Comments on characterization of solitary pulmonary nodules with 18F-FDG PET/CT relative activity distribution analysis

The solitary pulmonary nodule (SPN) is defined as focal parenchymal opacity of the lung, <3 cm in size, generally discovered incidentally during an X-rays examination (1), with a prevalence of 2.1% in non-selected populations. Subsequently, SPNs may be classified by computed tomography (CT), allowing better radiographic criteria as margins, size, density, contrast enhancement and calcification pattern (2), in order to ensure the diagnosis and correct identification between malignant lesions (metastases, primary tumors) and benign nodules (granulomas, abscess, vascular malformations). Despite these forewords, the correct diagnosis of SPNs by means of morphological criteria still represents a diagnostic dilemma (3).