Preoperative Diagnosis of Regional Lymph Node Metastasis of Colorectal Cancer With Quantitative Parameters From Dual-Energy CT.

OBJECTIVE. The purpose of this study was to investigate the performance of quantitative parameters derived from dual-energy CT (DECT) in the preoperative diagnosis of regional metastatic lymph nodes (LNs) in patients with colorectal cancer. SUBJECTS AND METHODS. Triphasic contrast-enhanced DECT was performed for 178 patients with colon or high rectal cancer. The morphologic criteria, short-axis diameter, and quantitative DECT parameters of the largest regional LN were measured and compared between pathologically metastatic and nonmetastatic LNs. Univariate and multivariable logistic regression analyses were used to determine the independent DECT parameters for predicting LN metastasis. Diagnostic performance measures were assessed by ROC curve analysis and compared by McNemar test. RESULTS. A total of 178 largest LNs (72 metastatic, 106 nonmetastatic) were identified in 178 patients. The best single DECT parameter for differentiation between metastatic and nonmetastatic LNs was normalized effective atomic number (Zeff) in the portal venous phase (AUC, 0.871; accuracy, 84.8%). These values were higher than those of morphologic criteria (AUC, 0.505-0.624; accuracy, 47.8-62.4%) and short-axis diameter (AUC, 0.647; accuracy, 66.3%) (p < 0.05). The diagnostic accuracy of combined normalized iodine concentration in the arterial phase and normalized effective atomic number in the portal venous phase was further improved to 87.1% (AUC, 0.916). CONCLUSION. Quantitative parameters derived from DECT can be used to improve preoperative diagnostic accuracy in evaluation for regional metastatic LNs in patients with colorectal cancer.