Direct lipiodol injection used for a radio-opaque lung marker: stability and histopathologic effects

The objective of this study was to evaluate the effects on the histopathologic findings of directly injected lipiodol into lung and to identify the existence of remaining lipiodol in the lung according to the follow-up time. Forty rats were randomly assigned to 1 of 4 groups: group I (n = 10) served as the control group and received 0.2 mL of normal saline; groups II (n = 10), III (n = 10), and IV (n = 10) served as experimental groups and received 0.1-0.2 mL of lipiodol under fluoroscopy. At 3 hours (groups I and II), 24 hours (group III), and 1 week (group IV) after injection, the radiographic presence of lipiodol and histopathologic findings of each group were evaluated. Minimal acute lung injuries developed and the radio-opaque lipiodol nodule remained in group II. In group III, acute lung injuries were the most serious. However, acute injuries disappeared and foamy macrophages accumulated within the alveolar space in group IV. In this group, remaining lipiodol was also identified on radiograph. Directly injected lipiodol caused acute lung injury, which disappeared at 1 week along with the resolving process. On radiographs, directly injected lipiodol remained after 1 week. Lipiodol could be used as a safe and stable biomaterial for marking pulmonary nodules.