Objective To investigate the diagnostic value of chest enhanced computed tomography (CT) for mediastinal lymph node metastasis of esophageal cancer and the influencing factors for its accuracy.

Methods The retrospective case‑control study was conducted. The clinico⁃ pathological data of 463 patients with esophageal cancer who underwent surgical treatment in the First Affiliated Hospital of Army Medical University from July 2016 to June 2021 were collected. There were 385 males and 78 females, aged (61±8)years. Observation indicators: (1) results of pre-operative chest enhanced CT and postoperative pathological examination; (2) diagnostic value of chest enhanced CT for mediastinal lymph node metastasis of esophageal cancer; (3) influencing factors analysis of the diagnostic accuracy of chest enhanced CT for mediastinal lymph node metastasis of esophageal cancer. Measurement data with normal distribution were represented as Mean±SD, and count data were represented as absolute numbers and (or) percentages. Sensitivity, specificity, positive predictive value, negative predictive value and Youden index were used for authenticity evaluation of diagnostic value of chest enhanced CT for mediastinal lymph node metastasis of esophageal cancer, and accuracy and Kappa value were used for reliability evaluation. The higher the value of above indicators, the higher the authenticity and (or) reliability. The univariate analysis was conducted using the chi‑square test, and multivariate analysis was conducted using the binary Logistic regression model after including indicators with P<0.20 of univariate analysis.

Results (1) Results of preoperative chest enhanced CT and postoperative pathological examination. Of the 463 patients with esophageal cancer, mediastinal lymph node metastasis were diagnosed in 90 cases (including 35 cases of true positive and 55 cases of false positive) and no mediastinal lymph node metastasis were diagnosed in 373 cases (including 300 cases of true negative and 73 cases of false negative) by preoperative chest enhanced CT. Mediastinal lymph node metastasis were diagnosed in 108 cases and no mediastinal lymph node metastasis were diagnosed in 355 cases by postoperative patholo-gical examination. (2) Diagnostic value of chest enhanced CT for mediastinal lymph node metastasis of esophageal cancer. Authenticity evaluation of diagnostic value of chest enhanced CT for medias-tinal lymph node metastasis of esophageal cancer showed that sensitivity, specificity, positive predic-tive value, negative predictive value and Youden indexes were 32.41%(35/108), 84.51%(300/355), 38.89%(35/90), 80.43%(300/373), 0.169, respectively. Reliability evaluation showed that accuracy and Kappa value were 72.35%(335/463) and 0.180 (P<0.05), respectively. (3) Influencing factors analysis of the diagnostic accuracy of chest enhanced CT for mediastinal lymph node metastasis of esophageal cancer. Results of univariate analysis showed that the tumor diameter and the depth of tumor invasion were related factors affecting the diagnostic accuracy of chest enhanced CT for mediastinal lymph node metastasis of esophageal cancer (χ²=7.65, 6.07, P<0.05). Results of multi-variate analysis showed that the tumor diameter ≥2.1 cm was an independent risk factor affecting the diagnostic accuracy of chest enhanced CT for mediastinal lymph node metastasis of esophageal cancer (odds ratio=2.05, 95% confidence interval as 1.23‒3.43, P<0.05).

Conclusions The clinical value of chest enhanced CT for diagnosing mediastinal lymph node metastasis of esophageal cancer is limited, and the consistency with pathological results is quite different. The tumor diameter ≥2.1 cm is an independent risk factor affecting the diagnostic accuracy of chest enhanced CT for mediastinal lymph node metastasis of esophageal cancer