Preoperative prediction of Ki-67 expression in hepatocellular carcinoma by spectral imaging on dual-energy computed tomography (DECT).

BACKGROUND

The Ki-67 expression level, which represents the proliferation status of cells, serves as a prognostic marker for hepatocellular carcinoma (HCC); however, the immunochemistry method currently used to evaluate Ki-67 is invasive and is not suitable for patients who have lost the chance for surgery, such as those with advanced tumors or those with other serious organic diseases. This study aimed to investigate the value of quantitative dual-energy computed tomography (DECT) parameters in predicting the expression level of Ki-67 in HCC.

METHODS

This study analyzed the data of 123 consecutive patients with HCC who underwent both Ki-67 immunohistochemistry analysis and two-phase contrast-enhanced DECT imaging. The patients were divided into the following two groups based on the positive rate of Ki-67 (Ki-67%): the high-expression group (Ki-67% >20%, n=74); and the low-expression group (Ki-67% ≤20%, n=49). The computed tomography (CT) values in the 130 and 140 keV monochromatic energy images (HU), normalized effective atomic number (NeffZ), fat density (D), and water density (D) were measured and calculated at the arterial phase (AP) and portal venous phase (PVP). A Spearman correlation coefficient analysis, a comparison of parameters between groups, a receiver operating characteristic (ROC) curve analysis for evaluating predictive efficacy, and a multivariable logistic regression analysis were conducted.

RESULTS

The NeffZ-AP, HU-PVP, HU-PVP, D-PVP, and D-PVP were positively correlated with the Ki-67% (all P<0.05), and the DECT parameter values in the high-expression group were significantly higher than those in the low-expression group (all P<0.05). The D-PVP [odds ratio (OR) =1.353, 95% confidence interval (CI): 1.204-1.521, P<0.001] and tumor diameter (OR =1.258, 95% CI: 1.08-1.465, P=0.003) were independent predictive factors for high Ki-67 expression. D-PVP had the highest predictive efficacy with an area under the curve (AUC) of 0.810. The multivariable analysis combining the DECT parameters and morphological characteristics improved the predictive efficacy of the model in predicting high Ki-67 expression (AUC =0.857).

CONCLUSIONS

DECT provides a non-invasive method to evaluate the proliferation status of HCC cells, and the predictive efficacy of high Ki-67 expression could be improved by combining DECT parameters and morphologic features.