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Mr thermometry

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https://www.readbyqxmd.com/read/28211622/mri-guided-focused-ultrasound-robotic-system-for-animal-experiments
#1
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
#2
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
#3
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
#4
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
#5
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...
January 26, 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
#6
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
#7
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
#8
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
#9
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
#10
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
https://www.readbyqxmd.com/read/27959970/magnetic-resonance-thermometry-guided-stereotactic-laser-ablation-of-cavernous-malformations-in-drug-resistant-epilepsy-imaging-and-clinical-results
#11
D Jay McCracken, Jon T Willie, Brad Fernald, Amit M Saindane, Daniel L Drane, Daniel L Barrow, Robert E Gross
BACKGROUND: Surgery is indicated for cerebral cavernous malformations (CCM) that cause medically refractory epilepsy. Real-time magnetic resonance thermography (MRT)-guided stereotactic laser ablation (SLA) is a minimally invasive approach to treating focal brain lesions. SLA of CCM has not previously been described. OBJECTIVE: To describe MRT-guided SLA, a novel approach to treating CCM-related epilepsy, with respect to feasibility, safety, imaging, and seizure control in 5 consecutive patients...
March 2016: Operative Neurosurgery (Hagerstown, Md.)
https://www.readbyqxmd.com/read/27882240/t2-based-temperature-monitoring-in-bone-marrow-for-mr-guided-focused-ultrasound
#12
Eugene Ozhinsky, Misung Han, Matthew Bucknor, Roland Krug, Viola Rieke
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...
2016: Journal of Therapeutic Ultrasound
https://www.readbyqxmd.com/read/27835808/evaluation-of-a-small-flat-rectangular-therapeutic-ultrasonic-transducer-intended-for-intravascular-use
#13
N Papadopoulos, G Menikou, M Yiannakou, C Yiallouras, K Ioannides, C Damianou
BACKGROUND: The aim of the proposed study was to evaluate the performance of a flat rectangular (2×10mm(2)) transducer operating at 4MHz. The intended application of this transducer is intravascular treatment of thrombosis and atherosclerosis. METHODS: The transducer's thermal capabilities were tested in two different gel phantoms. MR thermometry was used to demonstrate the thermal capabilities of this type of transducer. RESULTS: Temperature measurements demonstrated that this simple and small transducer adequately produced high temperatures, which can be utilized for therapeutic purposes...
February 2017: Ultrasonics
https://www.readbyqxmd.com/read/27759913/accurate-mr-thermometry-by-hyperpolarized-129-xe
#14
Le Zhang, Alex Burant, Andrew McCallister, Victor Zhao, Karl M Koshlap, Simone Degan, Michael Antonacci, Rosa Tamara Branca
PURPOSE: To investigate the temperature dependence of the resonance frequency of lipid-dissolved xenon (LDX) and to assess the accuracy of LDX-based MR thermometry. METHODS: The chemical shift temperature dependence of water protons, methylene protons, and LDX was measured from samples containing tissues with varying fat contents using a high-resolution NMR spectrometer. LDX results were then used to acquire relative and absolute temperature maps in vivo and the results were compared with PRF-based MR thermometry...
October 19, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27699844/specialized-volumetric-thermometry-for-improved-guidance-of-mrgfus-in-brain
#15
Michael Marx, Pejman Ghanouni, Kim Butts Pauly
PURPOSE: MR thermometry is critical for safe and effective transcranial focused ultrasound. The current single-slice MR thermometry sequence cannot achieve all desired treatment monitoring requirements. We propose an approach in which the imaging requirements of different aspects of treatment monitoring are met by optimizing multiple sequences. METHODS: Imaging requirements were determined for three stages of MR-guided focused ultrasound brain treatment: 1) focal spot localization, 2) focal spot monitoring, and 3) background monitoring...
October 4, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27690660/stereotactic-robot-assisted-mri-guided-laser-thermal-ablation-of-radiation-necrosis-in-the-posterior-cranial-fossa-technical-note
#16
Alvin Y Chan, Diem Kieu T Tran, Amandip S Gill, Frank P K Hsu, Sumeet Vadera
Laser interstitial thermal therapy (LITT) is a minimally invasive procedure used to treat a variety of intracranial lesions. Utilization of robotic assistance with stereotactic procedures has gained attention due to potential for advantages over conventional techniques. The authors report the first case in which robot-assisted MRI-guided LITT was used to treat radiation necrosis in the posterior fossa, specifically within the cerebellar peduncle. The use of a stereotactic robot allowed the surgeon to perform LITT using a trajectory that would be extremely difficult with conventional arc-based techniques...
October 2016: Neurosurgical Focus
https://www.readbyqxmd.com/read/27688881/mr-thermometry-for-focused-ultrasound-monitoring-utilizing-model-predictive-filtering-and-ultrasound-beam-modeling
#17
Henrik Odéen, Scott Almquist, Joshua de Bever, Douglas A Christensen, Dennis L Parker
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...
2016: Journal of Therapeutic Ultrasound
https://www.readbyqxmd.com/read/27687017/short-and-long-time-mr-signal-behavior-of-randomly-distributed-water-and-fat-numerical-simulations
#18
Mie K Lam, Chris J G Bakker, Chrit T W Moonen, Max A Viergever, Lambertus W Bartels
The MR time-signal behavior of water has been reported to be different on short and long time scales for systems of randomly distributed perturbers in water in the static dephasing regime. Up to now, the signal of the perturbers in such systems has not been taken into consideration. Water-fat emulsions are macroscopically homogeneous systems and can be considered as microscopically randomly distributed perturbing fat spheres embedded in water. In such water-fat systems, the signal of the perturber, fat, cannot be ignored...
September 30, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27597889/open-source-small-animal-magnetic-resonance-guided-focused-ultrasound-system
#19
Megan E Poorman, Vandiver L Chaplin, Ken Wilkens, Mary D Dockery, Todd D Giorgio, William A Grissom, Charles F Caskey
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...
2016: Journal of Therapeutic Ultrasound
https://www.readbyqxmd.com/read/27552745/kalman-filtered-bio-heat-transfer-model-based-self-adaptive-hybrid-magnetic-resonance-thermometry
#20
Yuxin Zhang, Shuo Chen, Kexin Deng, Bingyao Chen, Xing Wei, Jiafei Yang, Shi Wang, Kui Ying
To develop a self-adaptive and fast thermometry method by combining the original hybrid magnetic resonance thermometry method and the bio heat transfer equation (BHTE) model. The proposed Kalman filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry, abbreviated as KalBHT hybrid method, introduced the BHTE model to synthesize a window on the regularization term of the hybrid algorithm, which leads to a self-adaptive regularization both spatially and temporally with change of temperature...
January 2017: IEEE Transactions on Medical Imaging
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