MR thermometry characterization of a hyperthermia ultrasound array designed using the k-space computational method

Area of Science:

• Medical Physics
• Biomedical Engineering

Background:

• Ultrasound-induced hyperthermia is an effective adjuvant therapy for prostate cancer when a uniform thermal dose is achieved.
• Accurate ultrasound phased array design and thermometry are crucial for effective hyperthermia treatment.
• 3D prostate models and computational methods aid in designing effective hyperthermia phased arrays.

Purpose of the Study:

• To design an intracavitary ultrasound probe for prostate cancer hyperthermia using a 3D prostate model and the k-space computational method.
• To evaluate the designed probe's performance using ex vivo and in vivo hyperthermia experiments with noninvasive MRI thermometry.

Main Methods:

• A 3D acoustical prostate model was created from Visible Human Project data.
• The k-space computational method simulated the phased array's pressure wavefield using the linear acoustic wave equation.
• A 4x20 element phased array probe was constructed and evaluated using noninvasive MRI thermometry and a feedback controller.

Main Results:

• K-space simulations and exposimetry showed agreement within 9%.
• Ex vivo and in vivo experiments achieved target steady-state temperatures of 42.9 ± 0.38°C and 43.1 ± 0.80°C, respectively.
• The probe and feedback controller demonstrated effective hyperthermia delivery.

Conclusions:

• The k-space method is a powerful tool for predicting pressure wavefields in large-scale, 3D, inhomogeneous tissue models.
• Noninvasive MRI thermometry validated the probe's efficacy and the feedback controller's performance.
• The developed probe and method show promise for in vivo hyperthermia treatment of canine prostate cancer.