The role of positron emission tomography in the diagnosis of indeterminate solitary lung nodule

Lung cancer is one of the most common malignancies in the world, being the major cause of death in Italy. About 130,000 new solitary pulmonary nodules (SPN) are identified each year in the United States. The classification of a nodule as benign, on the basis of computed tomography (CT), is not always possible, and a significant number of nodules, remains undetermined. Over 40% of non calcified SPN observed on chest x-ray are benign. Biopsy procedures, including thoracoscopy and thoracotomy, are therefore used, but half of the lesions removed are benign and would not necessitate a surgical procedure. Positron Emission Tomography with [18F]fluoro-deoxy-glucose (FDG-PET) provides physiologic and metabolic information that define the CT undetermined nodules. FDG-PET imaging is an excellent method for assessing the nature of these nodules, with sensitivity, specificity and accuracy of 96%, 73% and 900% respectively. Although the presence of false negative (lesions less than 5 mm in diameter, carcinoid and bronchoalveolar carcinoma and hyperglycemia) and false positive findings (inflammatory conditions), the high negative predictive value of FDG-PET suggest to limit biopsy only to those patients with positive findings.