Hepatobiliary phase MRI-guided radiofrequency ablation of small hepatocellular carcinomas invisible on precontrast...

In cirrhotic livers reliable visualization and exact localization of small hepatocellular carcinoma (HCC) can be challenging without adequate contrast enhancement. To investigate the feasibility, technical success rate, and safety of hepatobiliary phase MRI-guided percutaneous radiofrequency ablation (RFA) of small HCCs invisible on precontrast MRI.

53 patients (17f, 63.6 ± 16.7 years), with small HCC that were not visible in non-contrast MRI underwent MRI guided RFA. Feasibility was assessed by analyzing proper identification of the target tumor, tumor delineation during MRI-guided needle positioning and number of needle adjustments required for accurate placement. Technical success was defined as complete ablation with a safety margin of 5 mm. Safety was assessed from reports of procedure-related complications.

In all 53 cases, target tumors were not visible in non-contrast MRI but in the hepatobiliary phase. In 5 cases, planning imaging showed new tumors, which were either treated in the same session (n = 4) or altered the therapeutic approach (n = 1). Mean tumor diameter was 9.7 ± 1.9 mm and the number of needle adjustments was 5 ± 3. Post-ablation imaging showed a technical success rate of 98 % (51 cases, 55 tumors). No major complications occurred. Follow-up imaging (26.2 ± 22.4 month) showed no local tumor progression or recurrence.

Use of the hepatobiliary phase for MRI-guided ablation of otherwise MR-occult tumors is a feasible approach for an effective and safe treatment of small HCC nodules.