Real-time lesion monitoring during FUS ablation using interleaved harmonic motion imaging guided FUS (Interleaved-HMIgFUS) in in vivo mouse and humans

Harmonic Motion Imaging (HMI) is a radiation-force-based ultrasound elasticity imaging technique that can be used to monitor FUS ablation by assessing ablation related changes in stiffness. HMI is advantageous as compared to other elasticity imaging methods in that it induces tissue displacement at a specified frequency, which enables isolation of FUS induced displacement. In conventional HMI, FUS is applied continuously without interruption, and bandstop filters are used to reduce FUS interference from the imaging data. In applications with high FUS pressure and highly heterogeneous tissues, frequency-based filtering methods may not be adequate for FUS interference removal. The purpose of this study was to demonstrate an interleaved-HMI guided FUS (HMIgFUS) sequence for real-time ablation monitoring, to maintain the advantages of single-frequency induced displacement with greater FUS noise reduction. Our method was performed in an in vivo breast cancer mouse model (n=5) and in one in vivo breast cancer patient. We also noted that the tumor of one mouse treated with FUS showed complete ablation and did not show recurrence, indicating preliminary evidence of FUS monotherapy in a triple-negative breast cancer mouse model.