Background: The purpose of this study was to develop and evaluate radiotracer-guided localization of small or ill-defined pulmonary nodules for thoracoscopic excisional biopsy.
Methods: This study consisted of two parts: a laboratory study in rats to determine the most suitable radiotracer, and a pilot study in humans to determine the feasibility of radiotracer lung nodule localization. The right lung of 12 rats was injected with a technetium 99m (Tc 99m) based radiotracer solution: 4 each with macroaggregated albumin (MAA), unfiltered sulfur colloid (SC), and pertechnetate (TcO(4)). Serial imaging was performed using a small animal gamma camera for 4 hours following injection. In 13 patients, computed tomographic (CT) guided injection of Tc 99m MAA solution was made into or adjacent to a pulmonary nodule suspicious for primary lung cancer. Gamma probe localization of the nodule was performed during subsequent thoracoscopic surgery.
Results: In the animal model, MAA provided more precise localization than SC or TcO(4) and was selected for the human study. In the human series, all 13 patients had successful gamma probe localization of their lesion. There were no radiologic or surgical complications. Seven of 13 nodules were malignant, and five of these nodules were stage IA primary lung carcinomas.
Conclusions: Computed tomographic-guided radiotracer localization of small or ill-defined pulmonary nodules using Tc 99 m MAA before thoracoscopic excisional biopsy is feasible and may make excisional biopsy the preferred management strategy for the management of small pulmonary nodules in patients at high risk for malignancy.