keyword
MENU ▼
Read by QxMD icon Read
search

Mr thermometry

keyword
https://www.readbyqxmd.com/read/29774894/value-of-diffusion-weighted-imaging-for-monitoring-tissue-change-during-magnetic-resonance-guided-high-intensity-focused-ultrasound-therapy-in-bone-applications-an-ex-vivo-study
#1
Sharon L Giles, Jessica M Winfield, David J Collins, Ian Rivens, John Civale, Gail R Ter Haar, Nandita M deSouza
Background: Magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU) can palliate metastatic bone pain by periosteal neurolysis. We investigated the value of diffusion-weighted imaging (DWI) for monitoring soft tissue changes adjacent to bone during MR-guided HIFU. We evaluated the repeatability of the apparent diffusion coefficient (ADC) measurement, the temporal evolution of ADC change after sonication, and its relationship with thermal parameters. Methods: Ex-vivo experiments in lamb legs ( n = 8) were performed on a Sonalleve MR-guided HIFU system...
2018: European radiology experimental
https://www.readbyqxmd.com/read/29764258/reference-less-mr-thermometry-on-pre-clinical-thiel-human-cadaver-for-liver-surgery-with-mrgfus
#2
Ioannis Karakitsios, Senay Mihcin, Andreas Melzer
PURPOSE: Reference-less MR thermometry can be a promising technique for temperature mapping during liver treatment with Magnetic Resonance-guided Focused Ultrasound (MRgFUS), as it is more robust to breathing motion than Proton Resonance Frequency MR thermometry. However, there is a lack of a pre-clinical model for repeatable testing of reference-less thermometry. The purpose of this work was to verify the explanted Thiel embalmed human liver and whole Thiel embalmed human cadaver for application of a custom made reference-less thermometry algorithm during MRgFUS sonication...
May 15, 2018: Minimally Invasive Therapy & Allied Technologies: MITAT
https://www.readbyqxmd.com/read/29607551/high-peak-and-high-average-radiofrequency-power-transmit-receive-switch-for-thermal-magnetic-resonance
#3
Yiyi Ji, Werner Hoffmann, Michal Pham, Alexander E Dunn, Haopeng Han, Celal Özerdem, Helmar Waiczies, Michael Rohloff, Beate Endemann, Cyrille Boyer, May Lim, Thoralf Niendorf, Lukas Winter
PURPOSE: To study the role of temperature in biological systems, diagnostic contrasts and thermal therapies, RF pulses for MR spin excitation can be deliberately used to apply a thermal stimulus. This application requires dedicated transmit/receive (Tx/Rx) switches that support high peak powers for MRI and high average powers for RF heating. To meet this goal, we propose a high-performance Tx/Rx switch based on positive-intrinsic-negative diodes and quarter-wavelength (λ/4) stubs. METHODS: The λ/4 stubs in the proposed Tx/Rx switch design route the transmitted RF signal directly to the RF coil/antenna without passing through any electronic components (e...
April 1, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29556899/brain-core-temperature-of-patients-before-and-after-orthotopic-liver-transplantation-assessed-by-dwi-thermometry
#4
Gianvincenzo Sparacia, Roberto Cannella, Vincenzina Lo Re, Giuseppe Mamone, Koji Sakai, Kei Yamada, Roberto Miraglia
PURPOSE: To assess brain-core temperature of end-stage liver disease patients undergoing orthotopic liver transplantation (OLT) using a temperature measurement technique based on the apparent diffusion coefficient of the cerebrospinal fluid in the lateral ventricles. MATERIALS AND METHODS: The study group was composed of 19 patients with a model for end-stage liver disease (MELD) score of 23.7 who underwent MR imaging before and after OLT. MR imaging studies were performed with a 1...
May 2018: Japanese Journal of Radiology
https://www.readbyqxmd.com/read/29498102/a-simple-head-sized-phantom-for-realistic-static-and-radiofrequency-characterization-at-high-fields
#5
Wyger M Brink, Zhiyi Wu, Andrew G Webb
PURPOSE: To demonstrate a simple head-sized phantom for realistic static and RF field characterization in high field systems. METHODS: The head-sized phantom was composed of an ellipsoidal compartment and a spherical cavity to mimic the nasal cavity. The phantom was filled with an aqueous solution of polyvinylpyrrolidone (PVP), to mimic the average dielectric properties of brain tissue. The static and RF field distributions were characterized on a 7T MRI system and compared to in vivo measurements and simulations...
March 1, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29409819/referenced-mr-thermometry-using-three-echo-phase-based-fat-water-separation-method
#6
Lorne W Hofstetter, Desmond T B Yeo, W Thomas Dixon, Luca Marinelli, Thomas K Foo
A three-point image reconstruction method for internally referenced MR thermometry was developed. The technique exploits the fact that temperature-induced changes in the water resonance frequency are small relative to the chemical shift difference between water and fat signals. This property enabled the use of small angle approximations to derive an analytic phase-based fat-water separation method for MR thermometry. Ethylene glycol and cream cool-down experiments were performed to validate measurement technique...
February 2, 2018: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/29406409/enabling-technology-for-mri-guided-intervention
#7
Farzad Sedaghat, Kemal Tuncali
The use of magnetic resonance imaging (MRI) for image-guided intervention poses both great opportunity and challenges. Although MRI is distinguished by its excellent contrast resolution and lack of ionizing radiation, it was not till the 1990s that technologic innovations allowed for adoption of MRI as a guidance modality for intervention. With advances in magnet, protocol, coil, biopsy needle, and ablation probe design, MRI has emerged as a viable, and increasingly, preferable alternative to other image guidance modalities...
February 2018: Topics in Magnetic Resonance Imaging: TMRI
https://www.readbyqxmd.com/read/29385919/focused-ultrasound-in-neurosurgery-a-historical-perspective
#8
Maya Harary, David J Segar, Kevin T Huang, Ian J Tafel, Pablo A Valdes, G Rees Cosgrove
Focused ultrasound (FUS) has been under investigation for neurosurgical applications since the 1940s. Early experiments demonstrated ultrasound as an effective tool for the creation of intracranial lesions; however, they were limited by the need for craniotomy to avoid trajectory damage and wave distortion by the skull, and they also lacked effective techniques for monitoring. Since then, the development and hemispheric distribution of phased arrays has resolved the issue of the skull and allowed for a completely transcranial procedure...
February 2018: Neurosurgical Focus
https://www.readbyqxmd.com/read/29378441/real-time-3d-ultrasound-based-motion-tracking-for-the-treatment-of-mobile-organs-with-mr-guided-high-intensity-focused-ultrasound
#9
Pierre Bour, Valéry Ozenne, Fabrice Marquet, Baudouin Denis de Senneville, Erik Dumont, Bruno Quesson
INTRODUCTION: Magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) treatments of mobile organs require locking the HIFU beam on the targeted tissue to maximise heating efficiency. We propose to use a standalone 3 D ultrasound (US)-based motion correction technique using the HIFU transducer in pulse-echo mode. Validation of the method was performed in vitro and in vivo in the liver of pig under MR-thermometry. METHODS: 3 D-motion estimation was implemented using ultrasonic speckle-tracking between consecutive acquisitions...
February 21, 2018: International Journal of Hyperthermia
https://www.readbyqxmd.com/read/29301453/evaluation-and-selection-of-anatomic-sites-for-magnetic-resonance-imaging-guided-mild-hyperthermia-therapy-a-healthy-volunteer-study
#10
Satya V V N Kothapalli, Michael B Altman, Lifei Zhu, Ari Partanen, Galen Cheng, H Michael Gach, William Straube, Imran Zoberi, Dennis E Hallahan, Hong Chen
PURPOSE: Since mild hyperthermia therapy (MHT) requires maintaining the temperature within a narrow window (e.g. 40-43 °C) for an extended duration (up to 1 h), accurate and precise temperature measurements are essential for ensuring safe and effective treatment. This study evaluated the precision and accuracy of MR thermometry in healthy volunteers at different anatomical sites for long scan times. METHODS: A proton resonance frequency shift method was used for MR thermometry...
January 4, 2018: International Journal of Hyperthermia
https://www.readbyqxmd.com/read/29215150/mri-monitoring-of-focused-ultrasound-sonications-near-metallic-hardware
#11
Hans Weber, Pejman Ghanouni, Aurea Pascal-Tenorio, Kim Butts Pauly, Brian A Hargreaves
PURPOSE: To explore the temperature-induced signal change in two-dimensional multi-spectral imaging (2DMSI) for fast thermometry near metallic hardware to enable MR-guided focused ultrasound surgery (MRgFUS) in patients with implanted metallic hardware. METHOD: 2DMSI was optimized for temperature sensitivity and applied to monitor focus ultrasound surgery (FUS) sonications near metallic hardware in phantoms and ex vivo porcine muscle tissue. Further, we evaluated its temperature sensitivity for in vivo muscle in patients without metallic hardware...
July 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29193144/simulating-thermal-effects-of-mr-guided-focused-ultrasound-in-cortical-bone-and-its-surrounding-tissue
#12
Thomas J Hudson, Thomas Looi, Samuel Pichardo, Joao Amaral, Michael Temple, James M Drake, Adam C Waspe
PURPOSE: Magnetic resonance-guided focused ultrasound (MRgFUS) is emerging as a treatment alternative for osteoid osteoma and painful bone metastases. This study describes a new simulation platform that predicts the distribution of heat generated by MRgFUS when applied to bone tissue. METHODS: Calculation of the temperature distribution was performed using two mathematical models. The first determined the propagation and absorption of acoustic energy through each medium, and this was performed using a multilayered approximation of the Rayleigh integral method...
February 2018: Medical Physics
https://www.readbyqxmd.com/read/29115692/a-spiral-based-volumetric-acquisition-for-mr-temperature-imaging
#13
Samuel W Fielden, Xue Feng, Li Zhao, G Wilson Miller, Matthew Geeslin, Robert F Dallapiazza, W Jeffrey Elias, Max Wintermark, Kim Butts Pauly, Craig H Meyer
PURPOSE: To develop a rapid pulse sequence for volumetric MR thermometry. METHODS: Simulations were carried out to assess temperature deviation, focal spot distortion/blurring, and focal spot shift across a range of readout durations and maximum temperatures for Cartesian, spiral-out, and retraced spiral-in/out (RIO) trajectories. The RIO trajectory was applied for stack-of-spirals 3D imaging on a real-time imaging platform and preliminary evaluation was carried out compared to a standard 2D sequence in vivo using a swine brain model, comparing maximum and mean temperatures measured between the two methods, as well as the temporal standard deviation measured by the two methods...
June 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29017073/noninvasive-detection-of-focal-brain-hyperthermia-related-to-continuous-epileptic-activities-using-proton-mr-spectroscopy
#14
Daichi Sone, Naoki Ikegaya, Akio Takahashi, Kaoru Sumida, Miho Ota, Takashi Saito, Yukio Kimura, Hiroshi Matsuda, Noriko Sato
Recent studies using rat models suggested that epileptic discharges (EDs) can induce focal brain hyperthermia, but such ED-related hyperthermia has not been confirmed in humans. We examined hyperthermia of the focus of epilepsy using noninvasive proton magnetic resonance spectroscopy ((1)H-MRS) thermometry. We recruited six pediatric patients with refractory daily seizures, continuous interictal epileptic discharges, and concordant focus lesions on MRI who had undergone comprehensive presurgical exams. (1)H-MRS thermometry calculated the temperatures of the presumed epileptogenic lesions, and we examined the contralateral counterparts in each patient as controls...
October 6, 2017: Epilepsy Research
https://www.readbyqxmd.com/read/28944490/hybrid-ultrasound-mr-guided-hifu-treatment-method-with-3d-motion-compensation
#15
Zarko Celicanin, Gibran Manasseh, Lorena Petrusca, Klaus Scheffler, Vincent Auboiroux, Lindsey A Crowe, Jean-Noel Hyacinthe, Yutaka Natsuaki, Francesco Santini, Christoph D Becker, Sylvain Terraz, Oliver Bieri, Rares Salomir
PURPOSE: Treatments using high-intensity focused ultrasound (HIFU) in the abdominal region remain challenging as a result of respiratory organ motion. A novel method is described here to achieve 3D motion-compensated ultrasound (US) MR-guided HIFU therapy using simultaneous ultrasound and MRI. METHODS: A truly hybrid US-MR-guided HIFU method was used to plan and control the treatment. Two-dimensional ultrasound was used in real time to enable tracking of the motion in the coronal plane, whereas an MR pencil-beam navigator was used to detect anterior-posterior motion...
May 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28935624/the-brain-thermal-response-as-a-potential-neuroimaging-biomarker-of-cerebrovascular-impairment
#16
C C Fleischer, J Wu, D Qiu, S-E Park, F Nahab, S Dehkharghani
BACKGROUND AND PURPOSE: Brain temperature is critical for homeostasis, relating intimately to cerebral perfusion and metabolism. Cerebral thermometry is historically challenged by the cost and invasiveness of clinical and laboratory methodologies. We propose the use of noninvasive MR thermometry in patients with cerebrovascular disease, hypothesizing the presence of a measurable brain thermal response reflecting the tissue hemodynamic state. MATERIALS AND METHODS: Contemporaneous imaging and MR thermometry were performed in 10 patients (32-68 years of age) undergoing acetazolamide challenge for chronic, anterior circulation steno-occlusive disease...
November 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28922117/magnetic-resonance-mediated-radiofrequency-ablation
#17
Yik-Kiong Hue, Alexander R Guimaraes, Ouri Cohen, Erez Nevo, Abraham Roth, Jerome L Ackerman
To introduce magnetic resonance mediated radiofrequency ablation (MR-RFA), in which the MRI scanner uniquely serves both diagnostic and therapeutic roles. In MR-RFA scanner-induced RF heating is channeled to the ablation site via a Larmor frequency RF pickup device and needle system, and controlled via the pulse sequence. MR-RFA was evaluated with simulation of electric and magnetic fields to predict the increase in local specific-absorption-rate (SAR). Temperature-time profiles were measured for different configurations of the device in agar phantoms and ex vivo bovine liver in a 1...
February 2018: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28812002/image-guided-thermal-ablation-with-mr-based-thermometry
#18
REVIEW
Mingming Zhu, Ziqi Sun, Chin K Ng
Thermal ablation techniques such as radiofrequency, microwave, high intensity focused ultrasound (HIFU) and laser have been used as minimally invasive strategies for the treatment of variety of cancers. MR thermometry methods are readily available for monitoring thermal distribution and deposition in real time, leading to decrease of incidents of normal tissue damage around targeted lesion. HIFU and laser-induced thermal therapy (LITT) are the two widely accepted tumor ablation techniques because of their compatibility with MR systems...
June 2017: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28795419/simultaneous-mr-thermometry-and-acoustic-radiation-force-imaging-using-interleaved-acquisition
#19
Joshua T de Bever, Henrik Odéen, Lorne W Hofstetter, Dennis L Parker
PURPOSE: A novel and practical method for simultaneously performing MR acoustic radiation force imaging (ARFI) and proton resonance frequency (PRF)-shift thermometry has been developed and tested. This could be an important tool for evaluating the success of MR-guided focused ultrasound procedures for which MR-thermometry measures temperature and thermal dose and MR-ARFI detects changes in tissue mechanical properties. METHODS: MR imaging was performed using a gradient recalled echo segmented echo-planar imaging pulse sequence with bipolar motion encoding gradients (MEG)...
March 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28748092/a-focused-ultrasound-treatment-system-for-moving-targets-part-i-generic-system-design-and-in-silico-first-stage-evaluation
#20
Michael Schwenke, Jan Strehlow, Daniel Demedts, Sabrina Haase, Diego Barrios Romero, Sven Rothlübbers, Caroline von Dresky, Stephan Zidowitz, Joachim Georgii, Senay Mihcin, Mario Bezzi, Christine Tanner, Giora Sat, Yoav Levy, Jürgen Jenne, Matthias Günther, Andreas Melzer, Tobias Preusser
BACKGROUND: Focused ultrasound (FUS) is entering clinical routine as a treatment option. Currently, no clinically available FUS treatment system features automated respiratory motion compensation. The required quality standards make developing such a system challenging. METHODS: A novel FUS treatment system with motion compensation is described, developed with the goal of clinical use. The system comprises a clinically available MR device and FUS transducer system...
2017: Journal of Therapeutic Ultrasound
keyword
keyword
32174
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"