Mistargeting after fusion imaging-guided percutaneous radiofrequency ablation of hepatocellular carcinomas

Purpose To evaluate the incidence and causes of mistargeting after fusion imaging-guided percutaneous radiofrequency (RF) ablation of hepatocellular carcinomas (HCCs). Materials and Methods Between September 2011 and March 2013, 955 HCCs in 732 patients were treated with percutaneous RF ablation. Among them, ablation of 551 HCCs was accomplished under fusion imaging guidance, and seven mistargetings were noted in seven patients (male-to-female ratio = 6:1; mean age, 60.1 y; range, 47-73 y). The incidence of mistargeting and the cause of liver disease in the patients with mistargeting were evaluated. The causes of mistargeting were assessed according to the following classification: small size of HCC, subcapsular location, subphrenic location, confusion with pseudolesions, poor conspicuity of HCC, poor sonographic window, and poor electrode path. Results The incidence of mistargeting after fusion imaging-guided RF ablation was 1.3% (7 of 551). All patients with mistargeting were hepatitis B virus carriers. The most common cause of mistargeting was the small size of HCC (100%; 7 of 7), followed by confusion with surrounding pseudolesions (85.7%; 6 of 7), subcapsular (71.4%; 5 of 7) and subphrenic locations (71.4%; 5 of 7), poor conspicuity of the HCC (71.4%; 6 of 7), poor sonographic window (28.6%; 2 of 7), and poor electrode path (28.6%; 2 of 7). Conclusions The incidence of mistargeting after fusion imaging-guided RF ablation was 1.3%. The most common cause of mistargeting was the small size of HCC, followed by confusion with surrounding pseudolesions, subcapsular and subphrenic locations, and poor conspicuity of the HCC.