HIGH INTENSITY FOCUSED ULTRASOUND THERMAL LESION DETECTION USING LOCAL HARMONIC IMAGING

Supervisor: Dr. Jahan Tavakkoli

Local Harmonic Imaging (LHI) is an ultrasound-based method that can be used for the
detection of thermal lesions. This technique relies on the delivery of an acoustic radiation force to induce localized harmonic oscillations. In this study, it was hypothesized that the amplitude of oscillations for HIFU coagulated tissue is smaller than the amplitude of oscillations for normal tissue due to changes in the Young’s modulus. LHI amplitudes at three tissue stages were compared in porcine muscle (normal: 6.53 ± 0.68 μm, 2 minutes HIFU: 5.01 ± 0.88 μm, and 4 minutes HIFU: 2.96 ± 0.59 μm). The Young’s modulus at these tissue stages were 11.28 ± 1.57 kPa, 24.21 ± 2.66 kPa, and 40.38 ± 4.38 kPa, respectively. It was concluded that the decrease in the LHI amplitude is proportional to the increase in Young’s modulus. Additionally, a theoretical model that represents the LHI technique was developed and validated.