To assess the clinical value of acoustic radiation force imaging (ARFI) with virtual touch quantification (VTQ) technique in evaluating the efficacy of radiation therapy for unresectable hepatocellular carcinoma (HCC) patients with portal vein tumor thrombus (PVTT).

A total of 73 patients with unresectable HCC with PVTT who received radiotherapy at the Eastern Theater Command General Hospital, the First Affiliated Hospital of Nanjing Medical University, and Nanjing Jiangbei Hospital from January 2016 to December 2023 were retrospectively analyzed. All patients underwent routine ultrasound, ARFI, and enhanced CT examination one week before and one month after radiotherapy. The patients were divided into a downstaging group and non-downstaging group according to the PVTT downstaging rate. Univariate and multivariate Logistic regression models were used to analyze the correlation of clinicopathologic parameters and, ARFI characteristics with the downstaging rate of the two groups of patients. According to the results of multivariate Logistic regression, statistically significant parameters were incorporated into the multivariate Cox survival analysis model, and factors independently related to the survival outcome of patients were identified.

After radiotherapy, the downstaging rate of PVTT was 35.62% (26/73), the upstaging rate was 4.11% (3/73), and the stable rate was 60.27% (44/73). Univariate analysis showed that there were significant differences in alpha-fetal protein (APF) level before and after radiotherapy, cirrhosis degree, HCC differentiation degree, shear wave velocity (SWV) before and after radiotherapy, and SWV change rate between the downstaging group and non-downstaging group (P<0.05). Multivariate Logistic regression analysis showed the degree of cirrhosis (severe: odds ratio [OR]=9.671, 95% confidence interval [CI]: 1.420-65.887, P=0.020), the differentiation degree of HCC (intermediate: OR=0.158, 95%CI: 0.026-0.950, P=0.044; low/undifferentiation: OR=3.216, 95%CI: 0.541-19.115, P=0.045), AFP level >14 ng/ml after radiotherapy (OR=11.890, 95%CI: 2.274-62.169, P=0.003), and SWV change rate ≤20% (OR=15.675, 95%CI: 2.008-122.353, P=0.009) were independently correlated with the patients' downstaging rate. Multivariate Cox survival analysis showed that AFP level >14 ng/ml (OR=2.133, 95%CI: 1.188-3.830, P=0.011), HCC differentiation degree (low/undifferentiation: OR=4.041, 95%CI:1.823-8.959, P=0.001), and SWV change rate ≤20% (OR=2.649, 95%CI: 1.450-4.842, P=0.002) were independently associated with survival outcome.

The level of APF after radiotherapy, the degree of differentiation of HCC, and the change rate of SWV are significantly correlated to whether PVTT has been downstaged or not and correlated with the survival outcome of unresectable HCC patients with PVTT, which are important indicators to evaluate the efficacy of radiotherapy. VTQ is an effective method to evaluate the efficacy of radiotherapy for HCC combined with PVTT, and can provide imaging evidence for clinical decision-making.