Primary Study Of The Value Of Gemstone Spectral Imaging (GSI) For Distinguishing Hepatic Tumors

Objective:To evaluate the preliminary application of GSI (Gemstone Spectral Imaging) in the diagnosis and differentiation of hepatic benign and malignant lesions.Methods:Twenty patients with hepatic tumors were undergone GSI scans by Discovery CT750 HD, including 5 primary hepatic carcinomas (PHC), 6 metastases, 5 hemangiomas and four cysts, to obtain the 70 keV monochromatic images and the iodine density images of different phases (arterial phase, portal venous phase and delayed phase). All the cases were analyzed with GSI viewer using different parameters of CT spectral imaging, such as spectral Hu curve, histogram and GSI scatterplot. The regions of interest (ROIs) were drawn on the iodine density images to measure the iodine concentrations in the hepatic lesions and the aorta, calculate the lesion-to-aorta ratio of iodine concentration and compare different lesions with two-sample t-test.Results:In all hepatic lesions, the hemangiomas had the highest iodine concentration of three phases, while the cysts had the lowest. The general trend of iodine concentration with different phases was similar for the PHCs and the metastases, their iodine concentrations were reduced alike in the delayed phase. The curves of the lesion-to-aorta ratio showed that the ratio of hemangioma was increasing largely in range and continually, while the ratios of the PHCs and the metastases rised little in the delayed phase. The iodine concentration and ratio in the delayed phase of the hemangiomas were higher than the PHCs and the metastases, the iodine concentration and ratio of the metastases in the portal venous phase and delayed phase were higher than the cysts, the iodine concentration and ratio of the PHCs were higher than the cysts in all three different phases, and all the discrepancies above were statistically significant (P<0.05). The two primary hepatic carcinomas had the parallel spectral curves of the arterial phase. The superposition of spectral Hu curves, histograms and GSI scatterplots was seen between the metastasis and the primary malignancy in one patient with colorectal cancer.Conclusion:The use of spectral CT with monochromatic images and the iodine density images of three different phases, and the measurement of iodine concentrations might be helpful for increasing the efficiency and accuracy of the detection and diagnosis of the hepatic tumors.