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Grutman T, Ilovitsh T. Dense speed-of-sound shift imaging for ultrasonic thermometry. Phys Med Biol 2023; 68:215004. [PMID: 37774710 DOI: 10.1088/1361-6560/acfec3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 09/29/2023] [Indexed: 10/01/2023]
Abstract
Objective. Develop a dense algorithm for calculating the speed-of-sound shift between consecutive acoustic acquisitions as a noninvasive means to evaluating temperature change during thermal ablation.Methods. An algorithm for dense speed-of-sound shift imaging (DSI) was developed to simultaneously incorporate information from the entire field of view using a combination of dense optical flow and inverse problem regularization, thus speeding up the calculation and introducing spatial agreement between pixels natively. Thermal ablation monitoring consisted of two main steps: pixel shift tracking using Farneback optical flow, and mathematical modeling of the relationship between the pixel displacement and temperature change as an inverse problem to find the speed-of-sound shift. A calibration constant translates from speed-of-sound shift to temperature change. The method performance was tested inex vivosamples and compared to standard thermal strain imaging (TSI) methods.Main results. Thermal ablation at a frequency of 2 MHz was applied to an agarose phantom that created a speed-of-sound shift measured by an L12-5 imaging transducer. A focal spot was reconstructed by solving the inverse problem. Next, a thermocouple measured the temperature rise during thermal ablation ofex vivochicken breast to calibrate the setup. Temperature changes between 3 °C and 15 °C was measured with high thermometry precision of less than 2 °C error for temperature changes as low as 8 °C. The DSI method outperformed standard TSI in both spatial coherence and runtime in high-intensity focused ultrasound-induced hyperthermia.Significance. Dense ultrasonic speed-of-sound shift imaging can successfully monitor the speed-of-sound shift introduced by thermal ablation. This technique is faster and more robust than current methods, and therefore can be used as a noninvasive, real time and cost-effective thermometry method, with high clinical applicability.
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Affiliation(s)
- Tal Grutman
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Tali Ilovitsh
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
- The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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Choquet K, Vappou J, Cabras P, Ishak O, Gangi A, Breton E. Magnetic Resonance Acoustic Radiation Force Imaging (MR-ARFI) for the monitoring of High Intensity Focused Ultrasound (HIFU) ablation in anisotropic tissue. MAGMA (NEW YORK, N.Y.) 2023; 36:737-747. [PMID: 36723689 DOI: 10.1007/s10334-023-01062-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 01/06/2023] [Accepted: 01/10/2023] [Indexed: 02/02/2023]
Abstract
OBJECTIVE We introduce a non-invasive MR-Acoustic Radiation Force Imaging (ARFI)-based elastography method that provides both the local shear modulus and temperature maps for the monitoring of High Intensity Focused Ultrasound (HIFU) therapy. MATERIALS AND METHODS To take tissue anisotropy into account, the local shear modulus μ is determined in selected radial directions around the focal spot by fitting the phase profiles to a linear viscoelastic model, including tissue-specific mechanical relaxation time τ. MR-ARFI was evaluated on a calibrated phantom, then applied to the monitoring of HIFU in a gel phantom, ex vivo and in vivo porcine muscle tissue, in parallel with MR-thermometry. RESULTS As expected, the shear modulus polar maps reflected the isotropy of phantoms and the anisotropy of muscle. In the HIFU monitoring experiments, both the shear modulus polar map and the thermometry map were updated with every pair of MR-ARFI phase images acquired with opposite MR-ARFI-encoding. The shear modulus was found to decrease (phantom and ex vivo) or increase (in vivo) during heating, before remaining steady during the cooling phase. The mechanical relaxation time, estimated pre- and post-HIFU, was found to vary in muscle tissue. DISCUSSION MR-ARFI allowed for monitoring of viscoelasticity changes around the HIFU focal spot even in anisotropic muscle tissue.
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Affiliation(s)
- Karine Choquet
- Université de Strasbourg, CNRS, ICube, UMR 7357, Strasbourg, France.
| | - Jonathan Vappou
- Université de Strasbourg, CNRS, ICube, UMR 7357, Strasbourg, France
| | - Paolo Cabras
- Université de Strasbourg, CNRS, ICube, UMR 7357, Strasbourg, France
- Image Guided Therapy, Pessac, France
| | - Ounay Ishak
- Université de Strasbourg, CNRS, ICube, UMR 7357, Strasbourg, France
| | - Afshin Gangi
- Université de Strasbourg, CNRS, ICube, UMR 7357, Strasbourg, France
- Department of Interventional Imaging, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Elodie Breton
- Université de Strasbourg, CNRS, ICube, UMR 7357, Strasbourg, France.
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Qi X, Sun J, Zhu J, Kong D, Roberts N, Dong Y, Huang X, He Q, Xing H, Gong Q. SPatiotemporal-ENcoded acoustic radiation force imaging of focused ultrasound. Front Hum Neurosci 2023; 17:1184629. [PMID: 37180550 PMCID: PMC10172656 DOI: 10.3389/fnhum.2023.1184629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 04/03/2023] [Indexed: 05/16/2023] Open
Abstract
Neuromodulation technology has provided novel therapeutic approaches for diseases caused by neural circuit dysfunction. Transcranial focused ultrasound (FU) is an emerging neuromodulation approach that combines noninvasiveness with relatively sharp focus, even in deep brain regions. It has numerous advantages such as high precision and good safety in neuromodulation, allowing for modulation of both peripheral and central nervous systems. To ensure accurate treatment targeting in FU neuromodulation, a magnetic resonance acoustic radiation force imaging (MR-ARFI) sequence is crucial for the visualization of the focal point. Currently, the commonly used 2D Spin Echo ARFI (2D SE-ARFI) sequence suffers from the long acquisition time, while the echo planar imaging ARFI (EPI-ARFI) sequence with a shorter acquisition time is vulnerable to the magnetic field inhomogeneities. To address these problems, we proposed a spatiotemporal-encoded acoustic radiation force imaging sequence (i.e., SE-SPEN-ARFI, shortened to SPEN-ARFI) in this study. The displacement at the focal spot obtained was highly consistent with that of the SE-ARFI sequence. Our research shows that SPEN-ARFI allows for rapid image acquisition and has less image distortions even under great field inhomogeneities. Therefore, a SPEN-ARFI sequence is a practical alternative for the treatment planning in ultrasound neuromodulation.
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Affiliation(s)
- Xu Qi
- College of Physics, Sichuan University, Chengdu, China
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, China
| | - Jiayu Sun
- Department of Radiology, West China Hospital of Sichuan University, Chengdu, China
| | - Jiayu Zhu
- Central Research Institute, United Imaging Healthcare Group, Shanghai, China
| | - Dechen Kong
- College of Physics, Sichuan University, Chengdu, China
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, China
| | - Neil Roberts
- College of Physics, Sichuan University, Chengdu, China
- Edinburgh Imaging and Centre for Reproductive Health (CFRH), Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Yijing Dong
- Central Research Institute, United Imaging Healthcare Group, Shanghai, China
| | - Xiaoqi Huang
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, China
- Research Unit of Psychoradiology, Chinese Academy of Medical Sciences, Chengdu, China
| | - Qiang He
- Brain Laboratory, United Imaging Research Institute of Innovative Medical Equipment, Shenzhen, China
| | - Haoyang Xing
- College of Physics, Sichuan University, Chengdu, China
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, China
- Research Unit of Psychoradiology, Chinese Academy of Medical Sciences, Chengdu, China
| | - Qiyong Gong
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, China
- Research Unit of Psychoradiology, Chinese Academy of Medical Sciences, Chengdu, China
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Li N, Gaur P, Quah K, Pauly KB. Improving in situ acoustic intensity estimates using MR acoustic radiation force imaging in combination with multifrequency MR elastography. Magn Reson Med 2022; 88:1673-1689. [PMID: 35762849 PMCID: PMC9439407 DOI: 10.1002/mrm.29309] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 04/28/2022] [Accepted: 04/30/2022] [Indexed: 11/08/2022]
Abstract
PURPOSE Magnetic resonance acoustic radiation force imaging (MR-ARFI) enables focal spot localization during nonablative transcranial ultrasound therapies. As the acoustic radiation force is proportional to the applied acoustic intensity, measured MR-ARFI displacements could potentially be used to estimate the acoustic intensity at the target. However, variable brain stiffness is an obstacle. The goal of this study was to develop and assess a method to accurately estimate the acoustic intensity at the focus using MR-ARFI displacements in combination with viscoelastic properties obtained with multifrequency MR elastography (MRE). METHODS Phantoms with a range of viscoelastic properties were fabricated, and MR-ARFI displacements were acquired within each phantom using multiple acoustic intensities. Voigt model parameters were estimated for each phantom based on storage and loss moduli measured using multifrequency MRE, and these were used to predict the relationship between acoustic intensity and measured displacement. RESULTS Using assumed viscoelastic properties, MR-ARFI displacements alone could not accurately estimate acoustic intensity across phantoms. For example, acoustic intensities were underestimated in phantoms stiffer than the assumed stiffness and overestimated in phantoms softer than the assumed stiffness. This error was greatly reduced using individualized viscoelasticity measurements obtained from MRE. CONCLUSION We demonstrated that viscoelasticity information from MRE could be used in combination with MR-ARFI displacements to obtain more accurate estimates of acoustic intensity. Additionally, Voigt model viscosity parameters were found to be predictive of the relaxation rate of each phantom's time-varying displacement response, which could be used to optimize patient-specific MR-ARFI pulse sequences.
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Affiliation(s)
- Ningrui Li
- Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Pooja Gaur
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Kristin Quah
- Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Kim Butts Pauly
- Department of Radiology, Stanford University, Stanford, California, USA
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Fite BZ, Wang J, Ghanouni P, Ferrara KW. A Review of Imaging Methods to Assess Ultrasound-Mediated Ablation. BME FRONTIERS 2022; 2022:9758652. [PMID: 35957844 PMCID: PMC9364780 DOI: 10.34133/2022/9758652] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 02/21/2022] [Indexed: 12/18/2022] Open
Abstract
Ultrasound ablation techniques are minimally invasive alternatives to surgical resection and have rapidly increased in use. The response of tissue to HIFU ablation differs based on the relative contributions of thermal and mechanical effects, which can be varied to achieve optimal ablation parameters for a given tissue type and location. In tumor ablation, similar to surgical resection, it is desirable to include a safety margin of ablated tissue around the entirety of the tumor. A factor in optimizing ablative techniques is minimizing the recurrence rate, which can be due to incomplete ablation of the target tissue. Further, combining focal ablation with immunotherapy is likely to be key for effective treatment of metastatic cancer, and therefore characterizing the impact of ablation on the tumor microenvironment will be important. Thus, visualization and quantification of the extent of ablation is an integral component of ablative procedures. The aim of this review article is to describe the radiological findings after ultrasound ablation across multiple imaging modalities. This review presents readers with a general overview of the current and emerging imaging methods to assess the efficacy of ultrasound ablative treatments.
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Affiliation(s)
- Brett Z. Fite
- Department of Radiology, Stanford University, Palo Alto, CA 94305, USA
| | - James Wang
- Department of Radiology, Stanford University, Palo Alto, CA 94305, USA
| | - Pejman Ghanouni
- Department of Radiology, Stanford University, Palo Alto, CA 94305, USA
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