T. Albrecht, B.B. Frericks, S. Valdeig, J. Ritz, K.J. Wolf; Berlin/DE

Purpose
To prospectively evaluate a new bi/multipolar radiofrequency ablation device in patients with hepatic malignancy regarding feasibility, ablation zone size and shape, technical effectiveness, complications and clinical out-come.

Material and methods
The device (Prosurge, Celon, Germany) used allows up to three bipolar probes to be placed within or closely around the tumour. No grounding pad is required and the electrical current runs between up to 6 electrodes with up to 15 possible electrode combinations within and closely around the tumour. 48 tumours (31 CRC metastases) in 30 patients were treated under guidance with CE-US or CE-CT, 36 lesions were ablated percutanously and 12 intraoperatively . Lesion size was calculated by 3D planimetry using dedicated software (Hepavision, Mevis, Germany) based on CE-MRI performed within 48h of ablation. Follow-up MRI was performed at three-monthly intervals during the first year and biannually thereafter (mean follow-up: 10 ± 9, range 1 – 31 months).

Results
Complete tumour destruction with a circumferential safety margin ≥ 5mm was achieved in 47 of 48 tumours (secondary effectiveness 98%). Ten tumours required re-ablation due to insufficient ablation zone size on post-interventional MRI (primary effectiveness 80%). Ablation zone volume (mean 55 40 ml) increased with number of probes and energy used. Maximum achievable diameters were 100 mm for percutaneous and 98 mm for intraoperative approach. 28 of 34 completely evaluable ablation zones were concentric, 3 moderately eccentric, 2 eccentric (due to incomplete fusion of individual ablation zones) and 1 wedge-shaped. One major complication (jejunal perforation) occurred. On follow-up, local recurrences occurred in 5 lesions (10%), 7 patients developed new metastases. 26 patients (87%) are currently alive, 20 (67%) of them tumour-free.

Conclusion
Multipolar radiofrequency of hepatic tumours achieves large ablation zones resulting in a high technical effectiveness and relatively low local recurrence rate.