Journal of Therapeutic Ultrasound

BACKGROUND: Ultrasound therapies are promising, non-invasive applications with potential to significantly improve, e.g. cancer therapies like viro- or immunotherapy or surgical applications. However, a crucial step towards their breakthrough is still missing: affordable and easy-to-handle quality assurance tools for therapy devices and ways to verify treatment planning algorithms. This deficiency limits the safety and comparability of treatments. METHODS: To overcome this deficiency accurate spatial and temporal temperature maps could be used...

BACKGROUND: Current clinical protocols for MR-guided focused ultrasound (MRgFUS) treatment of osseous lesions, including painful bone metastases and osteoid osteomas, rely on measurement of the temperature change in adjacent muscle to estimate the temperature of the bone. The goal of this study was to determine if T2-based thermometry could be used to monitor the temperature change in bone marrow during focused ultrasound ablation of bone lesions. METHODS: We investigated the dependence of T2 on temperature in ex vivo bovine yellow bone marrow at 3T and studied the influence of acquisition parameters on the T2 measurements...

BACKGROUND: Uterine fibroids are the most common benign tumor in women, and surgical intervention is still the main fibroid treatment. Patient demands have encouraged development of less-invasive methods such as high-intensity focused ultrasound (HIFU). This study aimed to evaluate the safety and effectiveness of magnetic resonance-guided high-intensity focused ultrasound therapy using a volumetric ablation technique in the treatment of symptomatic uterine fibroids in China. METHODS: One hundred and seven patients were enrolled and treated with magnetic resonance-guided high-intensity focused ultrasound in this study...

BACKGROUND: Low-intensity pulsed ultrasound (LIPUS) has presented good results in the healing of chronic wounds. The objective of this study was to compare the effect of LIPUS on the viability of transverse rectus abdominal muscle (TRAM) flap in different regions (central and epigastric) in rats. METHODS: Twenty-one Wistar male rats were homogeneously distributed into three groups as follows: group 1 (control), animals submitted to surgery only; group 2, animals submitted to surgery and application of LIPUS at the center of the flap; and group 3, animals submitted to surgery and application of LIPUS at the flap area corresponding to the right inferior epigastric artery pedicle...

[This corrects the article DOI: 10.1186/s40349-016-0066-7.].

BACKGROUND: Low-intensity physiotherapeutic ultrasound has been used in physical therapy clinics; however, there remain some scientific issues regarding the bone-healing process. The objective of this study was to investigate the influence of low-intensity physiotherapeutic ultrasound on the initial stage of bone healing in rats. METHODS: Twenty-two male adult rats were assessed quantitatively and qualitatively using radiographic, biochemical, and histological analyses...

BACKGROUND: A major challenge in using magnetic resonance temperature imaging (MRTI) to monitor focused ultrasound (FUS) applications is achieving high spatio-temporal resolution over a large field of view (FOV). This is important to accurately monitor all ultrasound (US) power depositions. Magnetic resonance (MR) subsampling in conjunction with thermal model-based reconstruction of the MRTI utilizing Pennes bioheat transfer equation (PBTE) is one promising approach. The thermal properties used in the thermal model are often estimated from a pre-treatment, low-power sonication...

BACKGROUND: MR-guided focused ultrasound or high-intensity focused ultrasound (MRgFUS/MRgHIFU) is a non-invasive therapeutic modality with many potential applications in areas such as cancer therapy, drug delivery, and blood-brain barrier opening. However, the large financial costs involved in developing preclinical MRgFUS systems represent a barrier to research groups interested in developing new techniques and applications. We aim to mitigate these challenges by detailing a validated, open-source preclinical MRgFUS system capable of delivering thermal and mechanical FUS in a quantifiable and repeatable manner under real-time MRI guidance...

BACKGROUND: Skin function is dependent on its biomechanical characteristics, resistance, malleability, and elasticity. Therapeutic ultrasound may increase cutaneous malleability thus and optimize the rehabilitation process on specific diseases. The aim of this study is to evaluate possible alterations of biomechanical characteristics of the normal skin after therapeutic ultrasound application. METHODS: Thirty-one volunteers took part of the study, and the average age was 31...

BACKGROUND: Abdominal scars pose a challenge in magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) therapies, limiting patient selection and increasing the risk of skin burns. Especially, scars arising from longitudinal incisions are problematic as they usually lie medially at the lower abdomen where the ultrasound beam has to go through. Volumetric sonication has been shown to efficiently enlarge the ablated volume per sonication, but they nevertheless require more thermal energy to be deposited per sonication which increases the temperature in the near-field area located between the transducer and the target region...

BACKGROUND: Previous studies demonstrated both pre-clinically and clinically the feasibility of magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablations in the liver. To overcome the associated problem of respiratory motion of the ablation area, general anesthesia (GA) and mechanical ventilation was used in conjunction with either respiratory-gated energy delivery or energy delivery during induced apnea. However, clinical procedures requiring GA are generally associated with increased mortality, morbidity, and complication rate compared to procedural sedation and analgesia (PSA)...

Diagnostic ultrasound (DUS) pressures have the ability to induce inertial cavitation (IC) of systemically administered microbubbles; this bioeffect has many diagnostic and therapeutic implications in cardiovascular care. Diagnostically, commercially available lipid-encapsulated perfluorocarbons (LEP) can be utilized to improve endocardial and vascular border delineation as well as assess myocardial perfusion. Therapeutically, the liquid jets induced by IC can alter endothelial function and dissolve thrombi within the immediate vicinity of the cavitating microbubbles...

We present here biophysical models to gain deeper insights into how an acoustic stimulus might influence or modulate neuronal activity. There is clear evidence that neural activity is not only associated with electrical and chemical changes but that an electro-mechanical coupling is also involved. Currently, there is no theory that unifies the electrical, chemical, and mechanical aspects of neuronal activity. Here, we discuss biophysical models and hypotheses that can explain some of the mechanical aspects associated with neuronal activity: the soliton model, the neuronal intramembrane cavitation excitation model, and the flexoelectricity hypothesis...

Recent studies have demonstrated the effectiveness of magnetic resonance-guided focused ultrasound (MRgFUS) in the treatment of osteoid osteoma (OO), a painful, benign bone tumor. As MRgFUS is a noninvasive and radiation-free treatment, it stands to replace the current standard of care, percutaneous radiofrequency, or laser thermal ablation. Within an institution, creation of a clinical OO MRgFUS treatment program would not only provide cutting edge medical treatment at the current time but would also establish the foundation for an MRgFUS clinical service to introduce treatments currently under development into clinical practice in the future...

BACKGROUND: A noninvasive technique to monitor thermal lesion formation is necessary to ensure the accuracy and safety of high-intensity focused ultrasound (HIFU) treatment. The purpose of this study is to ultrasonically detect the tissue change due to thermal coagulation in the HIFU treatment enhanced by cavitation microbubbles. METHODS: An ultrasound imaging probe transmitted plane waves at a center frequency of 4.5 MHz. Ultrasonic radio-frequency (RF) echo signals during HIFU exposure at a frequency of 1...

BACKGROUND: MR-guided focused ultrasound (MRgFUS) might be a very safe and effective minimally invasive technique to treat facet joint pain caused by arthritis and other degenerative changes. However, there are still safety concerns for this treatment and challenges regarding MR imaging and temperature mapping due to susceptibility effects between the bone and soft tissue near the joint, which has resulted in poor MR image quality. The goal of this research was to evaluate multiple magnetic resonance imaging (MRI) pulse sequences for characterizing ablated lumbar facet joint lesions created by high-intensity focused ultrasound (FUS) and compare the findings to histological tissue assessment...

BACKGROUND: Bioheat models have been proposed to predict heat distribution in multilayered biological tissues after therapeutic ultrasound (TUS) stimulation. However, evidence on its therapeutic benefit is still controversial for many clinical conditions. The aim of this study was to evaluate and to compare the TUS heating distribution on commercially available bone phantoms and in vitro femur and tibia human samples, at 1 MHz and several ultrasonic pulse regimens, by means of a thermographic image processing technique...

BACKGROUND: Radiotherapy is a critical component of the multidisciplinary management of cancers of the head and neck. It may comprise the primary curative treatment modality or is used in an adjuvant setting to improve local control and survival by preventing seeding and reseeding of distant metastases from persistent reservoirs of locoregional disease. Although considerable advances have been made recently in the fields of radiotherapy, systemic treatment and surgery for head and neck tumours, locoregional recurrence rates remain high and treatment side effects may have severe impact on patients' quality of life...

BACKGROUND: The lesions induced by high-intensity focused ultrasound (HIFU) thermal ablations are particularly difficult to simulate due to the complexity of the involved phenomena. In particular, boiling has a strong influence on the lesion shape. Thus, it must be accounted for if it happens during the pulses to be modeled. However, no acoustic model enables the simulation of the resulting wave scattering. Therefore, we propose an equivalent model for the heat deposition pattern in the presence of boiling...

BACKGROUND: To improve understanding of shockwave therapy mechanisms, in vitro experiments are conducted and the correlation between cell reaction and shockwave parameters like the maximum pressure or energy density is studied. If the shockwave is not measured in the experimental setup used, it is usually assumed that the device's shockwave parameters (=manufacturer's free field measurements) are valid. But this applies only for in vitro setups which do not modify the shockwave, e.g., by reflection or refraction...