Localization Techniques

Abstract

In diagnostic imaging, the detection of mostly singular, isolated tumors is a frequent problem since they often cannot be qualified. In risk populations such as smokers, 65 % of patients present noncalcified lung nodules, with <5 % of lesions <1 cm being malignant. However, the incidence of malignancy increases dramatically above 1-cm lesion diameter (Diederich 2003). Even though lesion calcification helps to identify benign processes, lesion characterization by computed tomography (CT) or thorax radiography is unreliable. In unclear lesions with no previously known underlying malignancy, either follow-up imaging or percutaneous biopsy will usually be performed for further workup. In cases were either a primary lung cancer or limited metastastic disease is suspected, thoracic surgery will be considered. In recent years, thorax surgery has adopted lesser invasive approaches for confined lesions such as video-assisted thoracoscopic surgery (VATS). A problem often encountered during VATS is localizing the tumor, depending on its position relative to the lung surface. Pulmonary lesions located ≥5 mm from the visceral pleura with a diameter ≤10 mm are hard to find during VATS, and two-thirds of these cases need to be converted to open surgery (Suzuki et al. 1999). In these cases, preoperative marker placement is extremely helpful and significantly improves the surgeon’s technical success.