肺大细胞神经内分泌癌的18F-FDG PET/CT表现

目的探讨肺大细胞神经内分泌癌（LCNEC）的18F-氟脱氧葡萄糖（FDG）PET/CT的影像学表现。方法回顾性分析2009年10月至2017年5月经病理证实的37例肺LCNEC患者的18F-FDG PET/CT影像学表现，包括病灶位置、形态特征、代谢和淋巴结转移情况，以及最大标准化摄取值（SUV_max）预测淋巴结转移的价值。SUV_max与肿瘤最大径的相关性采用Pearson相关性分析。结果37例肺LCNEC患者均为单发，其中周围型28例（28/37，75.7%）、中央型9例（9/37，24.3%）。30例病灶（30/37，81.1%）可见分叶征，多为浅分叶；10例病灶（10/37，27.0%）可见毛刺征。29例病灶（29/37，78.4%）边界清晰，9例病灶（9/37，24.3%）可见胸膜凹陷征，2例病灶可见液化坏死，1例病灶可见空洞形成，1例病灶内见点状钙化，1例病灶内见充气支气管征。37例病灶18F-FDG代谢程度均高于肝脏，SUV_max为11.7±5.2（3.3~25.3），肿瘤最大径为（3.2±1.5）cm，SUV_max与肿瘤最大径呈正相关（r=0.569，P=0.000）。15例病灶伴有肺门和（或）纵隔淋巴结转移，8例可见远处转移，包括骨转移4例、肾上腺转移1例、肝脏及骨转移2例、肾上腺及骨转移1例。约登指数最大为0.573，所对应的SUV_max为11.9，诊断效率最高，灵敏度为80.0%，特异度为77.3%。结论肺LCNEC的18F-FDG PET/CT多表现为周围型类圆形软组织结节或肿块，边缘清晰，充气支气管征少见，18F-FDG摄取较高。原发肿瘤SUV_max是判断淋巴结转移的重要半定量指标。

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

ObjectiveTo investigate the 18F-FDG PET/CT manifestations of pulmonary large cell neuroendocrine carcinoma(LCNEC).MethodsThe 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(SUV_max) for lymph node metastasis. Pearson's correlation was used to analyze the relation between primary tumor SUV_max and maximum tumor diameter.ResultsAll 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 SUV_max 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 SUV_max 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.ConclusionsThe 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 SUV_max is an important semi-quantitative indicator for predicting lymph mode metastasis.