Agar-based Phantom for Evaluating Targeting of High-intensity Focused Ultrasound Systems for Breast Ablation.

Aim: Phantoms are often utilized for the preclinical evaluation of novel high-intensity focused ultrasound (HIFU) systems, serving as valuable tools for validating efficacy. In the present study, the feasibility of a homogeneous agar-based breast-shaped phantom as a tool for the preclinical evaluation of HIFU systems dedicated to breast cancer was assessed. Specifically, the effect of the increased phantom curvature on temperature increase was examined through sonications executed on two sides having varied curvatures.

Estimation of the Proton Resonance Frequency Coefficient in Agar-based Phantoms.

Aim: Agar-based phantoms are popular in high intensity focused ultrasound (HIFU) studies, with magnetic resonance imaging (MRI) preferred for guidance since it provides temperature monitoring by proton resonance frequency (PRF) shift magnetic resonance (MR) thermometry. MR thermometry monitoring depends on several factors, thus, herein, the PRF coefficient of agar phantoms was estimated.

Materials And Methods: Seven phantoms were developed with varied agar (2, 4, or 6% w/v) or constant agar (6% w/v) and varied silica concentrations (2, 4, 6, or 8% w/v) to assess the effect of the concentration on the PRF coefficient.

Advanced software for MRgFUS treatment planning.

Background And Objectives: Herein, a user-friendly software platform for 3-dimensional Focused Ultrasound treatment planning based on Magnetic Resonance Imaging (MRI) images is presented.

Methods: The software directly retrieves and loads MRI images. Various design tools can be used on the MRI images to define the treatment area and the sonication parameters.

Phantom-based assessment of motion and needle targeting accuracy of robotic devices for magnetic resonance imaging-guided needle biopsy.

Background: The current study proposes simple methods for assessing the performance of robotic devices intended for Magnetic Resonance Imaging (MRI)-guided needle biopsy.

Methods: In-house made agar-based breast phantoms containing biopsy targets served as the main tool in the evaluation process of an MRI compatible positioning device comprising a needle navigator. The motion accuracy of mechanical stages was assessed by calliper measurements.

Robotic system for magnetic resonance imaging-guided focused ultrasound treatment of thyroid nodules.

Background: Herein, a robotic system offering Magnetic Resonance-guided Focused Ultrasound (MRgFUS) therapy of thyroid nodules was developed.

Methods: The robotic system offers linear motion in 2 PC-controlled axes that navigate a 3 MHz single-element focused transducer. The system, through a C-arm structure attaches to the table of Magnetic Resonance Imaging (MRI) scanners and couples to the neck of patients lying in the supine position.

Characterization of a fat tissue mimicking material for high intensity focused ultrasound applications.

Purpose: Tissue-mimicking materials (TMMs) have a prominent role in validating new high intensity focused ultrasound (HIFU) therapies. Agar-based TMMs are often developed mimicking the thermal properties of muscle tissue, while TMMs simulating fat tissue properties are rarely developed. Herein, twelve agar-based TMMs were iteratively developed with varied concentrations of agar, water, glycerol and propan-2-ol, and characterized for their suitability in emulating the thermal conductivity of human fat tissue.

Ultrasonic attenuation of canine mammary tumours.

Background: Canine mammary tumours (CMTs) are the most common neoplasm appearing in female dogs and are considered the equivalent animal model of human breast cancer. However, in the literature, there is a gap for ultrasonic characterisation of these tumours. In this study, experimental measurements for acoustic attenuation and propagation speed of three surgically excised malignant CMTs were implemented.

Experimental evaluation of high intensity focused ultrasound for fat reduction of ex vivo porcine adipose tissue.

Purpose: The present study was stimulated by the continuous growth of commercially available high intensity focused ultrasound (HIFU) systems for fat reduction. Herein, HIFU was utilised for fat ablation using a single-element ultrasonic transducer operating in thermal mode.

Methods: The custom-made concave transducer that operates at 1.

Evaluation of ultrasonic scattering in agar-based phantoms using 3D printed scattering molds.

Purpose: Acoustic characterization of tissue mimicking materials in terms of attenuation, absorption, scattering and propagation velocity is essential for their utilisation in experiments, thus sparing the need for living tissues or cadavers. Although there is a vast literature regarding the acoustic characterization of such materials in terms of attenuation or propagation velocity, there is limited data regarding the quantification of the scattering coefficient. Herein stimulated the utilisation of four agar-based phantoms featuring different sizes of scattering agar-structures on one of their surfaces so as to provide experimental evaluation of the magnitude of scattering.

Experimental evaluation of the near-field and far-field heating of focused ultrasound using the thermal dose concept.

Background: Conventional motion algorithms utilized during High Intensity Focused Ultrasound (HIFU) procedures usually sonicate successive tissue cells, thereby inducing excess deposition of thermal dose in the pre-focal region. Long delays (~60 s) are used to reduce the heating around the focal region. In the present study the experimental evaluation of six motion algorithms so as to examine the required delay and algorithm for which the pre-focal (near-field) and post-focal (far-field) heating can be reduced using thermal dose estimations is presented.

Magnetic resonance image-guided focused ultrasound robotic system for transrectal prostate cancer therapy.

Background: A magnetic resonance image (MRI) guided robotic device for focussed ultrasound therapy of prostate cancer (PC) was developed. The device offers movement in 5 degrees of freedom (DOF) and uses a single-element transducer that operates at 3.2 MHz, has a diameter of 25 mm and focuses at 45 mm.