Detection of pulmonary edema and hemorrhage using indium-111 chloride images: rat model

Pulmonary edema and/or hemorrhage (PEH) induced by IV injection of norepinephrine was demonstrated in six rats by In-111 chloride lung/heart imaging. The anesthetized rats were positioned under a gamma camera using a pinhole collimator. After In-111 chloride IV injection, analog thorax images were obtained and dynamic data were recorded at 30 seconds/frame for 20 min before and after induced PEH. The gamma camera was interfaced to a computer which generated the curve of the lung/heart radioactivity ratio which rose from 0.4-0.5 at baseline to 1.0-1.4 at the end of the study. The image after IV norepinephrine injection showed a reversal of the lung/heart radioactivity concentration. In-111 chloride instantly binds to plasma transferrin yielding an excellent intravascular imaging agent. Leakage of this tracer into alevoli indicates loss of aveolar membrane wall competence. Pulmonary edema, as in acute respiratory distress syndrome, is difficult to diagnose radiographically and this In-111 chloride lung/heart imaging technique may be potentially useful.