Aim: To evaluate the response of hepatocellular carcinoma (HCC) to transarterial chemoembolization (TACE) using a simplified protocol of parametric contrast-enhanced ultrasound (pCEUS).
Methods: Eighteen patients with HCC (18 target tumors, diameter: 2.8-12 cm) were evaluated before, and 20 d after TACE. The distribution and morphology of TACE-induced necrosis in these tumors precluded accurate evaluation by visual assessment or by simple measurements. For pCEUS, a 4.8 mL bolus of SonoVue (Bracco, Milan, Italy) was intravenously administered and analysis of tumor perfusion during the initial phase of enhancement (0-30 s post injection) was performed with dedicated software (Qontrast, Bracco, Milan, Italy). Time-intensity curves were plotted and three parameters were calculated: peak intensity (PI, in percentage %), time to peak (TTP in seconds, s) and area under the curve during wash-in (AUC-WI, in arbitrary units, a.u). Magnetic resonance imaging was the standard imaging modality for post-treatment evaluation. Changes in tumor size were recorded and response was assessed according to response evaluation criteria in solid tumors criteria.
Results: A statistically significant decrease in PI and AUC-WI was observed in the treated tumors post TACE; PIpre: 21.5% ± 8.7% (mean ± SD), PIpost: 12.7% ± 6.7%, P < 0.001, AUC-WI pre: 17493 ± 9563 a.u, AUC-WI post: 9585 ± 5494 a.u, P < 0.001. A slight increase in TTP was noted post TACE, but this was not statistically significant; TTP pre: 13.1 ± 4.3 s, TTP post: 13.6 ± 4.2 s , P = 0.058). The changes in the aforementioned parameters were not accompanied by significant tumor shrinkage.
Conclusion: pCEUS, even when limited to the study of the arterial phase of tumoral enhancement, can detect and quantify early perfusional changes in HCC post TACE.
Keywords: Contrast-enhanced ultrasonography; Hepatocellular carcinoma; Parametric imaging; Transarterial chemoembolization.