correlation between the VCI and LVEDP during infusion was good (R = 0.99).