Quantitative perfusion analysis of hepatocellular carcinoma using dynamic contrast enhanced ultrasound (CEUS) to determine tumor microvascularization

OBJECTIVE: The use of a standardized dynamic contrast enhanced ultrasound (CEUS) protocol to determine perfusion of hepatocellular carcinomas (HCC) using quantitative analysis. METHODS: Retrospective analysis of 27 patients with hepatocellular carcinoma examined by a standardized protocol (bolus injection of 2.4 ml sulphur hexafluoride microbubbles, arterial phase to portal venous phase using continuous CINE-loops over 1 minute, short CINE-loops after 2, 3, 4, 5 and 6 minutes and additional single images for B-mode, CCDS). The examination was performed by an experienced sonographer with a high resolution, multi-frequency transducer (1-6 MHz). The reading of the reference imaging (contrast enhanced CT and MRI) and histopathology, if necessary, was performed independently. Retrospective analysis of the CEUS DICOM loops was done using time intensity curve analysis (TIC) with evaluation of the time to peak (TTP) and the area under the curve (AUC). RESULTS: All tumor lesions were characterized by CEUS, based on typical contrast patterns for HCC lesions with arterial enhancement and wash out in the late phase, corresponding to MRI with liver specific contrast agent or contrast enhanced CT. Mean TTP (SD) in the tumor centre (C) was 19.93 (11.31), in the periphery (P) 22.94 (9.44) and in the normal liver tissue (LT) 28.19 (11.34) with significant differences between all zones C/P (p = 0.013), C/LT (p = 0.005) and P/LT (p = 0.022). AUC mean (SD) in the tumor centre (C) was 660.03 (292.64), in the periphery (P) 586.04 (237.01) and in the normal liver tissue (LT) 484.20 (236.99), also with significant differences between all zones C/P (p = 0.001), C/LT (p < 0.001) and P/LT (p < 0.001). CONCLUSION: TIC-analysis is an easy-to-use tool for the dynamic evaluation of microvascularization in hepatocellular carcinoma and allows a fast and cost-efficient quantitative analysis.