Local tumour progression after loco-regional therapy of hepatocellular carcinomas: Value of fusion imaging-guided radiofrequency ablation

Abstract

To assess the value of fusion imaging of real-time ultrasonography (US) with liver computed tomography (CT)/magnetic resonance imaging (MRI) images for planning US of radiofrequency ablation (RFA) in improving conspicuity of the lesions and reducing false-positive detection of local tumour progression (LTP) found after transcatheter arterial chemoembolization (TACE) or RFA of hepatocellular carcinoma (HCC). This study was approved by the institutional review board and informed consent was waived. Fifty patients with LTP (mean ± SD, 1.5 ± 0.6 cm; range 0.5-3 cm) detected at follow-up CT or MRI were included. Planning US was performed by two radiologists using conventional US first and fusion imaging later in the same session. False-positive detection rates were assessed using conventional US based on the results of fusion imaging. The number cases of initially invisible tumours on conventional US that became visible after image fusion were also evaluated. The true-positive detection rate and conspicuity scores of the index tumours were compared between conventional US and fusion imaging. On conventional US, 40 (80%) out of 50 HCCs with LTP were identified. However, the false-positive detection rate of conventional US was 12.5% (5/40). Out of 10 initially invisible HCCs with LTP on conventional US, six (60%) became visible after image fusion. The true-positive detection rate on conventional US was 70% (35/50), whereas it was increased to 92% (46/50) after image fusion (p = 0.0026). Fusion imaging can improve the conspicuity of lesions and reduce the false-positive detection of LTP after TACE or RFA.