Preoperative Diagnosis of 18F-FDG PET/CT on Regional Lymph Node Metastasis in Colorectal Cancer / 中国医学影像学杂志

ABSTRACT

Purpose To discuss the diagnostic value and the optimal diagnostic threshold of preoperative 18F-FDG PET/CT imaging on regional lymph node metastasis in colorectal cancer.Materials and Methods Seventy-six patients with newly diagnosed colorectal cancer underwent radical resection of colorectal cancer within one week after PET/CT examination.All lymph nodes matching PET/CT were divided into proximal and distal lymph nodes on the basis of their location relative to the primary tumor.Meanwhile,the receiver operating characteristic (ROC) curves of the lymph node short diameter and maximum standardized uptake value (SUVmax) were created according to the pathological findings which were considered as the gold standard,and the diagnostic efficacies were analyzed.Results The proximal and distal lymph node ROC curves showed that the optimum thresholds of lymph node short diameter,SUVmax were 6.5 mm,1.9 and 5.5 mm,1.81.The sensitivity,specificity and accuracy of the diagnosis of proximal lymph node metastasis under the optimum threshold of lymph node short diameter were 84.85％,73.02％ and 77.52％,respectively;and those of distal lymph node metastasis were 97.62％,65.45％ and 79.38％,respectively.The sensitivity,specificity and accuracy of the diagnosis of proximal lymph node metastasis under the optimum threshold of SUVmax were 84.85％,95.81％ and 91.64％,respectively;those of distal lymph node metastasis were 92.86％,94.55％ and 93.81％,respectively.The specificity and accuracy of the optimum threshold of SUVmax were higher than those of the optimum threshold of lymph node short diameter (P＜0.01).The homogeneity of optimum threshold of SUVmax was excellent in comparison with the pathological results (Kappa=0.813 and 0.874,P＜0.01).Conclusion Optimum threshold method improves the diagnostic efficacy of 18F-FDG PET/CT in regional lymph node metastasis of colorectal cancer.Moreover,the SUVmax standard is superior to lymph node short diameter standard.