Standardized uptake value and radiological density attenuation as predictive and prognostic factors in patients with solitary pulmonary nodules: Our experience on 1,592 patients

Background: Multislice computed tomography (MSCT) increased detection of solitary pulmonary nodules (SPNs), changing the management based on radiological and clinical factors. When 18-fluorine fluorodeoxyglucose positron emission tomography combined with computed tomography (18F-FDG-PET/CT) was considered for the evaluation of nodules, the maximum standardized uptake value (SUVmax) more than 2.5 is used frequently as a cut off for malignancy. The purpose of this study is to evaluate SUVmax PET/CT and pulmonary attenuation patterns at MSCT in patients with SPN according to morphological and pathological characteristics of the lesion. Methods: A retrospective study on 1,592 SPN patients was carried out following approval by the Italian Registry of VATS Lobectomies. Results: All patients underwent VATS lobectomy. On histologic examination, 98.1% had primary or second metachronous primary lung cancers. In addition, 10.7% presented occult lymph node metastases (pN1 or pN2) on histological examination. Nodule attenuation on CT was associated with the histology of the lesion (p= 0.030); in particular, pure ground glass opacities (pGGOs) and partially solid nodules were related to adenocarcinomatous histotypes. Conversely, a significant relationship between SUVmax and age, nodule size, pathological node status (pN) was found (P=0.007, P=0.000 and P=0.002 respectively). Conclusions: Nodule attenuation can predict the histology of the lesion whereas SUVmax may relate to the propensity to lymph node metastases. Keywords: Solitary pulmonary nodule (SPN); maximum standardized uptake value; ground glass opacities; lymph node metastases; lung adenocarcinoma