Potential advantages of the MRI for the radiofrequency ablation of liver tumors

Purpose: To present first results of radiofrequency ablation of liver tumors using a new MR compatible applicator. Materials and Methods: We performed 37 interventions in 20 patients (mean age 58.6 years) with primary intrahepatic malignancies or metastases: colorectal carcinoma n = 6, hepatocellular carcinoma n = 3, pancreatic carcinoma n = 4, sarcoma n = 2, cholangio-cellular carcinoma n = 1, carcinoma of the tonsil n = 1, breast carcinoma n = 1, gastric carcinoma n = 1, and gastrointestinal stroma tumor n = 1. Interventions were performed under CT-guidance with CT fluoroscopy (n=32) and under MR-guidance (n=:5)) using fast T1-weighted sequences in breath-hold technique. RFA was performed with the RF-generator (150 W) under local anesthesia and sedation using MR compatible applicators (Starburst XL, Rita Medical Systems, USA) to-ether with the appropriate Soft Tissue Introducer System. Intra-interventional control was performed with intrahepauically or intralesionally placed introducer system or applicator. MR was performed with plain breath-triuuered T2-weighted turbo spin echo sequences (TSE T2) with fat saturation. Results: All interventions were performed without major events. The mean diameter of induced coagulation was 4.0 (+/-0.7) cm. Repositioning was necessary in 8 interventions (21 X) after detection of residual tumor on an intra-interventional MRI. After a mean follow-up of 6.5 (+/-1.2) Months, the local tumor control rate was 92%. Conclusion: MR-comparible RF applicators offer the opportunity for intra-interventional detection of residual tumor during RF ablations by use of sensitive MRI sequences. These procedures may lead to a higher confidence in tumour ablation and may reduce the number of re-interventions and local recurrences of intrahepatic tumors.