Sonographic evaluation for peripheral pulmonary nodules during video-assisted thoracoscopic surgery.

We express our opinion about the article of Yamamoto and associates. First, we congratulate them for the results they obtained in their study. We agree with author of the article [4] about the utility of intraoperative sonographic for locating peripheral pulmonary nodules. In our department, we have performed intrathoracoscopic localization of solitary pulmonary nodules. We think that intrathoracoscopic ultrasound is useful for locating not only pulmonary nodules, but also study structures around the nodule-like vessels, bronchi, and limphonodes. Moreover, we think intrathoracoscopic ultrasound also is useful for detecting resection margins. We think that intrathoracoscopic cannot play a role in the histology of the nodule [2, 3]. We have observed a frequent association between the final histology of the nodule and its ultrasound pattern. In fact, malignant pulmonary lesions have appeared as a homogeneous hypoechoic pattern with the sonographic disappearance of the hyperechoic pulmonary surface. Benign lesions often are associated with heterogeneous echogenicity. This sonographic pattern may be attributable to air bronchograms, the presence of different tissue, or hamartoma. However, we think this ultrasound pattern was not able to distinguish between benign and malign lesions. The Doppler can add something to the ultrasound pattern in defining the histology of the pulmonary nodule, but we are not sure it can determine intraoperative or final histology. We think it is impossible to base surgical treatment on the ultrasound or Doppler pattern alone because for us, only the intraoperative or final histology is sure and reliable. Ultrasound and Doppler patterns are only radiologic patterns, and although they give statistically significant results, they are not reliable for qualitative diagnosis of pulmonary lesions. Moreover, they are operator dependent [1]. We think that it currently is not ethically defensible to submit patients with a solitary pulmonary nodule to explorative thoracoscopy alone. Because the grade of intratumoral blood flow signal, as shown by Doppler, is low, we think that pulmonary resection with a frozen section of the specimen is mandatory. The Doppler pattern would play a role if this method is applied in the preoperative diagnosis, but it is impossible to perform a qualitative– quantitative study of a pulmonary nodule with percutaneous Doppler. We think, therefore, that it would be more correct to use ultrasound or Doppler only to locate and not to obtain a qualitative diagnosis of pulmonary nodules.