A prospective study of dual-energy CT in determining the metastatic and non-metastatic lymph nodes of colorectal cancer

Abstract Background To explore the ability of Dual-energy CT (DECT) to differentiate metastatic from non-metastatic lymph nodes in colorectal cancer (CRC). Methods Seventy-one patients with primary CRC underwent contrast-enhanced DECT imaging before surgery. The colorectal specimen was scanned after surgery, and lymph nodes were matched to the pathology report. The DECT quantitative parameters were analyzed: dual-energy curve slope value(λHU), standardized iodine concentration (n△HU), iodine water ratio (nIWR), electron density value (nρeff), and effective atom-number (nZ), for the metastatic and non-metastatic lymph node differentiation. Also, sensitivity and specificity analyses were performed by using receiver operating characteristic curve. Results One hundred and fifty lymph nodes including 66 non-metastatic and 84 metastatic lymph nodes were matched using the radiological-pathological correlation. Metastatic node had a significantly greater λHU, n△HU and nIWR values than non-metastatic node in both arterial and venous phases (P < 0.01). The AUC, sensitivity and specificity were 0.80, 80.30% and 65.48% for λHU; 0.86, 69.70% and 95.24% for n△HU; 0.88, 71.21% and 95.24% for nIWR in the arterial phase. No significant difference was found in electron density and effective Z value for differentiation. Conclusion Dual-energy CT quantitative parameters may be helpful in diagnosing metastatic lymph nodes of CRC.