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https://www.readbyqxmd.com/read/28541897/capacitive-micro-machined-ultrasound-transducers-for-interstitial-high-intensity-ultrasound-therapies
#1
W Apoutou N'Djin, Bjoern Gerold, Jeremy Vion, Michael Canney, An Nguyen-Dinh, Alexandre Carpentier, Jean-Yves Chapelon
Capacitive Micro-machined Ultrasound Transducers (CMUTs) exhibit several potential advantages over conventional piezo technologies for use in therapeutic ultrasound devices, including: ease of miniaturization and integration with electronics, broad bandwidth (>several MHz), and compatibility with magnetic resonance imaging (MRI). In this work, the electro-acoustic performance of CMUTs designed for interstitial high intensity contact ultrasound (HICU) applications was evaluated and the feasibility of generating ultrasound-induced heating and thermal destruction of biological tissues was studied...
May 24, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28540820/theoretical-model-for-laser-ablation-outcome-predictions-in-brain-calibration-and-validation-on-clinical-mr-thermometry-images
#2
Samuel John Fahrenholtz, Reza Madankan, Shabbar Danish, John D Hazle, R Jason Stafford, David Fuentes
PURPOSE: Neurosurgical laser ablation is experiencing a renaissance. Computational tools for ablation planning aim to further improve the intervention. Here, global optimisation and inverse problems are demonstrated to train a model that predicts maximum laser ablation extent. METHODS: A closed-form steady state model is trained on and then subsequently compared to N = 20 retrospective clinical MR thermometry datasets. Dice similarity coefficient (DSC) is calculated to provide a measure of region overlap between the 57 °C isotherms of the thermometry data and the model-predicted ablation regions; 57 °C is a tissue death surrogate at thermal steady state...
May 19, 2017: International Journal of Hyperthermia
https://www.readbyqxmd.com/read/28516051/evaluation-of-mr-thermometry-with-proton-resonance-frequency-method-at-7t
#3
Ping Wang
Quantitative and non-invasive temperature mapping using magnetic resonance imaging (MRI) provides a unique way to measure temperature evolution inside biological tissues. The method is widely used in thermal ablation procedures with magnetic fields at or below 3T. In this paper, the sensitivity of the MRI thermometry at 7T was studied using a proton resonance frequency (PRF)-based technique. We first used an agarose gel phantom with MR-compatible thermometry to calibrate the temperature coefficient, and then this temperature coefficient was employed to measure the internal temperature in both ex vivo (beef muscle) and in vivo (rat) experiments using focused ultrasound heating...
April 2017: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28513855/technical-note-system-for-evaluating-local-hypothermia-as-a-radioprotector-of-the-rectum-in-a-small-animal-model
#4
Brian A Hrycushko, Chenchen Bing, Cecil Futch, Michelle Wodzak, Strahinja Stojadinovic, Paul M Medin, Rajiv Chopra
PURPOSE: The protective effects of induced or even accidental hypothermia on the human body are widespread with several medical uses currently under active research. In vitro experiments using human cell lines have shown hypothermia provides a radioprotective effect that becomes more pronounced at large, single-fraction doses common to stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) treatments. This work describes the development of a system to evaluate local hypothermia for a radioprotive effect of the rat rectum during a large dose of radiation relevant to prostate SBRT...
May 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28415147/neurosurgical-laser-ablation-and-mr-thermometry-risks-of-multisite-workflow-pattern
#5
Paul S Larson, Sudhakar Vadivelu, Hooman Azmi-Ghadimi, Amy Nichols, Loretta Fauerbach, Helen Boehm Johnson
Neurosurgical laser ablation is a relatively new but rapidly growing application of stereotactic neurosurgery that allows neurosurgeons to treat many previously untreatable conditions with the added benefit of shorter hospitalizations and recovery times. The vast majority of these procedures, however, are performed using a multisite workflow pattern involving transport of the patient between the operating room (OR), the computed tomography (CT) suite, and the magnetic resonance imaging (MRI) suite, often necessitating patient transfer through public pathways and requiring multiple trips if laser fiber placement is not accurate...
April 2017: Journal of Healthcare Risk Management: the Journal of the American Society for Healthcare Risk Management
https://www.readbyqxmd.com/read/28413682/multi-focal-hifu-reduces-cavitation-in-mild-hyperthermia
#6
Vandiver Chaplin, Charles F Caskey
BACKGROUND: Mild-hyperthermia therapy (40-45 °C) with high-intensity focused ultrasound (HIFU) is a technique being considered in a number of different treatments such as thermally activated drug delivery, immune-stimulation, and as a chemotherapy adjuvant. Mechanical damage and loss of cell viability associated with HIFU-induced acoustic cavitation may pose a risk during these treatments or may hinder their success. Here we present a method that achieves mild heating and reduces cavitation by using a multi-focused HIFU beam...
2017: Journal of Therapeutic Ultrasound
https://www.readbyqxmd.com/read/28324929/hyperthermia-by-electromagnetic-fields-to-enhanced-clinical-results-in-oncology
#7
Gerard C van Rhoon, Maarten M Paulides, Jeannette M L van Holthe, Martine Franckena
Confining treatment to the tumor to improve therapeutic outcome and reduce toxicity, is a hot issue in cancer research. Hyperthermia is recognized as a strong sensitizer for radiotherapy and chemotherapy enhancing tumor control without increasing toxicity. Today's electromagnetic hyperthermia systems heat large tissue volumes with limited ability to selectively heat the tumor. Fortunately, tremendous improvements in 3-dimensional electromagnetic & temperature modelling provide an exciting opportunity to design advanced multi-element electromagnetic applicator systems...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28317125/referenceless-magnetic-resonance-temperature-imaging-using-gaussian-process-modeling
#8
Joshua P Yung, David Fuentes, Christopher J MacLellan, Florian Maier, Yannis Liapis, John D Hazle, R Jason Stafford
PURPOSE: During magnetic resonance (MR)-guided thermal therapies, water proton resonance frequency shift (PRFS) based MR temperature imaging can quantitatively monitor tissue temperature changes. It is widely known that the PRFS technique is easily perturbed by tissue motion, tissue susceptibility changes, magnetic field drift, and modality-dependent applicator induced artifacts. Here a referenceless Gaussian process modeling (GPM) based estimation of the PRFS is investigated as a methodology to mitigate unwanted background field changes...
March 20, 2017: Medical Physics
https://www.readbyqxmd.com/read/28237922/an-adaptive-non-local-means-filter-for-real-time-mr-thermometry
#9
Cornel Zachiu, Mario Ries, Chrit Moonen, Baudouin Denis de Senneville
Proton resonance frequency shift-based magnetic resonance thermometry is a currently used technique for monitoring temperature during targeted thermal therapies. However, in order to provide temperature updates with very short latency times, fast MR acquisition schemes are usually employed, which in turn might lead to noisy temperature measurements. This will, in general, have a direct impact on therapy control and endpoint detection. In this paper, we address this problem through an improved non-local filtering technique applied on the temperature images...
April 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28226512/hyperthermia-by-electromagnetic-fields-to-enhanced-clinical-results-in-oncology
#10
Gerard C van Rhoon, Maarten M Paulides, Jeannette M L van Holthe, Martine Franckena, Gerard C van Rhoon, Maarten M Paulides, Jeannette M L van Holthe, Martine Franckena, Maarten M Paulides, Martine Franckena, Gerard C van Rhoon, Jeannette M L van Holthe
Confining treatment to the tumor to improve therapeutic outcome and reduce toxicity, is a hot issue in cancer research. Hyperthermia is recognized as a strong sensitizer for radiotherapy and chemotherapy enhancing tumor control without increasing toxicity. Today's electromagnetic hyperthermia systems heat large tissue volumes with limited ability to selectively heat the tumor. Fortunately, tremendous improvements in 3-dimensional electromagnetic & temperature modelling provide an exciting opportunity to design advanced multi-element electromagnetic applicator systems...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28211622/mri-guided-focused-ultrasound-robotic-system-for-animal-experiments
#11
Marinos Yiannakou, Georgios Menikou, Christos Yiallouras, Cleanthis Ioannides, Christakis Damianou
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 0.4 MHz was used. The positioning device incorporates only MRI compatible materials...
February 17, 2017: International Journal of Medical Robotics + Computer Assisted Surgery: MRCAS
https://www.readbyqxmd.com/read/28188403/-stereotactic-laser-thermocoagulation-in-epilepsy-surgery
#12
C Hoppe, J-A Witt, C Helmstaedter, T Gasser, H Vatter, C E Elger
In common with other stereotactic procedures, stereotactic laser thermocoagulation (SLT) promises gentle destruction of pathological tissue, which might become especially relevant for epilepsy surgery in the future. Compared to standard resection, no large craniotomy is necessary, cortical damage during access to deep-seated lesions can be avoided and interventions close to eloquent brain areas become possible. We describe the history and rationale of laser neurosurgery as well as the two available SLT systems (Visualase® and NeuroBlate®; CE marks pending)...
February 10, 2017: Der Nervenarzt
https://www.readbyqxmd.com/read/28160227/assessment-of-brain-core-temperature-using-mr-dwi-thermometry-in-alzheimer-disease-patients-compared-to-healthy-subjects
#13
Gianvincenzo Sparacia, Koji Sakai, Kei Yamada, Giovanna Giordano, Rosalia Coppola, Massimo Midiri, Luigi Maria Grimaldi
PURPOSE: To assess the brain core temperature of Alzheimer disease (AD) patients in comparison with healthy volunteers using diffusion-weighted thermometry. MATERIALS AND METHODS: Fourteen AD patients (3 men, 11 women; age range 60-81 years, mean age 73.8 ± 6.1 years) and 14 healthy volunteers, age and sex-matched (mean age 70.1 ± 6.9 years; range 62-84 years; 5 men, 9 women) underwent MR examination between February 2014 and March 2016. MR imaging studies were performed with a 1...
February 3, 2017: Japanese Journal of Radiology
https://www.readbyqxmd.com/read/28143574/feasibility-of-real-time-mr-thermal-dose-mapping-for-predicting-radiofrequency-ablation-outcome-in-the-myocardium-in-vivo
#14
Solenn Toupin, Pierre Bour, Matthieu Lepetit-Coiffé, Valéry Ozenne, Baudouin Denis de Senneville, Rainer Schneider, Alexis Vaussy, Arnaud Chaumeil, Hubert Cochet, Frédéric Sacher, Pierre Jaïs, Bruno Quesson
BACKGROUND: Clinical treatment of cardiac arrhythmia by radiofrequency ablation (RFA) currently lacks quantitative and precise visualization of lesion formation in the myocardium during the procedure. This study aims at evaluating thermal dose (TD) imaging obtained from real-time magnetic resonance (MR) thermometry on the heart as a relevant indicator of the thermal lesion extent. METHODS: MR temperature mapping based on the Proton Resonance Frequency Shift (PRFS) method was performed at 1...
January 25, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/28126752/cerebral-temperature-dysregulation-mr-thermographic-monitoring-in-a-nonhuman-primate-study-of-acute-ischemic-stroke
#15
S Dehkharghani, C C Fleischer, D Qiu, M Yepes, F Tong
BACKGROUND AND PURPOSE: Cerebral thermoregulation remains poorly understood. Temperature dysregulation is deeply implicated in the potentiation of cerebrovascular ischemia. We present a multiphasic, MR thermographic study in a nonhuman primate model of MCA infarction, hypothesizing detectable brain temperature disturbances and brain-systemic temperature decoupling. MATERIALS AND METHODS: Three Rhesus Macaque nonhuman primates were sourced for 3-phase MR imaging: 1) baseline MR imaging, 2) 7-hour continuous MR imaging following minimally invasive, endovascular MCA stroke induction, and 3) poststroke day 1 MR imaging follow-up...
April 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28114116/combination-of-principal-component-analysis-and-optical-flow-motion-compensation-for-improved-cardiac-mr-thermometry
#16
S Toupin, B Denis de Senneville, V Ozenne, P Bour, M Lepetit-Coiffe, M Boissenin, P Jais, B Quesson
The use of magnetic resonance (MR) thermometry for the monitoring of thermal ablation is rapidly expanding. However, this technique remains challenging for the monitoring of the treatment of cardiac arrhythmia by radiofrequency ablation due to the heart displacement with respiration and contraction. Recent studies have addressed this problem by compensating in-plane motion in real-time with optical-flow based tracking technique. However, these algorithms are sensitive to local variation of signal intensity on magnitude images associated with tissue heating...
February 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28052042/a-printed-yagi-uda-antenna-for-application-in-magnetic-resonance-thermometry-guided-microwave-hyperthermia-applicators
#17
M M Paulides, R M C Mestrom, G Salim, B B Adela, W C M Numan, T Drizdal, D T B Yeo, A B Smolders
Biological studies and clinical trials show that addition of hyperthermia stimulates conventional cancer treatment modalities and significantly improves treatment outcome. This supra-additive stimulation can be optimized by adaptive hyperthermia to counteract strong and dynamic thermoregulation. The only clinically proven method for the 3D non-invasive temperature monitoring required is by magnetic resonance (MR) temperature imaging, but the currently available set of MR compatible hyperthermia applicators lack the degree of heat control required...
March 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28046739/su-f-j-225-histology-study-of-mr-guided-pulsed-focused-ultrasound-on-treatment-of-prostate-cancer-in-vivo
#18
L Chen, D Cvetkovic, X Chen, B Wang, R Gupta, C Ma
PURPOSE: Our previous study demonstrated significant tumor growth delay in the mice treated with pulsed high intensity focused ultrasound (pHIFU). The purpose of this study is to understand the cell killing mechanisms of pHIFU. METHODS: Prostate cancer cells (LNCaP), were grown orthotopically in 17 nude mice. Tumor-bearing mice were treated using pHIFU with an acoustic power of 25W, pulse width 100msec and 300 pulses in one sonication under MR guidance. Mutiple sonications were used to cover the whole tumor volume...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/27991449/accelerated-magnetic-resonance-thermometry-in-the-presence-of-uncertainties
#19
R Madankan, W Stefan, S J Fahrenholtz, C J MacLellan, J D Hazle, R J Stafford, J S Weinberg, G Rao, D Fuentes
A model-based information theoretic approach is presented to perform the task of magnetic resonance (MR) thermal image reconstruction from a limited number of observed samples on k-space. The key idea of the proposed approach is to optimally detect samples of k-space that are information-rich with respect to a model of the thermal data acquisition. These highly informative k-space samples can then be used to refine the mathematical model and efficiently reconstruct the image. The information theoretic reconstruction was demonstrated retrospectively in data acquired during MR-guided laser induced thermal therapy (MRgLITT) procedures...
January 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27973341/referenceless-mr-thermometry-a-comparison-of-five-methods
#20
Chao Zou, Changjun Tie, Min Pan, Qian Wan, Changhong Liang, Xin Liu, Yiu-Cho Chung
Proton resonance frequency shift (PRFS) MR thermometry is commonly used to measure temperature in thermotherapy. The method requires a baseline temperature map and is therefore motion sensitive. Several referenceless MR thermometry methods were proposed to address this problem but their performances have never been compared. This study compared the performance of five referenceless methods through simulation, heating of ex vivo tissues and in vivo imaging of the brain and liver of healthy volunteers. Mean, standard deviation, root mean square, 2/98 percentiles of error were used as performance metrics...
January 7, 2017: Physics in Medicine and Biology
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