Quantitative assessment of the degree of differentiation in colon cancer with dual-energy spectral CT.

Abstract

To evaluate dual-energy spectral CT imaging in evaluating the degree of differentiation in colon cancer. Forty-seven colon cancer patients underwent spectral CT during arterial phase (AP) and portal venous phase (PP), and were characterized pathologically differentiated to well-differentiated (A, n=18) and poorly differentiated or undifferentiated carcinoma group (B, n=29). Lesion iodine concentration (IC) was measured and normalized to that of aorta (NIC). CT numbers were measured and the slope (λ HU) of the spectral HU curve was calculated. These parameters were statistically compared between the two groups. ROC curves were used to evaluate their diagnostic efficacies. There were significant differences in IC (1.01±0.20 vs. 1.59±0.57mg/ml), NIC (0.12±0.03 vs. 0.19±0.09), λ HU (1.41±0.29 vs. 2.03±0.85), and CT number at 70keV (48.61±9.03HU vs. 63.97±15.86HU) between groups A and B in AP (p<0.05), but no difference in PP. Using IC=1.13mg/ml in AP as the threshold, one obtained a sensitivity of 81.8% and a specificity of 71.4% for differentiating well-differentiated from poorly differentiated or undifferentiated carcinoma. These values were statistically higher than those (64.7% and 62.3%) using CT number at 70keV. Spectral CT imaging parameters (IC, NIC, and λ HU) in AP provide improved accuracy for evaluating the degrees of differentiation in colon cancer than CT number at 70keV.