[Density and SUV ratios from PET/CT in the detection of mediastinal lymph node metastasis in non-small cell lung cancer]

Abstract

Background and objective: Mediastinal involvement in lung cancer is a highly significant prognostic factor for survival, and accurate staging of the mediastinum will correctly identify patients who will benefit the most from surgery. Positron emission tomography/computed tomography (PET/CT) has become the standard imaging modality for the staging of patients with lung cancer. The aim of this study is to investigate 18-fluoro-2-deoxy-glucose (18F-FDG) PET/CT imaging in the detection of mediastinal disease in lung cancer.

Methods: A total of 72 patients newly diagnosed with non-small cell lung cancer (NSCLC) who underwent preoperative whole-body 18F-FDG PET/CT were retrospectively included. All patients underwent radical surgery and mediastinal lymph node dissection. Mediastinal disease was histologically confirmed in 45 of 413 lymph nodes. PET/CT doctors analyzed patients' visual images and evaluated lymph node's short axis, lymph node's maximum standardized uptake value (SUVmax), node/aorta density ratio, node/aorta SUV ratio, and other parameters using the histopathological results as the reference standard. The optimal cutoff value for each ratio was determined by receiver operator characteristic curve analysis.

Results: Using a threshold of 0.9 for density ratio and 1.2 for SUV ratio yielded high accuracy for the detection of mediastinal disease. The lymph node's short axis, lymph node's SUVmax, density ratio, and SUV ratio of integrated PET/CT for the accuracy of diagnosing mediastinal lymph node was 95.2%. The diagnostic accuracy of mediastinal lymph node with conventional PET/CT was 89.8%, whereas that of PET/CT comprehensive analysis was 90.8%.

Conclusions: Node/aorta density ratio and SUV ratio may be complimentary to conventional visual interpretation and SUVmax measurement. The use of lymph node's short axis, lymph node's SUVmax, and both ratios in combination is better than either conventional PET/CT analysis or PET/CT comprehensive analysis in the assessment of mediastinal disease in NSCLC patients. .

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淋巴结与纵隔血池密度比的ROC曲线 ROC curve for node/aorta density ratio, with AUC of 0.755. AUC: area under the cure; ROC: receiver operating characteristic curve.

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淋巴结与纵隔血池摄取比的ROC曲线 ROC curve for node/aorta SUV ratio, with AUC of 0.780

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男性患者，60岁，右肺上叶鳞癌。PET示纵隔内异常高代谢灶（A），CT示纵隔内（4组）淋巴结短径为1.1 cm（B），PET/CT示纵隔内淋巴结SUVmax为4.7，原发灶SUVmax为9.2（C）。手术病理证实此枚淋巴结为良性淋巴结。 A 60-year-old man with squamous cell carcinoma in right upper lobe. The PET (A) image showed the abnormal uptake in the mediastinum (arrow). Mediastinal-window view of transverse CT (B) scan showed lymph node with short axis of 1.1 cm in 4R group (arrow). PET/CT (C) showed increased ¹⁸F-FDG uptake of mediastinal lymph node (arrow) and primary tumor (arrowhead) (SUVmax=4.7 and 9.2, respectively). This lymph node was negative for metastasis on the pathological examination. PET-CT: positron emission tomography/computed tomography.