Oleic acid-induced lung injury: Thin-section CT evaluation in dogs

PURPOSE: To validate lung attenuation measurements for quantifying extravas cular lung water in oleic acid-induced pulmonary edema, compare subjective assessment with attenuation measurements, and compare this permeability-typ e pulmo nary edema with hydrostatic-type pulmonary edema. MATERIALS AND METHODS: Thin-section computed tomography (CT) and pulmonary hemodynamic examinations were performed sequentially in six dogs before and after intravenous administration of 0.08 mg of oleic acid per kilogram of body weight. Extravascular lung water and pulmonary capillary pressure were measured. Results were compared with those reported in a canine model of h ydrostatic edema. RESULTS: Oleic acid induced a progressive increase in extravascular lung wa ter without a change in capillary pressure, which indicated pure permeabili ty-type edema. Ground-glass opacification was detected as soon as extravasc ular lung water increased. Lung attenuation was highly correlated to extrav ascular lung water (r = 0.76, P < .001) as in hydrostatic edema, but was ch aracterized by an almost absent gravitational gradient. CONCLUSION: Thin-section CT is sensitive for early detection and quantifica tion of oleic acid-induced pulmonary edema in a canine model. Different fro m early canine,hydrostatic edema, which is characterized by a gravitational gradient, early oleic acid-induced pulmonary edema in a supine dog is char acterized by nearly homogeneous distribution, except for ventral sparing.