inter-Costal Liver Ablation Under Real-Time MR-Thermometry with Partial Activation of a HIFU Phased Array Transducer

Bruno Quesson¹, Mathilde Merle¹, Max Khler², Charles Mougenot³, Sebastien Roujol¹, Baudouin Denis de Senneville¹, Chrit T. Moonen¹

The partial obstruction of the High Intensity Focused Ultrasound beam by the rib cage complicates the treatment of liver tumors. A method for selective deactivation of the transducer elements located in front of the ribs (visualized on 3D anatomical MR images) is proposed. The effectiveness of the method for HIFU liver ablations is demonstrated ex vivo and in vivo in pigs during breathing with real-time, motion compensated, MR thermometry. No loss in heating efficacy was observed at the focal point and an important reduction of the heating in tissues surrounding the bones was obtained with deactivation of the transducer elements.