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Kim K, Narsinh K, Ozhinsky E. Technical advances in motion-robust MR thermometry. Magn Reson Med 2024; 92:15-27. [PMID: 38501903 PMCID: PMC11132643 DOI: 10.1002/mrm.30057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 01/25/2024] [Accepted: 01/27/2024] [Indexed: 03/20/2024]
Abstract
Proton resonance frequency shift (PRFS) MR thermometry is the most common method used in clinical thermal treatments because of its fast acquisition and high sensitivity to temperature. However, motion is the biggest obstacle in PRFS MR thermometry for monitoring thermal treatment in moving organs. This challenge arises because of the introduction of phase errors into the PRFS calculation through multiple methods, such as image misregistration, susceptibility changes in the magnetic field, and intraframe motion during MRI acquisition. Various approaches for motion correction have been developed for real-time, motion-robust, and volumetric MR thermometry. However, current technologies have inherent trade-offs among volume coverage, processing time, and temperature accuracy. These tradeoffs should be considered and chosen according to the thermal treatment application. In hyperthermia treatment, precise temperature measurements are of increased importance rather than the requirement for exceedingly high temporal resolution. In contrast, ablation procedures require robust temporal resolution to accurately capture a rapid temperature rise. This paper presents a comprehensive review of current cutting-edge MRI techniques for motion-robust MR thermometry, and recommends which techniques are better suited for each thermal treatment. We expect that this study will help discern the selection of motion-robust MR thermometry strategies and inspire the development of motion-robust volumetric MR thermometry for practical use in clinics.
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Affiliation(s)
- Kisoo Kim
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, California, USA
| | - Kazim Narsinh
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, California, USA
| | - Eugene Ozhinsky
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, California, USA
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Natera-Villalba E, Ruiz-Yanzi MA, Gasca-Salas C, Matarazzo M, Martínez-Fernández R. MR-guided focused ultrasound in movement disorders and beyond: Lessons learned and new frontiers. Parkinsonism Relat Disord 2024; 122:106040. [PMID: 38378311 DOI: 10.1016/j.parkreldis.2024.106040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 02/09/2024] [Indexed: 02/22/2024]
Abstract
The development of MR-guided focused ultrasound (MRgFUS) has provided a new therapeutic tool for neuropsychiatric disorders. In contrast to previously available neurosurgical techniques, MRgFUS allows precise impact on deep brain structures without the need for incision and yields an immediate effect. In its high-intensity modality (MRgHIFU), it produces accurate therapeutic thermoablation in previously selected brain targets. Importantly, the production of the lesion is progressive and highly controlled in real-time by both neuroimaging and clinical means. MRgHIFU ablation is already an accepted and widely used treatment for medically-refractory Parkinson's disease and essential tremor. Notably, other neurological disorders and diverse brain targets, including bilateral treatments, are currently under examination. Conversely, the low-intensity modality (MRgLIFU) shows promising prospects in neuromodulation and transient blood-brain barrier opening (BBBO). In the former circumstance, MRgLIFU could serve as a powerful clinical and research tool for non-invasively modulating brain activity and function. BBBO, on the other hand, emerges as a potentially impactful method to influence disease pathogenesis and progression by increasing brain target engagement of putative therapeutic agents. While promising, these applications remain experimental. As a recently developed technology, MRgFUS is not without challenges and questions to be addressed. Further developments and broader experience are necessary to enhance MRgFUS capabilities in both research and clinical practice, as well as to define device constraints. This clinical mini-review aims to provide an overview of the main evidence of MRgFUS application and to highlight unmet needs and future potentialities of the technique.
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Affiliation(s)
- Elena Natera-Villalba
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta Del Sur, HM Hospitales, Madrid, Spain; PhD Medicine Program, Universidad Autónoma de Madrid, Madrid, Spain
| | - María-Agustina Ruiz-Yanzi
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta Del Sur, HM Hospitales, Madrid, Spain
| | - Carmen Gasca-Salas
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta Del Sur, HM Hospitales, Madrid, Spain; CIBERNED, Instituto Carlos III, Madrid, Spain; University CEU-San Pablo, Madrid, Spain
| | - Michele Matarazzo
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta Del Sur, HM Hospitales, Madrid, Spain; CIBERNED, Instituto Carlos III, Madrid, Spain
| | - Raúl Martínez-Fernández
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta Del Sur, HM Hospitales, Madrid, Spain; CIBERNED, Instituto Carlos III, Madrid, Spain; University CEU-San Pablo, Madrid, Spain.
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Mattay RR, Kim K, Shah L, Shah B, Sugrue L, Safoora F, Ozhinsky E, Narsinh KH. MR Thermometry during Transcranial MR Imaging-Guided Focused Ultrasound Procedures: A Review. AJNR Am J Neuroradiol 2023; 45:1-8. [PMID: 38123912 PMCID: PMC10756580 DOI: 10.3174/ajnr.a8038] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 08/04/2023] [Indexed: 12/23/2023]
Abstract
Interest in transcranial MR imaging-guided focused ultrasound procedures has recently grown. These incisionless procedures enable precise focal ablation of brain tissue using real-time monitoring by MR thermometry. This article will provide an updated review on clinically applicable technical underpinnings and considerations of proton resonance frequency MR thermometry, the most common clinically used MR thermometry sequence.
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Affiliation(s)
- Raghav R Mattay
- From the Department of Radiology and Biomedical Imaging (R.R.M., K.K., L. Sugrue, F.S., E.O., K.H.N.), University of California San Francisco, California
| | - Kisoo Kim
- From the Department of Radiology and Biomedical Imaging (R.R.M., K.K., L. Sugrue, F.S., E.O., K.H.N.), University of California San Francisco, California
| | - Lubdha Shah
- Department of Radiology and Neurosurgery (L. Shah), University of Utah, Salt Lake City, Utah
| | - Bhavya Shah
- Department of Radiology (B.S.), University of Texas Southwestern, Dallas, Texas
| | - Leo Sugrue
- From the Department of Radiology and Biomedical Imaging (R.R.M., K.K., L. Sugrue, F.S., E.O., K.H.N.), University of California San Francisco, California
- Department of Psychiatry (L. Sugrue), University of California San Francisco, California
| | - Fatima Safoora
- From the Department of Radiology and Biomedical Imaging (R.R.M., K.K., L. Sugrue, F.S., E.O., K.H.N.), University of California San Francisco, California
| | - Eugene Ozhinsky
- From the Department of Radiology and Biomedical Imaging (R.R.M., K.K., L. Sugrue, F.S., E.O., K.H.N.), University of California San Francisco, California
| | - Kazim H Narsinh
- From the Department of Radiology and Biomedical Imaging (R.R.M., K.K., L. Sugrue, F.S., E.O., K.H.N.), University of California San Francisco, California
- Department of Neurological Surgery (K.H.N.), University of California San Francisco, California
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Kim K, Diederich C, Narsinh K, Ozhinsky E. Motion-robust, multi-slice, real-time MR thermometry for MR-guided thermal therapy in abdominal organs. Int J Hyperthermia 2023; 40:2151649. [PMID: 36535967 PMCID: PMC10269483 DOI: 10.1080/02656736.2022.2151649] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 11/18/2022] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To develop an effective and practical reconstruction pipeline to achieve motion-robust, multi-slice, real-time MR thermometry for monitoring thermal therapy in abdominal organs. METHODS The application includes a fast spiral magnetic resonance imaging (MRI) pulse sequence and a real-time reconstruction pipeline based on multi-baseline proton resonance frequency shift (PRFS) method with visualization of temperature imaging. The pipeline supports multi-slice acquisition with minimal reconstruction lag. Simulations with a virtual motion phantom were performed to investigate the influence of the number of baselines and respiratory rate on the accuracy of temperature measurement. Phantom experiments with ultrasound heating were performed using a custom-made motion phantom to evaluate the performance of the pipeline. Lastly, experiments in healthy volunteers (N = 2) without heating were performed to evaluate the accuracy and stability of MR thermometry in abdominal organs (liver and kidney). RESULTS The multi-baseline approach with greater than 25 baselines resulted in minimal temperature errors in the simulation. Phantom experiments demonstrated a 713 ms update time for 3-slice acquisitions. Temperature maps with 30 baselines showed clear temperature distributions caused by ultrasound heating in the respiratory phantom. Finally, the pipeline was evaluated with physiologic motions in healthy volunteers without heating, which demonstrated the accuracy (root mean square error [RMSE]) of 1.23 ± 0.18 °C (liver) and 1.21 ± 0.17 °C (kidney) and precision of 1.13 ± 0.11 °C (liver) and 1.16 ± 0.15 °C (kidney) using 32 baselines. CONCLUSIONS The proposed real-time acquisition and reconstruction pipeline allows motion-robust, multi-slice, real-time temperature monitoring within the abdomen during free breathing.
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Affiliation(s)
- Kisoo Kim
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, USA
| | - Chris Diederich
- Department of Radiation Oncology, University of California, San Francisco, USA
| | - Kazim Narsinh
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, USA
| | - Eugene Ozhinsky
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, USA
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Alpers J, Hensen B, Rötzer M, Reimert DL, Gerlach T, Vick R, Gutberlet M, Wacker F, Hansen C. Comparison study of reconstruction algorithms for volumetric necrosis maps from 2D multi-slice GRE thermometry images. Sci Rep 2022; 12:11509. [PMID: 35799055 PMCID: PMC9263155 DOI: 10.1038/s41598-022-15712-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 06/28/2022] [Indexed: 12/24/2022] Open
Abstract
Cancer is a disease which requires a significant amount of careful medical attention. For minimally-invasive thermal ablation procedures, the monitoring of heat distribution is one of the biggest challenges. In this work, three approaches for volumetric heat map reconstruction (Delauney triangulation, minimum volume enclosing ellipsoids (MVEE) and splines) are presented based on uniformly distributed 2D MRI phase images rotated around the applicator’s main axis. We compare them with our previous temperature interpolation method with respect to accuracy, robustness and adaptability. All approaches are evaluated during MWA treatment on the same data sets consisting of 13 ex vivo bio protein phantoms, including six phantoms with simulated heat sink effects. Regarding accuracy, the DSC similarity results show a strong trend towards the MVEE (\documentclass[12pt]{minimal}
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\begin{document}$$0.80\pm 0.03$$\end{document}0.80±0.03) and the splines (\documentclass[12pt]{minimal}
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\begin{document}$$0.77\pm 0.04$$\end{document}0.77±0.04) method compared to the Delauney triangulation (\documentclass[12pt]{minimal}
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\begin{document}$$0.75\pm 0.02$$\end{document}0.75±0.02) or the temperature interpolation (\documentclass[12pt]{minimal}
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\begin{document}$$0.73\pm 0.07$$\end{document}0.73±0.07). Robustness is increased for all three approaches and the adaptability shows a significant trend towards the initial interpolation method and the splines. To overcome local inhomogeneities in the acquired data, the use of adaptive simulations should be considered in the future. In addition, the transfer to in vivo animal experiments should be considered to test for clinical applicability.
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Affiliation(s)
- Julian Alpers
- Faculty of Computer Science, Otto-von-Guericke University, 39106, Magdeburg, Germany. .,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany.
| | - Bennet Hensen
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, 30625, Hannover, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany
| | - Maximilian Rötzer
- Faculty of Computer Science, Otto-von-Guericke University, 39106, Magdeburg, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany
| | - Daniel L Reimert
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, 30625, Hannover, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany
| | - Thomas Gerlach
- Faculty of Electrical Engineering and Information Technologies, Otto-von-Guericke University, 39106, Magdeburg, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany
| | - Ralf Vick
- Faculty of Electrical Engineering and Information Technologies, Otto-von-Guericke University, 39106, Magdeburg, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany
| | - Marcel Gutberlet
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, 30625, Hannover, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany
| | - Frank Wacker
- Institute for Diagnostic and Interventional Radiology, Hannover Medical School, 30625, Hannover, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany
| | - Christian Hansen
- Faculty of Computer Science, Otto-von-Guericke University, 39106, Magdeburg, Germany.,Research Campus STIMULATE, Otto-von-Guericke University, 39106, Magdeburg, Germany
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Nayak KS, Lim Y, Campbell-Washburn AE, Steeden J. Real-Time Magnetic Resonance Imaging. J Magn Reson Imaging 2022; 55:81-99. [PMID: 33295674 PMCID: PMC8435094 DOI: 10.1002/jmri.27411] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 01/03/2023] Open
Abstract
Real-time magnetic resonance imaging (RT-MRI) allows for imaging dynamic processes as they occur, without relying on any repetition or synchronization. This is made possible by modern MRI technology such as fast-switching gradients and parallel imaging. It is compatible with many (but not all) MRI sequences, including spoiled gradient echo, balanced steady-state free precession, and single-shot rapid acquisition with relaxation enhancement. RT-MRI has earned an important role in both diagnostic imaging and image guidance of invasive procedures. Its unique diagnostic value is prominent in areas of the body that undergo substantial and often irregular motion, such as the heart, gastrointestinal system, upper airway vocal tract, and joints. Its value in interventional procedure guidance is prominent for procedures that require multiple forms of soft-tissue contrast, as well as flow information. In this review, we discuss the history of RT-MRI, fundamental tradeoffs, enabling technology, established applications, and current trends. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 1.
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Affiliation(s)
- Krishna S. Nayak
- Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California, USA,Address reprint requests to: K.S.N., 3740 McClintock Ave, EEB 400C, Los Angeles, CA 90089-2564, USA.
| | - Yongwan Lim
- Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California, USA
| | - Adrienne E. Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jennifer Steeden
- Institute of Cardiovascular Science, Centre for Cardiovascular Imaging, University College London, London, UK
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Franson D, Dupuis A, Gulani V, Griswold M, Seiberlich N. A System for Real-Time, Online Mixed-Reality Visualization of Cardiac Magnetic Resonance Images. J Imaging 2021; 7:jimaging7120274. [PMID: 34940741 PMCID: PMC8709155 DOI: 10.3390/jimaging7120274] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 11/16/2022] Open
Abstract
Image-guided cardiovascular interventions are rapidly evolving procedures that necessitate imaging systems capable of rapid data acquisition and low-latency image reconstruction and visualization. Compared to alternative modalities, Magnetic Resonance Imaging (MRI) is attractive for guidance in complex interventional settings thanks to excellent soft tissue contrast and large fields-of-view without exposure to ionizing radiation. However, most clinically deployed MRI sequences and visualization pipelines exhibit poor latency characteristics, and spatial integration of complex anatomy and device orientation can be challenging on conventional 2D displays. This work demonstrates a proof-of-concept system linking real-time cardiac MR image acquisition, online low-latency reconstruction, and a stereoscopic display to support further development in real-time MR-guided intervention. Data are acquired using an undersampled, radial trajectory and reconstructed via parallelized through-time radial generalized autocalibrating partially parallel acquisition (GRAPPA) implemented on graphics processing units. Images are rendered for display in a stereoscopic mixed-reality head-mounted display. The system is successfully tested by imaging standard cardiac views in healthy volunteers. Datasets comprised of one slice (46 ms), two slices (92 ms), and three slices (138 ms) are collected, with the acquisition time of each listed in parentheses. Images are displayed with latencies of 42 ms/frame or less for all three conditions. Volumetric data are acquired at one volume per heartbeat with acquisition times of 467 ms and 588 ms when 8 and 12 partitions are acquired, respectively. Volumes are displayed with a latency of 286 ms or less. The faster-than-acquisition latencies for both planar and volumetric display enable real-time 3D visualization of the heart.
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Affiliation(s)
- Dominique Franson
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA;
- Correspondence: (D.F.); (A.D.)
| | - Andrew Dupuis
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA;
- Correspondence: (D.F.); (A.D.)
| | - Vikas Gulani
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (V.G.); (N.S.)
| | - Mark Griswold
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA;
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Nicole Seiberlich
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA; (V.G.); (N.S.)
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Payne A, Merrill R, Minalga E, Hadley JR, Odeen H, Hofstetter LW, Johnson S, Tunon de Lara C, Auriol S, Recco S, Dumont E, Parker DL, Palussiere J. A Breast-Specific MR Guided Focused Ultrasound Platform and Treatment Protocol: First-in-Human Technical Evaluation. IEEE Trans Biomed Eng 2021; 68:893-904. [PMID: 32784128 PMCID: PMC7878578 DOI: 10.1109/tbme.2020.3016206] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE This paper presents and evaluates a breast-specific magnetic resonance guided focused ultrasound (MRgFUS) system. A first-in-human evaluation demonstrates the novel hardware, a sophisticated tumor targeting algorithm and a volumetric magnetic resonance imaging (MRI) protocol. METHODS At the time of submission, N = 10 patients with non-palpable T0 stage breast cancer have been treated with the breast MRgFUS system. The described tumor targeting algorithm is evaluated both with a phantom test and in vivo during the breast MRgFUS treatments. Treatments were planned and monitored using volumetric MR-acoustic radiation force imaging (MR-ARFI) and temperature imaging (MRTI). RESULTS Successful technical treatments were achieved in 80 % of the patients. All patients underwent the treatment with no sedation and 60 % of participants had analgesic support. The total MR treatment time ranged from 73 to 114 minutes. Mean error between desired and achieved targeting in a phantom was 2.9 ±1.8 mm while 6.2 ±1.9 mm was achieved in patient studies, assessed either with MRTI or MR-ARFI measurements. MRTI and MR-ARFI were successful in 60 % and 70 % of patients, respectively. CONCLUSION The targeting accuracy allows the accurate placement of the focal spot using electronic steering capabilities of the transducer. The use of both volumetric MRTI and MR-ARFI provides complementary treatment planning and monitoring information during the treatment, allowing the treatment of all breast anatomies, including homogeneously fatty breasts.
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Jiang R, Jia S, Qiao Y, Chen Q, Wen J, Liang D, Liu X, Zheng H, Zou C. Real-time volumetric MR thermometry using 3D echo-shifted sequence under an open source reconstruction platform. Magn Reson Imaging 2020; 70:22-28. [DOI: 10.1016/j.mri.2020.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 12/20/2022]
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10
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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: 70] [Impact Index Per Article: 14.0] [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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11
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Odéen H, Parker DL. Improved MR thermometry for laser interstitial thermotherapy. Lasers Surg Med 2019; 51:286-300. [PMID: 30645017 DOI: 10.1002/lsm.23049] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2018] [Indexed: 12/24/2022]
Abstract
OBJECTIVES To develop, test and evaluate improved 2D and 3D protocols for proton resonance frequency shift magnetic resonance temperature imaging (MRTI) of laser interstitial thermal therapy (LITT). The objective was to develop improved MRTI protocols in terms of temperature measurement precision and volume coverage compared to the 2D MRTI protocol currently used with a commercially available LITT system. METHODS Four different 2D protocols and four different 3D protocols were investigated. The 2D protocols used multi-echo readouts to prolong the total MR sampling time and hence the MRTI precision, without prolonging the total acquisition time. The 3D protocols provided volumetric thermometry by acquiring a slab of 12 contiguous slices in the same acquisition time as the 2D protocols. The study only considered readily available pulse sequences (Cartesian 2D and 3D gradient recalled echo and echo planar imaging [EPI]) and methods (partial Fourier and parallel imaging) to ensure wide availability and rapid clinical implementation across vendors and field strengths. In vivo volunteer studies were performed to investigate and compare MRTI precision and image quality. Phantom experiments with LITT heating were performed to investigate and compare MRTI precision and accuracy. Different coil setups were used in the in vivo studies to assess precision differences between using local (such as flex and head coils) and non-local (i.e., body coil) receive coils. Studies were performed at both 1.5 T and 3 T. RESULTS The improved 2D protocols provide up to a factor of two improvement in the MRTI precision in the same acquisition time, compared to the currently used clinical protocol. The 3D echo planar imaging protocols provide comparable precision as the currently used 2D clinical protocol, but over a substantially larger field of view, without increasing the acquisition time. As expected, local receive coils perform substantially better than the body coil, and 3 T provides better MRTI accuracy and precision than 1.5 T. 3D data can be zero-filled interpolated in all three dimensions (as opposed to just two dimensions for 2D data), reducing partial volume effects and measuring higher maximum temperature rises. CONCLUSIONS With the presented protocols substantially improved MRTI precision (for 2D imaging) or greatly improved field of view coverage (for 3D imaging) can be achieved in the same acquisition time as the currently used protocol. Only widely available pulse sequences and acquisition methods were investigated, which should ensure quick translation to the clinic. Lasers Surg. Med. 51:286-300, 2019. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Henrik Odéen
- Utah Center for Advanced Imaging Research, Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah
| | - Dennis L Parker
- Utah Center for Advanced Imaging Research, Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah
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12
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Allen SP, Feng X, Fielden SW, Meyer CH. Correcting image blur in spiral, retraced in/out (RIO) acquisitions using a maximized energy objective. Magn Reson Med 2018; 81:1806-1817. [PMID: 30421451 DOI: 10.1002/mrm.27541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/27/2018] [Accepted: 08/28/2018] [Indexed: 12/22/2022]
Abstract
PURPOSE Images acquired with spiral k-space trajectories can suffer from off-resonance image blur. Previous work showed that averaging 2 images acquired with a retraced, in/out (RIO) trajectory self-corrects image blur so long as off-resonant spins accrue less than 1 half-cycle of relative phase over the readout. Practical scenarios frequently exceed this threshold. Here, we derive and characterize a more-robust off-resonance image blur correction method for RIO acquisitions. METHODS Phantom and human volunteer data were acquired using a RIO trajectory with readout durations ranging from 4 to 60 ms. The resulting images were deblurred using 3 candidate methods: conventional linear correction of the component images; semiautomatic deblurring of the component images using an established minimized phase objective function; and semiautomatic deblurring of the average of the component images using a maximized energy objective function, derived below. Deblurring errors were estimated relative to images acquired with 4 ms readouts. RESULTS All 3 methods converged to similar solutions in cases where less than 2 and 4 cycles of phase accrued over the readout in in vivo and phantom images, respectively (<13 ms readout at 3T). Above this threshold, the linear and minimized phase methods introduced several errors. The maximized energy function provided accurate deblurring so long as less than 6 and 10 cycles of phase accrued over the readout in in vivo and phantom images, respectively (<34 ms readout at 3T). CONCLUSION The maximized energy objective function can accurately deblur RIO acquisitions over a wide spectrum of off resonance frequencies.
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Affiliation(s)
- Steven P Allen
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | - Xue Feng
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | - Samuel W Fielden
- Department of Imaging Science and Innovation, Geisinger, Danville, Pennsylvania
| | - Craig H Meyer
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia.,Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, Virginia
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