Invited commentary

Abstract

In this article, Daniel and colleagues describe preoperative CT guided radiotracer localization of small pulmonary nodules using 99mTc MAA prior to thoracoscopic wedge resection. The common preoperative marking methods—hookwire placement or methylene blue dye injection—are generally good but not without failures or complications. Hookwire displacement or inability to recognize methylene blue dye on the pleural surface are responsible for considering conversion to open surgery. Radioguided searching allowed detection of all injected lesions. Technetium compounds have long half-lives (6 hours), so it is suitable for preoperative localization and some delay between labeling and operation.Several marking techniques using a radiotracer—specially human serum albumin, tin colloid, phytate, and sulfa colloid—for thoracoscopic resection of small pulmonary nodules have already been reported. One of the most important concerns for localizing of small pulmonary nodules using radiotracer is “the size of particle”. Diffusion of the injected radioisotope, which is dependent on the size of particles, causes difficulty during thoracoscopic wedge resection of small pulmonary nodules. As occurs with some dyes, the isotope will not spread into the lung parenchyma or bronchus if it is big enough to remain at the injection site. Radioactivity is detected as small hot spots on the lung surface in patients. To improve this technique, larger radioactive particles may be useful for preventing diffusion of the injected isotope and decrease the dosage of radioactivity.In this study, the authors use the 99mTc MAA with a particle size of approximately 10–50 μm. This radioisotope is larger than that of human serum albumin (approximately 10 nm), sulfa colloid (approximately 100 nm), phytate (approximately 200–100 nm), and tin colloid (approximately 400–1500 nm), used in previous reports. By using larger radioactive particles, the authors succeeded in decreasing the dosage of radioactivity for injection, 0.1 ml/0.3 mCi of 99mTc MAA. This is the most valuable contribution in this article.Preoperative radiolocalization may be one of the effective localization procedures with less complication and failure, and this technique using larger radioactive particles seems to be more suitable than other radiolocalization methods. This study should contribute to the development of preoperative localization methods for small pulmonary nodules for thoracoscopic resection, and is certainly worthy of further study. In this article, Daniel and colleagues describe preoperative CT guided radiotracer localization of small pulmonary nodules using 99mTc MAA prior to thoracoscopic wedge resection. The common preoperative marking methods—hookwire placement or methylene blue dye injection—are generally good but not without failures or complications. Hookwire displacement or inability to recognize methylene blue dye on the pleural surface are responsible for considering conversion to open surgery. Radioguided searching allowed detection of all injected lesions. Technetium compounds have long half-lives (6 hours), so it is suitable for preoperative localization and some delay between labeling and operation. Several marking techniques using a radiotracer—specially human serum albumin, tin colloid, phytate, and sulfa colloid—for thoracoscopic resection of small pulmonary nodules have already been reported. One of the most important concerns for localizing of small pulmonary nodules using radiotracer is “the size of particle”. Diffusion of the injected radioisotope, which is dependent on the size of particles, causes difficulty during thoracoscopic wedge resection of small pulmonary nodules. As occurs with some dyes, the isotope will not spread into the lung parenchyma or bronchus if it is big enough to remain at the injection site. Radioactivity is detected as small hot spots on the lung surface in patients. To improve this technique, larger radioactive particles may be useful for preventing diffusion of the injected isotope and decrease the dosage of radioactivity. In this study, the authors use the 99mTc MAA with a particle size of approximately 10–50 μm. This radioisotope is larger than that of human serum albumin (approximately 10 nm), sulfa colloid (approximately 100 nm), phytate (approximately 200–100 nm), and tin colloid (approximately 400–1500 nm), used in previous reports. By using larger radioactive particles, the authors succeeded in decreasing the dosage of radioactivity for injection, 0.1 ml/0.3 mCi of 99mTc MAA. This is the most valuable contribution in this article. Preoperative radiolocalization may be one of the effective localization procedures with less complication and failure, and this technique using larger radioactive particles seems to be more suitable than other radiolocalization methods. This study should contribute to the development of preoperative localization methods for small pulmonary nodules for thoracoscopic resection, and is certainly worthy of further study.