Mechanical fractionation of tissues using microsecond-long HIFU pulses on a clinical MR-HIFU system

AbstractPurpose: High intensity focussed ultrasound (HIFU) can non-invasively treat tumours with minimal or no damage to intervening tissues. While continuous-wave HIFU thermally ablates target tissue, the effect of hundreds of microsecond-long pulsed sonicationsis examined in this work. The objective of this study was to characterise sonicationparameter-dependent thermomechanical bioeffects to provide the foundation for future preclinical studies and facilitate clinical translation.Methods and materials: Acoustic power, numberof cycles/pulse, sonicationtime and pulse repetition frequency(PRF) were varied on a clinical magnetic resonance imaging (MRI)-guided HIFU (MR-HIFU) system. Ex vivo porcine liver, kidney and cardiac muscletissue samples were sonicated(3 × 3 grid pattern, 1 mm spacing). Temperature, thermal dose and T2 relaxation times were quantified using MRI. Lesions were histologically analysed using H&E and vimentin stains for lesion structure and viability.Results: Thermomechanical HIFU ...