Regional Pulmonary Distribution of Iodine-125-Labeled Oleic Acid Its Relationship to the Pattern of Oleic Acid Edema and Pulmonary Blood Flow

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Abstract
Tarver RD, Tsai J, Hedlund LW, Sullivan DC, Lischko MM, Harris CC, Effmann EL, Putman CE. Regional pulmonary distribution of iodine-125-labeled oleic acid: its relationship to the pattern of oleic acid edema and pulmonary blood flow. Invest Radiol 1986;21:102–107. Oleic acid infusion in dogs produces a patchy, predominantly peripheral lesion on CT scans. This study correlates the pattern of oleic acid injury with the distribution of infused oleic acid and pulmonary blood flow. Radiolabeled oleic acid (1–125,0.05 ml/kg) and radiolabeled 15-micron microspheres (Co-57) were infused into the right atria of 11 dogs. Oleic acid was given after the microspheres in six dogs and before microspheres in five dogs. Ten minutes after infusion, the lungs were removed. Four transverse slices (0.5 cm thick) of the lower lobes were taken from each dog and cubed. Samples were grouped into three regions of the transverse slice: outer, middle, and inner concentric rings. In both groups, 1–125 (oleic acid) activity was greater in the outer than the middle and inner concentric layers (P < 0.001). When Cobalt-57 microspheres were given before oleic acid, Cobalt-57 activity was marginally lower in the outer layer compared with the middle and inner layers. However, when oleic acid was given first, microsphere activity in the outer layer was significantly lower (P < 0.001) than the middle layer. Thus, oleic acid was preferentially distributed to the peripheral regions of the lung, similar to the regions of injury on CT. This distribution did not correspond to the pattern of pulmonary blood flow as indicated by the microspheres. Immediately after oleic acid infusion, pulmonary blood flow to the periphery was reduced, reflecting a response to the predominantly peripheral injury by oleic acid.