Phantom-based assessment of focused ultrasound thermal effects with conventional magnetic resonance imaging.

Background And Objective: This study presents key findings from Magnetic Resonance Imaging (MRI)-guided Focused Ultrasound (FUS) sonication experiments in a specialized gel phantom, aimed at demonstrating the effectiveness of using conventional T1-Weighted (T1-W) and T2-Weighted (T2-W) Turbo Spin Echo (TSE) sequences to assess FUS thermal effects and related system performance.

Methods: Three custom-manufactured, single-element spherically focused ultrasonic transducers were utilized in this study. The temporal regression of lesions induced by high-power FUS in the phantom model was investigated within a 3T MRI scanner for both employed sequences.

Focused Ultrasound Sonications of Tumor Model in Head Phantom under MRI Monitoring: Effect of Skull Obstruction on Focal Heating.

Purpose: This study presents the outcomes of a series of magnetic resonance imaging (MRI)-guided focused ultrasound (MRgFUS) sonications performed on an anatomically accurate head phantom with an embedded tumor simulator to evaluate the effectiveness of partial and complete tumor ablation with obstruction from thin polymer skull mimics.

Materials And Methods: The tumor simulator was subjected to single and grid sonications using a single-element concave transducer integrated with an MRI-compatible focused ultrasound (FUS) robotic system. All experiments were carried out in a high-field MRI scanner utilizing proton resonance frequency thermometry and T2-weighted (T2-W) turbo spin echo (TSE) imaging to evaluate the induced thermal effects.

Workflow of a Preclinical Robotic Magnetic Resonance Imaging-guided Focused Ultrasound Body System.

Background: Establishing an efficient workflow is crucial for the success of magnetic resonance-guided focused ultrasound (MRgFUS) procedures. The current study provides a comprehensive description of the workflow of a customized MRgFUS robotic body device for preclinical use and accompanied software through experiments in excised porcine tissue.

Methods: The employed system comprises a single-element spherically focused transducer of 2.

Magnetic Resonance Thermometry of Focused Ultrasound Using a Preclinical Focused Ultrasound Robotic System at 3T.

Aim: Focused ultrasound (FUS) therapies are often performed within magnetic resonance imaging (MRI) systems providing thermometry-based temperature monitoring. Herein, MRI thermometry was assessed for FUS sonications executed using a preclinical system on agar-based phantoms at 1.5T and 3T MRI scanners, using the proton resonance frequency shift technique.

Magnetic Resonance Imaging Monitoring of Thermal Lesions Produced by Focused Ultrasound.

Background: The main goal of the study was to find the magnetic resonance imaging (MRI) parameters that optimize contrast between tissue and thermal lesions produced by focused ultrasound (FUS) using T1-weighted (T1-W) and T2-weighted (T2-W) fast spin echo (FSE) sequences.

Methods: FUS sonications were performed in porcine tissue using a single-element FUS transducer of 2.6 MHz in 1.

Effect of Magnetic Resonance Imaging on the Motion Accuracy of Magnetic Resonance Imaging-compatible Focused Ultrasound Robotic System.

Purpose: The current study provides insights into the challenges of safely operating a magnetic resonance imaging (MRI)-guided focused ultrasound (MRgFUS) robotic system in a high-field MRI scanner in terms of robotic motion accuracy.

Materials And Methods: Grid sonications were carried out in phantoms and excised porcine tissue in a 3T MRI scanner using an existing MRgFUS robotic system. Fast low-angle shot-based magnetic resonance thermometry was employed for the intraprocedural monitoring of thermal distribution.

MRI compatibility testing of commercial high intensity focused ultrasound transducers.

Purpose: The study aimed to compare the performance of eight commercially available single-element High Intensity Focused Ultrasound (HIFU) transducers in terms of Magnetic Resonance Imaging (MRI) compatibility.

Methods: Imaging of an agar-based MRI phantom was performed in a 3 T MRI scanner utilizing T2-Weighted Fast Spin Echo (FSE) and Fast low angle shot (FLASH) sequences, which are typically employed for high resolution anatomical imaging and thermometry, respectively. Reference magnitude and phase images of the phantom were compared with images acquired in the presence of each transducer in terms of the signal to noise ratio (SNR), introduced artifacts, and overall image quality.

Tumor phantom model for MRI-guided focused ultrasound ablation studies.

Background: The persistent development of focused ultrasound (FUS) thermal therapy in the context of oncology creates the need for tissue-mimicking tumor phantom models for early-stage experimentation and evaluation of relevant systems and protocols.

Purpose: This study presents the development and evaluation of a tumor-bearing tissue phantom model for testing magnetic resonance imaging (MRI)-guided FUS (MRgFUS) ablation protocols and equipment based on MR thermometry.

Methods: Normal tissue was mimicked by a pure agar gel, while the tumor simulator was differentiated from the surrounding material by including silicon dioxide.

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.

Radiofrequency ablation for the treatment of a presumed enchondroma in the flat bones of the pelvis.

Herein, a 30-year-old Caucasian female who presented with a persistent pain in the right pelvic region due to an enchondroma and treated with RF ablation is described. An initial MRI of the pelvis revealed a well-circumscribed lesion in the right inferior ischiopubic ramus with a maximum diameter of 9.5 mm.

Challenges regarding MR compatibility of an MRgFUS robotic system.

Numerous challenges are faced when employing Magnetic Resonance guided Focused Ultrasound (MRgFUS) hardware in the Magnetic Resonance Imaging (MRI) setting. The current study aimed to provide insights on this topic through a series of experiments performed in the framework of evaluating the MRI compatibility of an MRgFUS robotic device. All experiments were performed in a 1.

MR relaxation times of agar-based tissue-mimicking phantoms.

Agar gels were previously proven capable of accurately replicating the acoustical and thermal properties of real tissue and widely used for the construction of tissue-mimicking phantoms (TMPs) for focused ultrasound (FUS) applications. Given the current popularity of magnetic resonance-guided FUS (MRgFUS), we have investigated the MR relaxation times T1 and T2 of different mixtures of agar-based phantoms. Nine TMPs were constructed containing agar as the gelling agent and various concentrations of silicon dioxide and evaporated milk.

Simple methods to test the accuracy of MRgFUS robotic systems.

Background: Robotic-assisted diagnostic and therapeutic modalities require a highly accurate performance to be certified for clinical application. In this paper, three simple methods for assessing the accuracy of motion of magnetic resonance-guided focused ultrasound (MRgFUS) robotic systems are presented.

Methods: The accuracy of motion of a 4 degrees of freedom robotic system intended for preclinical use of MRgFUS was evaluated by calliper-based and magnetic resonance imaging (MRI) methods, as well as visually by performing multiple ablations on a plastic film.

PET/CT imaging of prostate cancer in the era of small molecule prostate specific membrane antigen targeted tracers.

Staging and restaging of prostate cancer is crucial for treatment planning and prognosis. Accurate localization is of high relevance for a tailor-made therapy and an early detection of unknown metastatic spread can lead to a survival benefit. Evidence based guidelines that are currently in use were established using data from conventional imaging (such as magnetic resonance imaging (MRI), computed tomography (CT) and bone scintigraphy).

MRI-guided frameless biopsy robotic system with the inclusion of unfocused ultrasound transducer for brain cancer ablation.

Background: A magnetic resonance image (MRI) guided robotic system dedicated for brain biopsy was developed. The robotic system carries a biopsy needle and a small rectangular unfocused, single element, planar ultrasonic transducer which can be potentially utilized to ablate small and localized brain cancer.

Materials And Methods: The robotic device includes six computer-controlled axes.

Osteoid osteoma of the scaphoid bone associated with flexor carpi radialis calcific tendinitis and treated with CT-guided RF ablation.

Osteoid osteomas of the wrist are relatively rare and the diagnosis is challenging due to atypical clinical features. We describe a case of an osteoid osteoma of the scaphoid bone associated with calcific tendinitis of the adjacent flexor carpi radialis tendon and periarticular soft tissue calcifications in a 21-year-old man presenting with radial-sided wrist pain. The lesion was successfully treated with CT-guided RF ablation.

MRI-compatible breast/rib phantom for evaluating ultrasonic thermal exposures.

Introduction: The target of this study was the development of a magnetic resonance imaging (MRI) compatible breast phantom for focused ultrasound which includes plastic (ABS) ribs. The objective of the current study was the evaluation of a focused ultrasound procedure using the proposed phantom that eliminates rib heating.

Material And Methods: The proposed phantom was evaluated using two different focused ultrasound exposures.

MRI guided focused ultrasound robotic system for animal experiments.

Background: In this paper an MRI-guided focused ultrasound (MRgFUS) robotic system was developed that can be used for conducting experiments in small animals.The target for this robotic system regarding motion was to move a therapeutic ultrasound transducer in two Cartesian axes.

Methods: A single element spherically focused transducer of 3 cm diameter, focusing at 7 cm and operating at 0.

Spinal osteoid osteoma progressed to osteoblastoma with paraspinal soft tissue mass: a unique presentation.

Osteoid osteoma and osteoblastoma are rare benign bone-forming tumors with very similar histological features. They are nowadays considered as two distinct entities. Progression of an osteoid osteoma to osteoblastoma is considered very rare with only a few cases reported in the literature.

MRI-compatible bone phantom for evaluating ultrasonic thermal exposures.

Objective: The goal of the proposed study was the development of a magnetic resonance imaging (MRI) compatible bone phantom suitable for evaluating focused ultrasound protocols.

Materials And Methods: High resolution CT images were used to segment femur bone. The segmented model was manufactured with (Acrylonitrile Butadiene Styrene) ABS plastic using a 3-D printer.