Localization of pulmonary nodules with lipiodol prior to thoracoscopic surgery

Preoperative localization with lipiodol for identifying small or deeply seated pulmonary nodules is simple and useful for thoracoscopic surgery. Although several studies about performance and complication rates of lipiodol localization have been reported, there has been no report about the performance and complication rates of lipiodol localization with regard to the CT appearance of pulmonary nodules.

To evaluate the performance and complication rates of localization of pulmonary nodules with lipiodol prior to video-assisted thoracoscopic surgery with regard to the CT appearance of nodules.

After institutional review board approval and informed consent were obtained, lipiodol marking was performed in 67 patients (33 men and 34 women; mean age 58 years) with 68 nodules. All nodules were marked with 0.4-0.5 mL lipiodol under CT guidance on the day of surgery. The size of the targeted nodule and the shortest distance to the accessible pleural surface were measured. Lipiodol accumulation of a targeted nodule was scored by use of a four-point scale (0: none, 1: within 1 cm around a nodule, 2: partial accumulation within a nodule, 3: total accumulation within a nodule). Any complications after localization of nodules were noted. We analyzed the score of lipiodol accumulation and the presence of complications for the CT appearance of pulmonary nodules using the Mann Whitney U test, Fisher's exact test and the Kruskall Walis test.

The average nodule size was 11.4 mm (range 3.0-28.3 mm) and the average distance to the pleural surface was 13.7 mm (range 0-51.4 mm). Lipiodol accumulation scores of nodules were as follows: score 3 (n=19, 28%), score 2 (n=37, 54%), score 1 (n=11, 16%), and score 0 (n=1, 2%). Lipiodol accumulation scores of nodules were different according to the size of nodules (Kruskal Wallis test, p=0.023). Pneumothorax after localization occurred in 20 (29%) patients and the incidence was higher in nodules located in the subpleural area (Mann Whitney U test, p=0.048). Pulmonary hemorrhage along the needle tract occurred in five (7%) patients and was more frequent in patients with deep nodules as compared to shallow nodules (Mann Whitney U test, p < 0.001).

Lipiodol marking under CT guidance is a useful and safe procedure for the intraoperative localization of pulmonary nodules. Of variable CT findings, lesion size is important to determine the degree of lipiodol accumulation and the lesion depth is the most important feature for the development of postprocedural complications.