Abstract
Background: Ultrasound (US)‐guided percutaneous acetic acid injection therapy (PAIT) is effective for patients with hepatocellular carcinoma (HCC). This study aimed to determine the occurrence and predictive value of persistent intra‐tumoral retention of acetic acid after PAIT. Methods: We prospectively studied 60 (52 M, mean age 68 ± 10 years) patients with 72 HCC nodules (45 ≤ 3 cm) treated with PAIT. The presence of post‐treatment persistent retention of acetic acid, defined as a homogeneous and highly hyperechoid mass in US appearance 3 days after completion of the treatment, was correlated with the treatment response. Results: The mean size of the treated tumour was 2.9 ± 1.0 cm (range 1.5–5 cm). Thirty (42%) HCC nodules showed complete tumour necrosis demonstrated by contrast‐enhanced dynamic CT. Complete response was found in 22 (69%) of 32 nodules showing persistent intra‐tumoral retention of acetic acid (P < 0.001). Small (≤3 cm) tumour size was also significantly associated with complete tumour necrosis (P = 0.001). There were no significant differences of the injection volume and treatment sessions between those with and without complete tumour necrosis in either small or large (>3 cm) HCC (P > 0.1). Multivariate logistic regression analysis showed that persistent retention of acetic acid (odds ratio (OR) 10.4, 95% confidence interval (CI) 3.1–34.7; P < 0.001) and tumour size ≤3 cm (OR 6.8, 95%, CI 1.8–25.8; P = 0.002) were independent factors predicting complete tumour necrosis. Conclusions: The presence of persistent retention of acetic acid is associated with a favourable response and may predict complete tumour necrosis after PAIT.