18F-FDG PET/CT manifestations of pulmonary large cell neuroendocrine carcinoma

Abstract

Objective To investigate the 18F-FDG PET/CT manifestations of pulmonary large cell neuroendocrine carcinoma(LCNEC). Methods The 18F-FDG PET/CT manifestations of 37 lung LCNEC patients confirmed by pathology from October 2009 to May 2017 were analyzed. These manifestations include lesion location, shape characteristics, lymph node metastasis, lesion metabolism, and predictive value of primary tumor maximum standardized uptake value(SUVmax) for lymph node metastasis. Pearson's correlation was used to analyze the relation between primary tumor SUVmax and maximum tumor diameter. Results All 37 patients with lung LCNEC were with single lung node, including 28 patients located peripherally(28/37, 75.7%) and 9 patients located centrally(9/37, 24.3%). Lobulation of tumors was found in 30 cases(30/37, 81.1%), and spiculation was observed in 10 cases(10/37, 27.0%). The tumors were smooth and well defined in 29 cases(29/37, 78.4%), whereas pleural indentation, necrosis, cavity, calcification, and air bronchograms were found in 9, 2, 1, 1, and 1 cases, respectively. The metabolism of 18F-FDG in 37 lesions was higher than that in the liver. The SUVmax was 11.7±5.2(3.3-25.3), and the maximum tumor diameter(3.2±1.5) cm. These two parameters showed a positive correlation(r=0.569, P=0.000). Mediastinal and/or hilar lymphadenectasis was observed in 15 cases. Distant metastasis was observed in 8 cases, including bone metastasis in 4 cases, adrenal gland metastasis in 1 cases, liver and bone metastasis in 2 cases, and adrenal gland and bone metastasis in 1 case. Primary tumor SUVmax had a predictive value for lymph node metastasis. When the cut-off value was 11.9, the Youden index was 0.573, and the diagnostic efficiency was the highest with 80% sensitivity and 77.3% specificity. Conclusions The 18F-FDG PET/CT manifestations of most pulmonary large cell neuroendocrine carcinoma are characterized by round soft tissue nodules or masses with clear margins, rare air bronchograms, and high 18F-FDG uptake. Primary tumor SUVmax is an important semi-quantitative indicator for predicting lymph mode metastasis. Key words: Lung neoplasms; Neuroendocrine carcinoma; Positron emission tomography computed tomography; Fluorodeoxyglucose F18