Laser-induced thermotherapy (LITT)--evaluation of a miniaturised applicator and implementation in a 1.0-T high-field open MRI applying a porcine liver model.

ABSTRACT

OBJECTIVE: To evaluate the feasibility and safety of a novel LITT applicator for thermal ablation of liver malignancies in 1.0-T high-field open MRI. METHODS: A miniaturised 6-F double-tubed protective catheter with a closed cooling circuit was used with a flexible laser fibre, connected to a 1,064-nm NdYAG laser and evaluated in non-perfused porcine livers (18-30 W for 10-20 min, 2-W and 2-min increments; n = 210/applicator) in reference to an established 9-F system. As a proof of concept, MR-guided LITT was performed in two healthy domestic pigs in high-field open MRI. RESULTS: Ex-vivo, the coagulation volumes induced by the 6-F system with maximum applicable power of 24 W for 20 min (33.0 ± 4.4 cm(3)) did not differ significantly from those set with the 9-F system at 30 W for 20 min (35.8 ± 4.9 cm(3)) (p = 0.73). A flow-rate of 15 ml/min of the cooling saline solution was sufficient. MR navigation and thermometry were feasible. CONCLUSION: The miniaturised 6-F applicator can create comparable coagulation sizes to those of the 9-F system. Applicator guidance and online-thermometry in high-field open MRI are feasible.