Hepatocellular Carcinoma Treated with Transarterial Chemoembolization: Dynamic Perfusion-CT in the Assessment of Residual Tumor

Aim: To asses the value of computed tomography (CT)-perfusion in the detection of residual hepatocellular carcinoma (HCC) vascularization after transarterial chemoembolization (TACE).

Methods: Thirty-two consecutive patients were prospectively included in this study. All patients had liver cirrhosis and a confirmed HCC lesion which was treated with TACE. One month after treatment, perfusion measurements of treated lesions were carried out. The CT-perfusion (CT-p) protocol was performed with 16 slice multidetector computed tomography which included the following parameters: 8 dynamic slices/scan per 40 scans after iv injection of 50 mL of iodinated contrast (350 mg/mL) at a flow rate of 6 mL/s. Treated lesions were evaluated using dedicated perfusion software, which generated a quantitative colour map of perfusion. The following parameters were considered: hepatic perfusion (HP), arterial perfusion (AP), blood volume (BV), hepatic perfusion index (HPI), and time to peak (TTP). Perfusion parameters were described with quartile values of their distribution and statistically analyzed.

Results: Perfusion parameters of the treated lesions could be quantitatively assessed using CT-p analysis. The presence of residual tumor tissue was observed in 13 of the 32 patients. The values of the perfusion parameters measured within the relapse tissue were: HP (mL/100 g per minute): median = 44.4 (1(st)qt = 31.3, 3(rd)qt = 55.8); BV (mL/100 g): median = 18.7 (1(st)qt = 11.5, 3(rd)qt = 22.5); AP (mL/min): median = 39.0 (1(st)qt = 36.5, 3(rd)qt = 61.3); HPI (%): median = 34.0 (1(st)qt = 30.4, 3(rd)qt = 38.9); TTP (s): median = 17.3 (1(st)qt = 15.8, 3(rd)qt = 26.5). With the use of the univariate paired Wilcoxon signed rank test, HP, AP and HPI were shown to be significantly higher (P < 0.001) in the relapse site than in the primary lesion. The BV and TTP parameters showed a tendency to be greater and lower, respectively, in the relapse site than in the primary lesion.

Conclusion: In patients with HCC treated with TACE, CT-p provides measurement of flow parameters related to residual arterial structures in viable tumor, thus helping in the assessment of therapeutic response.