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El Sabbagh N, Chassain C, Ratiney H, Pagés G, Bonny JM. Spurious phase correction in rapid metabolic imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 332:107065. [PMID: 34560390 DOI: 10.1016/j.jmr.2021.107065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/06/2021] [Accepted: 09/06/2021] [Indexed: 06/13/2023]
Abstract
IDEAL-type magnetic resonance spectroscopic imaging (MRSI) sequences require the acquisition of several datasets using optimized sampling in the time domain to reconstruct metabolite maps. Each unitary scan consists of a selective slice (2D) or slab (3D) excitation followed by an evolution time and then the acquisition of the spatially encoded signal. It is critical that the phase variation during the evolution time for each scan is only dependent on chemical shifts. In this paper, we described the apparition of spurious phase due to either the transmit or the receive frequency. The presence of this unwanted phase depends on (i) where the commutation between these two frequencies is performed and (ii) how it is done, as there are two phase commutation modes: continuous and coherent. We present the correction needed in function of the different cases. It appears that some solutions are universal. However, it is critical to know which case is implemented on the MRI scanner, which is not always easy information to have. We illustrated several cases with our preclinical MRI by using the IDEAL spiral method on a 13C phantom.
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Affiliation(s)
- Nour El Sabbagh
- INRAE, UR QuaPA, F-63122 Saint-Gènes-Champanelle, France; INRAE, AgroResonance Facility, F-63122 Saint-Genès-Champanelle, France; Université Clermont Auvergne, CHU, CNRS, Clermont Auvergne INP, Institut Pascal, F-63000 Clermont-Ferrand, France.
| | - Carine Chassain
- INRAE, UR QuaPA, F-63122 Saint-Gènes-Champanelle, France; INRAE, AgroResonance Facility, F-63122 Saint-Genès-Champanelle, France; Université Clermont Auvergne, CHU, CNRS, Clermont Auvergne INP, Institut Pascal, F-63000 Clermont-Ferrand, France
| | - Hélène Ratiney
- Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM Saint Etienne, CNRS, Inserm, CREATIS UMR5220, U1294, F-69621, LYON, France
| | - Guilhem Pagés
- INRAE, UR QuaPA, F-63122 Saint-Gènes-Champanelle, France; INRAE, AgroResonance Facility, F-63122 Saint-Genès-Champanelle, France
| | - Jean-Marie Bonny
- INRAE, UR QuaPA, F-63122 Saint-Gènes-Champanelle, France; INRAE, AgroResonance Facility, F-63122 Saint-Genès-Champanelle, France
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Kokuryo D, Kumamoto E, Kuroda K. Recent technological advancements in thermometry. Adv Drug Deliv Rev 2020; 163-164:19-39. [PMID: 33217482 DOI: 10.1016/j.addr.2020.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 07/25/2020] [Accepted: 11/02/2020] [Indexed: 12/12/2022]
Abstract
Thermometry is the key factor for achieving successful thermal therapy. Although invasive thermometry with a probe has been used for more than four decades, this method can only detect the local temperature within the probing volume. Noninvasive temperature imaging using a tomographic technique is ideal for monitoring hot-spot formation in the human body. Among various techniques, such as X-ray computed tomography, microwave tomography, echo sonography, and magnetic resonance (MR) imaging, the proton resonance frequency shift method of MR thermometry is the only method currently available for clinical practice because its temperature sensitivity is consistent in most aqueous tissues and can be easily observed using common clinical scanners. New techniques are being proposed to improve the robustness of this method against tissue motion. MR techniques for fat thermometry were also developed based on relaxation times. One of the latest non-MR techniques to attract attention is photoacoustic imaging.
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Affiliation(s)
- Daisuke Kokuryo
- Graduate School of System Informatics, Kobe University, Japan
| | - Etsuko Kumamoto
- Information Science and Technology Center, Kobe University, Japan
| | - Kagayaki Kuroda
- School of Information Science and Technology, Tokai University, Japan; Center for Frontier Medical Engineering, Chiba University, Japan.
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Odéen H, Parker DL. Magnetic resonance thermometry and its biological applications - Physical principles and practical considerations. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2019; 110:34-61. [PMID: 30803693 PMCID: PMC6662927 DOI: 10.1016/j.pnmrs.2019.01.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 01/23/2019] [Indexed: 05/25/2023]
Abstract
Most parameters that influence the magnetic resonance imaging (MRI) signal experience a temperature dependence. The fact that MRI can be used for non-invasive measurements of temperature and temperature change deep inside the human body has been known for over 30 years. Today, MR temperature imaging is widely used to monitor and evaluate thermal therapies such as radio frequency, microwave, laser, and focused ultrasound therapy. In this paper we cover the physical principles underlying the biological applications of MR temperature imaging and discuss practical considerations and remaining challenges. For biological tissue, the MR signal of interest comes mostly from hydrogen protons of water molecules but also from protons in, e.g., adipose tissue and various metabolites. Most of the discussed methods, such as those using the proton resonance frequency (PRF) shift, T1, T2, and diffusion only measure temperature change, but measurements of absolute temperatures are also possible using spectroscopic imaging methods (taking advantage of various metabolite signals as internal references) or various types of contrast agents. Currently, the PRF method is the most used clinically due to good sensitivity, excellent linearity with temperature, and because it is largely independent of tissue type. Because the PRF method does not work in adipose tissues, T1- and T2-based methods have recently gained interest for monitoring temperature change in areas with high fat content such as the breast and abdomen. Absolute temperature measurement methods using spectroscopic imaging and contrast agents often offer too low spatial and temporal resolution for accurate monitoring of ablative thermal procedures, but have shown great promise in monitoring the slower and usually less spatially localized temperature change observed during hyperthermia procedures. Much of the current research effort for ablative procedures is aimed at providing faster measurements, larger field-of-view coverage, simultaneous monitoring in aqueous and adipose tissues, and more motion-insensitive acquisitions for better precision measurements in organs such as the heart, liver, and kidneys. For hyperthermia applications, larger coverage, motion insensitivity, and simultaneous aqueous and adipose monitoring are also important, but great effort is also aimed at solving the problem of long-term field drift which gets interpreted as temperature change when using the PRF method.
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Affiliation(s)
- Henrik Odéen
- University of Utah, Utah Center for Advanced Imaging Research, Department of Radiology and Imaging Sciences, 729 Arapeen Drive, Salt Lake City, UT 84108-1217, USA.
| | - Dennis L Parker
- University of Utah, Utah Center for Advanced Imaging Research, Department of Radiology and Imaging Sciences, 729 Arapeen Drive, Salt Lake City, UT 84108-1217, USA.
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Kuroda K. MR techniques for guiding high-intensity focused ultrasound (HIFU) treatments. J Magn Reson Imaging 2017; 47:316-331. [PMID: 28580706 DOI: 10.1002/jmri.25770] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 05/02/2017] [Indexed: 12/17/2022] Open
Abstract
To make full use of the ability of magnetic resonance (MR) to guide high-intensity focused ultrasound (HIFU) treatment, effort has been made to improve techniques for thermometry, motion tracking, and sound beam visualization. For monitoring rapid temperature elevation with proton resonance frequency (PRF) shift, data acquisition and processing can be accelerated with parallel imaging and/or sparse sampling in conjunction with appropriate signal processing methods. Thermometry should be robust against tissue motion, motion-induced magnetic field variation, and susceptibility change. Thus, multibaseline, referenceless, or hybrid techniques have become important. In cases with adipose or bony tissues, for which PRF shift cannot be used, thermometry with relaxation times or signal intensity may be utilized. Motion tracking is crucial not only for thermometry but also for targeting the focus of an ultrasound in moving organs such as the liver, kidney, or heart. Various techniques for motion tracking, such as those based on an anatomical image atlas with optical-flow displacement detection, a navigator echo to seize the diaphragm position, and/or rapid imaging to track vessel positions, have been proposed. Techniques for avoiding the ribcage and near-field heating have also been examined. MR acoustic radiation force imaging (MR-ARFI) is an alternative to thermometry that can identify the location and shape of the focal spot and sound beam path. This technique could be useful for treating heterogeneous tissue regions or performing transcranial therapy. All of these developments, which will be discussed further in this review, expand the applicability of HIFU treatments to a variety of clinical targets while maintaining safety and precision. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;47:316-331.
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Affiliation(s)
- Kagayaki Kuroda
- Department of Human and Information Science, School of Information Science and Technology, Tokai University, Hiratsuka, Kanagawa, Japan.,Center for Frontier Medical Engineering, Chiba University, Inage, Chiba, Japan
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Lam MK, Bakker CJG, Moonen CTW, Viergever MA, Bartels LW. Short and long time MR signal behavior of randomly distributed water and fat-numerical simulations. NMR IN BIOMEDICINE 2016; 29:1634-1643. [PMID: 27687017 DOI: 10.1002/nbm.3615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 07/29/2016] [Accepted: 08/07/2016] [Indexed: 06/06/2023]
Abstract
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. Since water and fat are within the same system, the fat signal behavior may show similarities with water, with differences in short and long time scales. This could complicate fat-referenced MR thermometry (MRT) methods such as multi-gradient echo-based (MGE) MRT. Simulations were performed using a numerical phantom comprising spherical fat objects embedded in a spherical water medium. To characterize the fat signal, the theoretical signal description of water was fitted to the simulated fat signal. The simulated signals were sampled as an MGE signal and MGE MRT was used to calculate temperatures. The sampling was done with and without delay, to investigate the effect on the temperature error of the time ranges in which the signal was sampled. It was confirmed that the fat signal behavior was similar to that of water and consisted of two regimes. The separation between the short and long time scales was approximately at 55 ms for fat, as compared with 8.9 ms for water. Without delayed signal sampling, the MGE MRT temperature error was about 2.5°C. With delayed sampling such that both the water and the fat signals were either in the short or in the long time scale the error was reduced to 0.2°C.
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Affiliation(s)
- Mie K Lam
- Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, Room Q.02.445, CX, Utrecht, The Netherlands.
| | - Chris J G Bakker
- Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, Room Q.02.445, CX, Utrecht, The Netherlands
| | - Chrit T W Moonen
- Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, Room Q.02.445, CX, Utrecht, The Netherlands
| | - Max A Viergever
- Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, Room Q.02.445, CX, Utrecht, The Netherlands
| | - Lambertus W Bartels
- Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, Room Q.02.445, CX, Utrecht, The Netherlands
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Hartmann J, Gellermann J, Brandt T, Schmidt M, Pyatykh S, Hesser J, Ott O, Fietkau R, Bert C. Optimization of Single Voxel MR Spectroscopy Sequence Parameters and Data Analysis Methods for Thermometry in Deep Hyperthermia Treatments. Technol Cancer Res Treat 2016; 16:470-481. [PMID: 27422012 DOI: 10.1177/1533034616656310] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE The difference in the resonance frequency of water and methylene moieties of lipids quantifies in magnetic resonance spectroscopy the absolute temperature using a predefined calibration curve. The purpose of this study was the investigation of peak evaluation methods and the magnetic resonance spectroscopy sequence (point-resolved spectroscopy) parameter optimization that enables thermometry during deep hyperthermia treatments. MATERIALS AND METHODS Different Lorentz peak-fitting methods and a peak finding method using singular value decomposition of a Hankel matrix were compared. Phantom measurements on organic substances (mayonnaise and pork) were performed inside the hyperthermia 1.5-T magnetic resonance imaging system for the parameter optimization study. Parameter settings such as voxel size, echo time, and flip angle were varied and investigated. RESULTS Usually all peak analyzing methods were applicable. Lorentz peak-fitting method in MATLAB proved to be the most stable regardless of the number of fitted peaks, yet the slowest method. The examinations yielded an optimal parameter combination of 8 cm3 voxel volume, 55 millisecond echo time, and a 90° excitation pulse flip angle. CONCLUSION The Lorentz peak-fitting method in MATLAB was the most reliable peak analyzing method. Measurements in homogeneous and heterogeneous phantoms resulted in optimized parameters for the magnetic resonance spectroscopy sequence for thermometry.
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Affiliation(s)
- J Hartmann
- 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - J Gellermann
- 2 Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany.,3 Praxis/Zentrum für Strahlentherapie und Radioonkologie, Berlin, Germany
| | - T Brandt
- 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - M Schmidt
- 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - S Pyatykh
- 4 Medical Faculty Mannheim, Experimental Radiation Oncology, Heidelberg University, Mannheim, Germany
| | - J Hesser
- 4 Medical Faculty Mannheim, Experimental Radiation Oncology, Heidelberg University, Mannheim, Germany
| | - O Ott
- 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - R Fietkau
- 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - C Bert
- 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Lee N, Yoo D, Ling D, Cho MH, Hyeon T, Cheon J. Iron Oxide Based Nanoparticles for Multimodal Imaging and Magnetoresponsive Therapy. Chem Rev 2015; 115:10637-89. [PMID: 26250431 DOI: 10.1021/acs.chemrev.5b00112] [Citation(s) in RCA: 584] [Impact Index Per Article: 64.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Nohyun Lee
- School of Advanced Materials Engineering, Kookmin University , Seoul 136-702, Korea
| | - Dongwon Yoo
- Department of Chemistry, Yonsei University , Seoul 120-749, Korea
| | - Daishun Ling
- Center for Nanoparticle Research, Institute for Basic Science (IBS) , Seoul 151-742, Korea.,School of Chemical and Biological Engineering, Seoul National University , Seoul 151-742, Korea.,Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University , Hangzhou 310058, PR China
| | - Mi Hyeon Cho
- Department of Chemistry, Yonsei University , Seoul 120-749, Korea
| | - Taeghwan Hyeon
- Center for Nanoparticle Research, Institute for Basic Science (IBS) , Seoul 151-742, Korea.,School of Chemical and Biological Engineering, Seoul National University , Seoul 151-742, Korea
| | - Jinwoo Cheon
- Department of Chemistry, Yonsei University , Seoul 120-749, Korea
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Baron P, Deckers R, Bouwman JG, Bakker CJG, de Greef M, Viergever MA, Moonen CTW, Bartels LW. Influence of water and fat heterogeneity on fat-referenced MR thermometry. Magn Reson Med 2015; 75:1187-97. [PMID: 25940426 DOI: 10.1002/mrm.25727] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 12/25/2022]
Abstract
PURPOSE To investigate the effect of the aqueous and fatty tissue magnetic susceptibility distribution on absolute and relative temperature measurements as obtained directly from the water/fat (w/f) frequency difference. METHODS Absolute thermometry was investigated using spherical phantoms filled with pork and margarine, which were scanned in three orthogonal orientations. To evaluate relative fat referencing, multigradient echo scans were acquired before and after heating pork tissue via high-intensity focused ultrasound (HIFU). Simulations were performed to estimate the errors that can be expected in human breast tissue. RESULTS The sphere experiment showed susceptibility-related errors of 8.4 °C and 0.2 °C for pork and margarine, respectively. For relative fat referencing measurements, fat showed pronounced phase changes of opposite polarity to aqueous tissue. The apparent mean temperature for a numerical breast model assumed to be 37 °C was 47.2 ± 21.6 °C. Simulations of relative fat referencing for a HIFU sonication (ΔT = 29.7 °C) yielded a maximum temperature error of 6.6 °C compared with 2.5 °C without fat referencing. CONCLUSION Variations in the observed frequency difference between water and fat are largely due to variations in the w/f spatial distribution. This effect may lead to considerable errors in absolute MR thermometry. Additionally, fat referencing may exacerbate rather than correct for proton resonance frequency shift-temperature measurement errors.
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Affiliation(s)
- Paul Baron
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
| | - Roel Deckers
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
| | - Job G Bouwman
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
| | - Chris J G Bakker
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
| | - Martijn de Greef
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
| | - Max A Viergever
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
| | - Chrit T W Moonen
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
| | - Lambertus W Bartels
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
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Deckers R, Sprinkhuizen SM, Crielaard BJ, Ippel JH, Boelens R, Bakker CJG, Storm G, Lammers T, Bartels LW. Absolute MR thermometry using nanocarriers. CONTRAST MEDIA & MOLECULAR IMAGING 2014; 9:283-90. [PMID: 24706612 DOI: 10.1002/cmmi.1572] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 08/16/2013] [Accepted: 09/04/2013] [Indexed: 11/06/2022]
Abstract
Accurate time-resolved temperature mapping is crucial for the safe use of hyperthermia-mediated drug delivery. We here propose a magnetic resonance imaging temperature mapping method in which drug delivery systems serve not only to improve tumor targeting, but also as an accurate and absolute nano-thermometer. This method is based on the temperature-dependent chemical shift difference between water protons and the protons in different groups of drug delivery systems. We show that the chemical shift of the protons in the ethylene oxide group in polyethylene glycol (PEG) is temperature-independent, whereas the proton resonance of water decreases with increasing temperature. The frequency difference between both resonances is linear and does not depend on pH and physiological salt conditions. In addition, we show that the proton resonance of the methyl group in N-(2-hydroxypropyl)-methacrylamide (HPMA) is temperature-independent. Therefore, PEGylated liposomes, polymeric mPEG-b-pHPMAm-Lac2 micelles and HPMA copolymers can provide a temperature-independent reference frequency for absolute magnetic resonance (MR) thermometry. Subsequently, we show that multigradient echo MR imaging with PEGylated liposomes in situ allows accurate, time-resolved temperature mapping. In conclusion, nanocarrier materials may serve as highly versatile tools for tumor-targeted drug delivery, acting not only as hyperthermia-responsive drug delivery systems, but also as accurate and precise nano-thermometers.
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Affiliation(s)
- Roel Deckers
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands
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Lin JS, Hwang KP, Jackson EF, Hazle JD, Stafford RJ, Taylor BA. Multiparametric fat-water separation method for fast chemical-shift imaging guidance of thermal therapies. Med Phys 2013; 40:103302. [PMID: 24089932 DOI: 10.1118/1.4819815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
PURPOSE A k-means-based classification algorithm is investigated to assess suitability for rapidly separating and classifying fat/water spectral peaks from a fast chemical shift imaging technique for magnetic resonance temperature imaging. Algorithm testing is performed in simulated mathematical phantoms and agar gel phantoms containing mixed fat/water regions. METHODS Proton resonance frequencies (PRFs), apparent spin-spin relaxation (T2*) times, and T1-weighted (T1-W) amplitude values were calculated for each voxel using a single-peak autoregressive moving average (ARMA) signal model. These parameters were then used as criteria for k-means sorting, with the results used to determine PRF ranges of each chemical species cluster for further classification. To detect the presence of secondary chemical species, spectral parameters were recalculated when needed using a two-peak ARMA signal model during the subsequent classification steps. Mathematical phantom simulations involved the modulation of signal-to-noise ratios (SNR), maximum PRF shift (MPS) values, analysis window sizes, and frequency expansion factor sizes in order to characterize the algorithm performance across a variety of conditions. In agar, images were collected on a 1.5T clinical MR scanner using acquisition parameters close to simulation, and algorithm performance was assessed by comparing classification results to manually segmented maps of the fat/water regions. RESULTS Performance was characterized quantitatively using the Dice Similarity Coefficient (DSC), sensitivity, and specificity. The simulated mathematical phantom experiments demonstrated good fat/water separation depending on conditions, specifically high SNR, moderate MPS value, small analysis window size, and low but nonzero frequency expansion factor size. Physical phantom results demonstrated good identification for both water (0.997 ± 0.001, 0.999 ± 0.001, and 0.986 ± 0.001 for DSC, sensitivity, and specificity, respectively) and fat (0.763 ± 0.006, 0.980 ± 0.004, and 0.941 ± 0.002 for DSC, sensitivity, and specificity, respectively). Temperature uncertainties, based on PRF uncertainties from a 5 × 5-voxel ROI, were 0.342 and 0.351°C for pure and mixed fat/water regions, respectively. Algorithm speed was tested using 25 × 25-voxel and whole image ROIs containing both fat and water, resulting in average processing times per acquisition of 2.00 ± 0.07 s and 146 ± 1 s, respectively, using uncompiled MATLAB scripts running on a shared CPU server with eight Intel Xeon(TM) E5640 quad-core processors (2.66 GHz, 12 MB cache) and 12 GB RAM. CONCLUSIONS Results from both the mathematical and physical phantom suggest the k-means-based classification algorithm could be useful for rapid, dynamic imaging in an ROI for thermal interventions. Successful separation of fat/water information would aid in reducing errors from the nontemperature sensitive fat PRF, as well as potentially facilitate using fat as an internal reference for PRF shift thermometry when appropriate. Additionally, the T1-W or R2* signals may be used for monitoring temperature in surrounding adipose tissue.
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Affiliation(s)
- Jonathan S Lin
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, Texas 77005 and Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030
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11
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Kuroda K, Iwabuchi T, Obara M, Honda M, Saito K, Imai Y. Temperature dependence of relaxation times in proton components of fatty acids. Magn Reson Med Sci 2012; 10:177-83. [PMID: 21960000 DOI: 10.2463/mrms.10.177] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We examined the temperature dependence of relaxation times in proton components of fatty acids in various samples in vitro at 11 tesla as a standard calibration data for quantitative temperature imaging of fat. The spin-lattice relaxation time, T(1), of both the methylene (CH(2)) chain and terminal methyl (CH(3)) was linearly related to temperature (r>0.98, P<0.001) in samples of animal fat. The temperature coefficients for the 2 primary proton components differed significantly; in 5 bovine fat samples, the coefficient at 30 °C was 1.79±0.07 (%/°C) for methylene and 2.98±0.38 (%/°C) for methyl. Numerical simulations based on such a difference demonstrated the possibility of considerable error from inconsistent ratios in fatty acid components when calibrating and estimating temperature. The error reached 3.3 °C per 15 °C in temperature elevation when we used a pure CH(2) signal for calibration and observed the signal with 18% of CH(3) to estimate temperature. These findings suggested that separating the fatty acid components would significantly improve accuracy in quantitative thermometry for fat. Use of the T(1) of CH(2) seems promising in terms of reliability and reproducibility in measuring temperature of fat.
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Affiliation(s)
- Kagayaki Kuroda
- Graduate School of Engineering, Tokai University, Kanagawa, Japan.
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12
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Taylor BA, Elliott AM, Hwang KP, Hazle JD, Stafford RJ. Correlation between the temperature dependence of intrinsic MR parameters and thermal dose measured by a rapid chemical shift imaging technique. NMR IN BIOMEDICINE 2011; 24:1414-1421. [PMID: 21721063 PMCID: PMC3190595 DOI: 10.1002/nbm.1707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 12/23/2010] [Accepted: 02/15/2011] [Indexed: 05/31/2023]
Abstract
In order to investigate simultaneous MR temperature imaging and direct validation of tissue damage during thermal therapy, temperature-dependent signal changes in proton resonance frequency (PRF) shifts, R(2)* values, and T1-weighted amplitudes are measured from one technique in ex vivo tissue. Using a multigradient echo acquisition and the Stieglitz-McBride algorithm, the temperature sensitivity coefficients of these parameters are measured in each tissue at high spatiotemporal resolutions (1.6 x 1.6 x 4 mm 3,≤ 5sec) at the range of 25-61 °C. Non-linear changes in MR parameters are examined and correlated with an Arrhenius rate dose model of thermal damage. Using logistic regression, the probability of changes in these parameters is calculated as a function of thermal dose to determine if changes correspond to thermal damage. Temperature sensitivity of R(2)* and, in some cases, T1-weighted amplitudes are statistically different before and after thermal damage occurred. Significant changes in the slopes of R(2)* as a function of temperature are observed. Logistic regression analysis shows that these changes could be accurately predicted using the Arrhenius rate dose model (Ω = 1.01 ± 0.03), thereby showing that the changes in R(2)* could be direct markers of protein denaturation. Overall, by using a chemical shift imaging technique with simultaneous temperature estimation, R(2)* mapping and T1-W imaging, it is shown that changes in the sensitivity of R(2)* and, to a lesser degree, T1-W amplitudes are measured in ex vivo tissue when thermal damage is expected to occur. These changes could possibly be used for direct validation of thermal damage in contrast to model-based predictions.
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Affiliation(s)
- Brian A. Taylor
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
- The University of Texas Graduate School of Biomedical Sciences, Houston, Texas
| | - Andrew M. Elliott
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
| | - Ken-Pin Hwang
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
- Applied Science Laboratory, GE Healthcare, Waukesha, Wisconsin
| | - John D. Hazle
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
| | - R. Jason Stafford
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
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Taylor BA, Elliott AM, Hwang KP, Shetty A, Hazle JD, Stafford RJ. Measurement of temperature dependent changes in bone marrow using a rapid chemical shift imaging technique. J Magn Reson Imaging 2011; 33:1128-35. [PMID: 21509871 DOI: 10.1002/jmri.22537] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
PURPOSE To provide quantitative temperature monitoring for thermal therapies in bone marrow by measuring temperature-dependent signal changes in the bone marrow of ex vivo canine femurs heated with a 980-nm laser at 1.5T and 3.0T. MATERIALS AND METHODS Using a multi-gradient echo (≤ 16) acquisition and signal modeling with the Stieglitz-McBride algorithm, the temperature sensitivity coefficients (TSC, ppm/°C) of water and multiple lipid components' proton resonance frequency (PRF) values are measured at high spatiotemporal resolutions (1.6 × 1.6 × 4 mm(3) , ≤ 5 seconds). Responses in R(2) * and amplitudes of each peak were also measured as a function of temperature simultaneously. RESULTS Calibrations demonstrate that lipid signal may be used to compensate for B(0) errors to provide accurate temperature readings (<1.0°C). Over a temperature range of 17.2-57.2°C, the TSCs after correction to a bulk methylene reference are -0.87 × 10(-2) ± 4.7 × 10(-4) ppm/°C and -0.87 × 10(-2) ± 4.0 × 10(-4) ppm/°C for 1.5T and 3.0T, respectively. CONCLUSION Overall, we demonstrate that accurate and precise temperature measurements can be made in bone marrow. In addition, the relationship of R(2) * and signal amplitudes with respect to temperature are shown to differ significantly where conformal changes are predicted by Arrhenius rate model analysis.
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Affiliation(s)
- Brian A Taylor
- Department of Imaging Physics, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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14
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Mei CS, Mulkern RV, Oshio K, Chen NK, Madore B, Panych LP, Hynynen K, McDannold NJ. Ultrafast 1D MR thermometry using phase or frequency mapping. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2011; 25:5-14. [PMID: 21800192 DOI: 10.1007/s10334-011-0272-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 06/28/2011] [Accepted: 06/30/2011] [Indexed: 11/29/2022]
Abstract
OBJECT To develop an ultrafast MRI-based temperature monitoring method for application during rapid ultrasound exposures in moving organs. MATERIALS AND METHODS A slice selective 90° - 180° pair of RF pulses was used to solicit an echo from a column, which was then sampled with a train of gradient echoes. In a gel phantom, phase changes of each echo were compared to standard gradient-echo thermometry, and temperature monitoring was tested during focused ultrasound sonications. Signal-to-noise ratio (SNR) performance was evaluated in vivo in a rabbit brain, and feasibility was tested in a human heart. RESULTS The correlation between each echo in the acquisition and MRI-based temperature measurements was good (R = 0.98 ± 0.03). A temperature sampling rate of 19 Hz was achieved at 3T in the gel phantom. It was possible to acquire the water frequency in the beating heart muscle with 5-Hz sampling rate during a breath hold. CONCLUSION Ultrafast thermometry via phase or frequency monitoring along single columns was demonstrated. With a temporal resolution around 50 ms, it may be possible to monitor focal heating produced by short ultrasound pulses.
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Affiliation(s)
- Chang-Sheng Mei
- Department of Physics, Boston College, Chestnut Hill, MA, USA.
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15
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Sprinkhuizen SM, Bakker CJG, Bartels LW. Absolute MR thermometry using time-domain analysis of multi-gradient-echo magnitude images. Magn Reson Med 2010; 64:239-48. [DOI: 10.1002/mrm.22429] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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16
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Pan X, Li C, Ying K, Weng D, Qin W, Li K. Model-based PRFS thermometry using fat as the internal reference and the extended Prony algorithm for model fitting. Magn Reson Imaging 2010; 28:418-26. [DOI: 10.1016/j.mri.2009.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 08/05/2009] [Accepted: 11/25/2009] [Indexed: 10/19/2022]
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17
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Li C, Pan X, Ying K, Zhang Q, An J, Weng D, Qin W, Li K. An internal reference model-based PRF temperature mapping method with Cramer-Rao lower bound noise performance analysis. Magn Reson Med 2010; 62:1251-60. [PMID: 19780176 DOI: 10.1002/mrm.22121] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The conventional phase difference method for MR thermometry suffers from disturbances caused by the presence of lipid protons, motion-induced error, and field drift. A signal model is presented with multi-echo gradient echo (GRE) sequence using a fat signal as an internal reference to overcome these problems. The internal reference signal model is fit to the water and fat signals by the extended Prony algorithm and the Levenberg-Marquardt algorithm to estimate the chemical shifts between water and fat which contain temperature information. A noise analysis of the signal model was conducted using the Cramer-Rao lower bound to evaluate the noise performance of various algorithms, the effects of imaging parameters, and the influence of the water:fat signal ratio in a sample on the temperature estimate. Comparison of the calculated temperature map and thermocouple temperature measurements shows that the maximum temperature estimation error is 0.614 degrees C, with a standard deviation of 0.06 degrees C, confirming the feasibility of this model-based temperature mapping method. The influence of sample water:fat signal ratio on the accuracy of the temperature estimate is evaluated in a water-fat mixed phantom experiment with an optimal ratio of approximately 0.66:1.
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Affiliation(s)
- Cheng Li
- Engineering Physics, Tsinghua University, Beijing, People's Republic of China
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18
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Abstract
Among various proton magnetic resonance (MR) parameters, such as longitudinal relaxation time, transverse relaxation time, diffusion coefficient and chemical shift, the chemical shift of water protons is recognized as the most reliable indicator of temperature. The chemical shift is the only frequency-based parameter and is independent of the other parameters, which are measured based on the intensity of the MR signal. In this paper, the basic principle and the recent progress in imaging temperature by spectroscopic techniques using the water proton chemical shift are discussed. The advantages of spectroscopic imaging over phase mapping for measuring temperature are that the former can distinguish water resonance from other resonances, and that another resonance can be used as an internal reference to reduce the effects of external magnetic field instability, tissue susceptibility and inter-scan tissue movement or deformation. Methods utilizing various magnetic resonance spectroscopy (MRS) techniques, such as single voxel spectroscopy, conventional magnetic resonance spectroscopic imaging (MRSI), echo planar spectroscopic imaging (EPSI) and line scan echo planar spectroscopic imaging (LSEPSI) are discussed.
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Affiliation(s)
- Kagayaki Kuroda
- Molecular Imaging Research Group, Institute of Biomedical Research and Innovation, Kobe, Japan.
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McDannold N. Quantitative MRI-based temperature mapping based on the proton resonant frequency shift: Review of validation studies. Int J Hyperthermia 2009; 21:533-46. [PMID: 16147438 DOI: 10.1080/02656730500096073] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
MRI-based temperature imaging that exploits the temperature-sensitive water proton resonant frequency shift is currently the only available method for reliable quantification of temperature changes in vivo. Extensive pre-clinical work has been performed to validate this method for guiding thermal therapies. That work has shown the method to be useful for all stages of the thermal therapy, from resolving heating below the threshold for damage to ensuring that the thermal exposure is sufficient within the target volume and protecting surrounding critical structures and to accurately predicting the extent of the ablated volume. In this paper, these validation studies will be reviewed. In addition, clinical studies that have shown this method feasible in human treatments will be overviewed.
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Affiliation(s)
- N McDannold
- Department of Radiology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA.
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Taylor BA, Hwang KP, Hazle JD, Stafford RJ. Autoregressive moving average modeling for spectral parameter estimation from a multigradient echo chemical shift acquisition. Med Phys 2009; 36:753-64. [PMID: 19378736 DOI: 10.1118/1.3075819] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The authors investigated the performance of the iterative Steiglitz-McBride (SM) algorithm on an autoregressive moving average (ARMA) model of signals from a fast, sparsely sampled, multiecho, chemical shift imaging (CSI) acquisition using simulation, phantom, ex vivo, and in vivo experiments with a focus on its potential usage in magnetic resonance (MR)-guided interventions. The ARMA signal model facilitated a rapid calculation of the chemical shift, apparent spin-spin relaxation time (T2*), and complex amplitudes of a multipeak system from a limited number of echoes (< or equal 16). Numerical simulations of one- and two-peak systems were used to assess the accuracy and uncertainty in the calculated spectral parameters as a function of acquisition and tissue parameters. The measured uncertainties from simulation were compared to the theoretical Cramer-Rao lower bound (CRLB) for the acquisition. Measurements made in phantoms were used to validate the T2* estimates and to validate uncertainty estimates made from the CRLB. We demonstrated application to real-time MR-guided interventions ex vivo by using the technique to monitor a percutaneous ethanol injection into a bovine liver and in vivo to monitor a laser-induced thermal therapy treatment in a canine brain. Simulation results showed that the chemical shift and amplitude uncertainties reached their respective CRLB at a signal-to-noise ratio (SNR) > or =5 for echo train lengths (ETLs) > or =4 using a fixed echo spacing of 3.3 ms. T2* estimates from the signal model possessed higher uncertainties but reached the CRLB at larger SNRs and/or ETLs. Highly accurate estimates for the chemical shift (<0.01 ppm) and amplitude (<1.0%) were obtained with > or =4 echoes and for T2*(<1.0%) with > or =7 echoes. We conclude that, over a reasonable range of SNR, the SM algorithm is a robust estimator of spectral parameters from fast CSI acquisitions that acquire < or =16 echoes for one- and two-peak systems. Preliminary ex vivo and in vivo experiments corroborated the results from simulation experiments and further indicate the potential of this technique for MR-guided interventional procedures with high spatiotemporal resolution approximately 1.6 x 1.6 x 4 mm3 in < or =5 s.
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Affiliation(s)
- Brian A Taylor
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
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Taylor BA, Hwang KP, Elliott AM, Shetty A, Hazle JD, Stafford RJ. Dynamic chemical shift imaging for image-guided thermal therapy: analysis of feasibility and potential. Med Phys 2008; 35:793-803. [PMID: 18383702 DOI: 10.1118/1.2831915] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A fast chemical shift imaging (CSI) technique based on a multiple gradient-recalled acquisition using a small number of echoes with intentional aliasing of the reference lipid peak is studied to determine its feasibility for temperature monitoring. Simulations were implemented to find parameters where the lipid and water peaks can be measured using a Fourier-based peak fitting approach as well as using an innovative autoregressive moving average technique. A phantom consisting of 50% mayonnaise/50% lemon juice was calibrated to temperature and compared to literature values. A porcine kidney was treated ex vivo with an external laser and imaged with the CSI technique with comparisons to temperature readings from a fluoroptic monitoring system and complex phase difference (CPD) calculations. To demonstrate the technique in vivo, a Balb/c mouse with a CT26 xenograft in the subcutaneous lower back was treated using gold-coated, silica-core nanoshells heated with an 808 nm interstitial laser. Compared to standard CPD techniques using a two-dimensional fast spoiled gradient recalled echo, this technique maintains spatiotemporal resolution, has high signal-to-noise ratio and accuracy over a wide range of T2* tissue values, can separate water and lipid signals, and additionally can use the lipid peak, when present, as an internal reference.
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Affiliation(s)
- Brian A Taylor
- Department of Imaging Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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22
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McDannold N, Barnes AS, Rybicki FJ, Oshio K, Chen NK, Hynynen K, Mulkern RV. Temperature mapping considerations in the breast with line scan echo planar spectroscopic imaging. Magn Reson Med 2008; 58:1117-23. [PMID: 18046702 DOI: 10.1002/mrm.21322] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A line-scan echo planar spectroscopic imaging (LSEPSI) sequence was used to serially acquire spectra from 4,096 voxels every 6.4 s throughout the breasts of nine female subjects in vivo. Data from the serial acquisitions were analyzed to determine the potential of the technique to characterize temperature changes using either the water frequency alone or the water-methylene frequency difference. Fluctuations of the apparent temperature change under these conditions of no heating were smallest using the water-methylene frequency difference, most probably due to a substantial reduction of motion effects both within and without the imaged plane. The approach offers considerable advantages over other methods for temperature change monitoring in the breast with magnetic resonance but suffers from some limitations, including the unavailability of lipid and water resonances in some voxels as well as a surprisingly large distribution of water-methylene frequency differences, which may preclude absolute temperature measurement.
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Affiliation(s)
- Nathan McDannold
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
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Shmatukha AV, Harvey PR, Bakker CJG. Correction of proton resonance frequency shift temperature maps for magnetic field disturbances using fat signal. J Magn Reson Imaging 2007; 25:579-87. [PMID: 17335067 DOI: 10.1002/jmri.20835] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To improve the immunity of the proton resonance frequency shift (PRFS) method of MRI temperature mapping against magnetic field disturbances. Since PRFS is a phase-sensitive method, it misinterprets magnetic field disturbances as artifact temperature changes. If not corrected, the resulting temperature artifacts can completely obscure the true temperature estimation, especially if the temperature elevations are small. MATERIALS AND METHODS Since the fat protons experience the same magnetic field disturbances as the water protons, but no temperature-related frequency shift, the fat signal has been used for correcting PRFS temperature maps for the disturbances. A simple correction method is proposed that has either better compensation capability than the phase correction methods previously reported or higher spatial and temporal resolution than the spectroscopic correction methods previously reported. The evaluated method is based on the utilization of several gradient and spin echoes acquired within one repetition interval with water- and fat-selective scans. RESULTS In a series of phantom experiments, the improved method is shown to enable the reconstruction of accurate temperature maps in spite of interscan motion, suboptimal fat-water separation, and a wide range of magnetic field disturbances. CONCLUSION Our approach can be used for the guidance of thermal therapies involving tissues containing fat or surrounded by fat.
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Affiliation(s)
- Andriy V Shmatukha
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands.
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24
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Stafford RJ, Hazle JD. Magnetic resonance temperature imaging for focused ultrasound surgery: a review. Top Magn Reson Imaging 2006; 17:153-63. [PMID: 17414072 DOI: 10.1097/rmr.0b013e3180377bc3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Magnetic resonance temperature imaging (MRTI) is an enabling technology that has recently demonstrated the potential to bring the emerging minimally invasive image-guided thermal therapy procedures, such as radiofrequency, microwave, laser, ultrasound, and cryosurgery, into the clinical setting with a level of safety and efficacy not previously possible. By coupling the wealth of soft tissue contrast mechanisms available with magnetic resonance imaging with its intrinsic temperature sensitivity, magnetic resonance imaging is in a unique position to provide image-guided treatment planning and verification and quantitative or qualitative feedback during treatment delivery, heightening of the control the physician has over the method, and enhancement of the ability to deliver conformal treatments. The basic principles behind MRTI technology and its application to minimally invasive thermal therapy during ultrasound thermal therapy delivery are reviewed in this study.
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Affiliation(s)
- R Jason Stafford
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
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25
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Mulkern RV, Chen NK, Oshio K, Panych LP, Rybicki FJ, Gambarota G. Fast spectroscopic imaging strategies for potential applications in fMRI. Magn Reson Imaging 2005; 22:1395-405. [PMID: 15707789 DOI: 10.1016/j.mri.2004.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Accepted: 10/08/2004] [Indexed: 01/28/2023]
Abstract
Technical aspects of two general fast spectroscopic imaging (SI) strategies, one based on gradient echo trains and the other on spin echo trains, are reviewed within the context of potential applications in the field of functional magnetic resonance imaging (fMRI). Fast spectroscopic imaging of water may prove useful for identifying mechanisms underlying the blood oxygenation level dependence (BOLD) of the water signal during brain activation studies. Reasonably rapid mapping of changes in proton signals from brain metabolites, like lactate, creatine or even neurotransmitter associated metabolites like GABA, is substantially more challenging but technically feasible particularly as higher field strengths become available. Fast spectroscopic methods directed towards the 31P signals from phosphocreatine (PCr) and adenosine tri-phosphates (ATP) are also technically feasible and may prove useful for studying cerebral energetics within fMRI contexts.
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Affiliation(s)
- Robert V Mulkern
- Department of Radiology, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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26
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Chen NK, Oshio K, Panych LP, Rybicki FJ, Mulkern RV. Spatially selective T2 and T2 * measurement with line-scan echo-planar spectroscopic imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2004; 171:90-96. [PMID: 15504686 DOI: 10.1016/j.jmr.2004.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Revised: 07/28/2004] [Indexed: 05/24/2023]
Abstract
Line-scan echo planar spectroscopic imaging (LSEPSI) is applied to quickly measure the T2 and T2* relaxation time constants in pre-selected 2D or 3D regions. Results from brain imaging studies at 3T suggest that the proposed method may prove valuable for both basic research (e.g., quantifying the changes of T2/T2* values in functional MRI with blood oxygenation level-dependent contrast) and clinical studies (e.g., measuring the T2' shortening due to iron deposition). The proposed spatially selective T2 and T2* mapping technique is especially well suited for studies, where T2/T2* quantification needs to be performed dynamically in a pre-selected 2D or 3D region.
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Affiliation(s)
- Nan-kuei Chen
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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27
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Kuroda K, Takei N, Mulkern RV, Oshio K, Nakai T, Okada T, Matsumura A, Yanaka K, Hynynen K, Jolesz FA. Feasibility of Internally Referenced Brain Temperature Imaging with a Metabolite Signal. Magn Reson Med Sci 2003; 2:17-22. [PMID: 16210815 DOI: 10.2463/mrms.2.17] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The feasibility of using a metabolite signal as an internal reference for self-referenced temperature distribution measurement was examined. Line scan echo-planar spectroscopic imaging (LSEPSI) was applied to obtain quick multi-voxel spectroscopic measurements and to avoid possible spectral degradation from motion. Temperature distribution in a rabbit brain in vivo was successfully visualized by means of the chemical shift of water, which was measured by using naturally abundant (up to 10 mM) N-acetyl-aspartate (NAA) as the reference signal. Unlike the phase-mapping approach, this technique does not require a pixel-by-pixel subtraction. Therefore, in theory, it is more resistant to inter-scan motion or changes in susceptibility. The spatial and temporal resolutions of this technique are 1.5 cm3 and 4.5 min. A higher signal-to-noise ratio and optimization of the water and outer-volume suppression capabilities will be required to further enhance the temperature-mapping capabilities.
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Affiliation(s)
- Kagayaki Kuroda
- Department of Image-Based Medicine, Institute of Biomedical Research and Innovation, Kobe, Japan.
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