What is the clinical value of PET/CT in the diagnosis of pulmonary nodules?

The noninvasive diagnostic workup of solitary pulmonary nodules (SPNs) continues to be a challenge for radiologists and nuclear medicine physicians. Morphological evaluation is useful to differentiate between benign and malignant SPNs, but there is a considerable overlap between the benign and the malignant features, resulting in a large fraction of morphologically indeterminate SPNs. Integrated PET/CT with the glucose analogue ¹⁸F-fluorodeoxyglucose (FDG PET/CT) can simultaneously evaluate morphological characteristics, anatomic location and metabolic status of SPNs. FDG PET/CT has been shown to result in an overall improved accuracy for the detection of malignant SPNs. In addition, it is the most accurate technique for the staging of malignant SPNs. On the other hand, there are many causes for false positive or false negative FDG PET/CTs. Therefore, FDG PET/CT cannot replace histological evaluation of SPNs, but can be clinically helpful in specific subgroups of patients with SPNs. The goal of this review is to provide an overview of the literature on PET/CT imaging in SPNs and to describe several clinical scenarios for the use of FDG PET/CT in SPNs.