title: Use of semiflexible applicators for radiofrequency ablation of liver tumors.
abstract: OBJECTIVE
  To evaluate the feasibility and potential advantages of the radiofrequency ablation of liver tumors using new MRI-compatible semiflexible applicators in a closed-bore high-field MRI scanner.
  
  
  METHODS
  We treated 8 patients with 12 malignant liver tumors of different origin (5 colorectal carcinoma, 2 cholangiocellular carcinoma, 1 breast cancer) under MRI guidance. Radiofrequency ablation (RFA) was performed using 5 cm Rita Starburst Semi-Flex applicators (Rita Medical Systems, Milwaukee, WI, USA) which are suitable for MR- and CT-guided interventions and a 150 W RF generator. All interventions were performed in a closed-bore 1.5 T high-field MRI scanner for MRI-guided RFA using fast T1-weighted gradient echo sequences and T2-weighted ultra-turbo spin echo sequences. Control and follow-up MRI examinations were performed on the next day, at 6 weeks, and every 3 months after RFA. Control MRI were performed as double-contrast MRI examinations (enhancement with iron oxide and gadopentetate dimeglumine). All interventions were performed with the patient under local anesthesia and analgo-sedation.
  
  
  RESULTS
  The mean diameter of the treated hepatic tumors was 2.4 cm (+/-0.6 cm, range 1.0-3.2 cm). The mean diameter of induced necrosis was 3.1 cm (+/-0.4 cm). We achieved complete ablation in all patients. Follow-up examinations over a duration of 7 months (+/-1.3 months, range 4-9 month) showed a local control rate of 100% in this group of patients. All interventions were performed without major complications; only 2 subcapsular hematomas were documented.
  
  
  CONCLUSIONS
  RFA of liver tumors using semiflexible applicators in closed-bore 1.5 T scanner systems is feasible. These applicators might simplify the RFA of liver tumors under MRI control. The stiff distal part of the applicator facilitates its repositioning.
authors.affiliation: Klinik für Strahlenheilkunde und Poliklinik, Charite, Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353, Berlin, Germany. gunnar.gaffke@charite.de
authors.forename: G
authors.initials: G
authors.lastname: Gaffke
authors.forename: B
authors.initials: B
authors.lastname: Gebauer
authors.forename: F D
authors.initials: FD
authors.lastname: Knollmann
authors.forename: T
authors.initials: T
authors.lastname: Helmberger
authors.forename: J
authors.initials: J
authors.lastname: Ricke
authors.forename: H
authors.initials: H
authors.lastname: Oettle
authors.forename: R
authors.initials: R
authors.lastname: Felix
authors.forename: C
authors.initials: C
authors.lastname: Stroszczynski
mesh_terms: D000368:Aged; D017115:Catheter Ablation; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media