MR-guided Microwave Ablation in Hepatic Tumours: Initial Results in Clinical Routine

Objectives: Evaluation of the technical success, patient safety and technical effectiveness of magnetic resonance (MR)-guided microwave ablation of hepatic malignancies.

Methods: Institutional review board approval and informed patient consent were obtained. Fifteen patients (59.8 years ± 9.5) with 18 hepatic malignancies (7 hepatocellular carcinomas, 11 metastases) underwent MR-guided microwave ablation using a 1.5-T MR system. Mean tumour size was 15.4 mm ± 7.7 (7-37 mm). Technical success and ablation zone diameters were assessed by post-ablative MR imaging. Technique effectiveness was assessed after 1 month. Complications were classified according to the Common Terminology Criteria for Adverse Events (CTCAE). Mean follow-up was 5.8 months ± 2.6 (1-10 months).

Results: Technical success and technique effectiveness were achieved in all lesions. Lesions were treated using 2.5 ± 1.2 applicator positions. Mean energy and ablation duration per tumour were 37.6 kJ ± 21.7 (9-87 kJ) and 24.7 min ± 11.1 (7-49 min), respectively. Coagulation zone short- and long-axis diameters were 31.5 mm ± 10.5 (16-65 mm) and 52.7 mm ± 15.4 (27-94 mm), respectively. Two CTCAE-2-complications occurred (pneumothorax, pleural effusion). Seven patients developed new tumour manifestations in the untreated liver. Local tumour progression was not observed.

Conclusions: Microwave ablation is feasible under near real-time MR guidance and provides effective treatment of hepatic malignancies in one session.

Key Points: • Planning, applicator placement and therapy monitoring are possible without using contrast enhancement • Energy transmission from the generator to the scanner room is safely possible • MR-guided microwave ablation provides effective treatment of hepatic malignancies in one session • Therapy monitoring is possible without applicator retraction from the ablation site.