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Sengupta S, Glenn A, Rogers BP. Prospective head motion correction at 3 Tesla with wireless NMR markers and ultrashort echo navigators. Magn Reson Imaging 2024; 114:110238. [PMID: 39276809 DOI: 10.1016/j.mri.2024.110238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 08/28/2024] [Accepted: 09/10/2024] [Indexed: 09/17/2024]
Abstract
PURPOSE Prospective motion correction (PMC) with inductively-coupled wireless NMR markers has been shown to be an effective plug-and-play method for dealing with head motion at 7 Tesla [29,30]. However, technical challenges such as one-to-one identification of three wireless markers, generation of hyper-intense marker artifacts and low marker peak SNR in the navigators has limited the adoption of this technique. The goal of this work is to introduce solutions to overcome these issues and extend this technique to PMC for brain imaging at 3 Tesla. METHODS PMC with 6 degrees of freedom (DOF) was implemented using a novel ∼8 ms, ultrashort echo time (UTE) navigator in concert with optimally chosen MnCl2 marker samples to minimize marker artifacts. Distinct head coil sensitivities were leveraged to enable identification and tracking of individual markers and a variable flip angle (VFA) scheme and real time filtering were used to boost marker SNR. PMC was performed in 3D T1 weighted brain imaging at 3 Tesla with voluntary head motions in adult volunteers. RESULTS PMC with wireless markers improved image quality in 3D T1 weighted images in all subjects compared to non-motion corrected images for similar motions with no noticeable marker artifacts. Precision of motion tracking was found to be in the range of 0.01-0.06 mm/degrees. Navigator execution had minimal impact on sequence duration. CONCLUSIONS Wireless NMR markers provide an accurate, calibration-free and economical option for 6 DOF PMC in brain imaging across field strengths. Challenges in this technique can be addressed by combining navigator design, sample selection and real time data processing strategies.
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Affiliation(s)
- Saikat Sengupta
- Vanderbilt University Institute of Imaging Science,Vanderbilt University Medical Center, Nashville, TN 37235, USA; Department of Radiology and Radiological Sciences,Vanderbilt University Medical Center, Nashville, TN 37235, USA.
| | - Antonio Glenn
- Department of Biomedical Engineering, Case Western Reserve University Cleveland, OH 44106, USA
| | - Baxter P Rogers
- Vanderbilt University Institute of Imaging Science,Vanderbilt University Medical Center, Nashville, TN 37235, USA; Department of Radiology and Radiological Sciences,Vanderbilt University Medical Center, Nashville, TN 37235, USA
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2
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Levakov G, Ganor S, Avidan G. Reliability and validity of brain-gastric phase synchronization. Hum Brain Mapp 2023; 44:4956-4966. [PMID: 37528686 PMCID: PMC10472921 DOI: 10.1002/hbm.26436] [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: 01/10/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 08/03/2023] Open
Abstract
Recent studies have reported that various brain regions, mainly sensory, unimodal regions, display phase synchronization with the stomach's slow (0.05 Hz) myoelectrical rhythm. These gastric-brain interactions have broad implications, from feeding behavior to functional gastrointestinal disorders. However, in contrast to other interoceptive signals (e.g., heart rate) and their relation to the brain, little is known about the reliability of these gastric-brain interactions, their robustness to artifacts such as motion, and whether they can be generalized to new samples. Here we examined these aspects in 43 subjects that had undergone multiple runs of concurrent electrogastrography (EGG), brain fMRI, and pulse oximetry. We also repeated all analyses in an open dataset of a highly sampled individual. We found a set of brain regions that were coupled with the EGG signal after controlling for non-grey matter (GM) signals, head motion, and cardiac artifacts. These regions exhibited significant overlap with previous work. However, we also showed that prior to confound regression, the spatial extent of the gastric network was largely overestimated. Finally, we found substantial test-retest reliability in both the brain and the gastric signals when estimated alone, but not for measures of gastric-brain synchrony. Together, these results provide methodological scaffolding for future research into brain-stomach interactions and for a better understanding of the role of the gastric network.
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Affiliation(s)
- Gidon Levakov
- Department of Cognitive and Brain SciencesBen‐Gurion University of the NegevBeer‐ShevaIsrael
| | - Shira Ganor
- Department of Cognitive and Brain SciencesBen‐Gurion University of the NegevBeer‐ShevaIsrael
| | - Galia Avidan
- Department of PsychologyBen‐Gurion University of the NegevBeer‐ShevaIsrael
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3
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Polak D, Hossbach J, Splitthoff DN, Clifford B, Lo WC, Tabari A, Lang M, Huang SY, Conklin J, Wald LL, Cauley S. Motion guidance lines for robust data consistency-based retrospective motion correction in 2D and 3D MRI. Magn Reson Med 2023; 89:1777-1790. [PMID: 36744619 PMCID: PMC10518424 DOI: 10.1002/mrm.29534] [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: 07/13/2022] [Revised: 10/06/2022] [Accepted: 10/31/2022] [Indexed: 02/07/2023]
Abstract
PURPOSE To develop a robust retrospective motion-correction technique based on repeating k-space guidance lines for improving motion correction in Cartesian 2D and 3D brain MRI. METHODS The motion guidance lines are inserted into the standard sequence orderings for 2D turbo spin echo and 3D MPRAGE to inform a data consistency-based motion estimation and reconstruction, which can be guided by a low-resolution scout. The extremely limited number of required guidance lines are repeated during each echo train and discarded in the final image reconstruction. Thus, integration within a standard k-space acquisition ordering ensures the expected image quality/contrast and motion sensitivity of that sequence. RESULTS Through simulation and in vivo 2D multislice and 3D motion experiments, we demonstrate that respectively 2 or 4 optimized motion guidance lines per shot enables accurate motion estimation and correction. Clinically acceptable reconstruction times are achieved through fully separable on-the-fly motion optimizations (˜1 s/shot) using standard scanner GPU hardware. CONCLUSION The addition of guidance lines to scout accelerated motion estimation facilitates robust retrospective motion correction that can be effectively introduced without perturbing standard clinical protocols and workflows.
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Affiliation(s)
- Daniel Polak
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Siemens Healthcare GmbH, Erlangen, Germany
| | | | | | | | | | - Azadeh Tabari
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Min Lang
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Susie Y. Huang
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
- Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - John Conklin
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Lawrence L. Wald
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
- Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Stephen Cauley
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
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4
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Levitt J, van der Kouwe A, Jeong H, Lewis LD, Bonmassar G. The MotoNet: A 3 Tesla MRI-Conditional EEG Net with Embedded Motion Sensors. SENSORS (BASEL, SWITZERLAND) 2023; 23:3539. [PMID: 37050598 PMCID: PMC10098760 DOI: 10.3390/s23073539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/20/2023] [Accepted: 03/23/2023] [Indexed: 06/19/2023]
Abstract
We introduce a new electroencephalogram (EEG) net, which will allow clinicians to monitor EEG while tracking head motion. Motion during MRI limits patient scans, especially of children with epilepsy. EEG is also severely affected by motion-induced noise, predominantly ballistocardiogram (BCG) noise due to the heartbeat. METHODS The MotoNet was built using polymer thick film (PTF) EEG leads and motion sensors on opposite sides in the same flex circuit. EEG/motion measurements were made with a standard commercial EEG acquisition system in a 3 Tesla (T) MRI. A Kalman filtering-based BCG correction tool was used to clean the EEG in healthy volunteers. RESULTS MRI safety studies in 3 T confirmed the maximum heating below 1 °C. Using an MRI sequence with spatial localization gradients only, the position of the head was linearly correlated with the average motion sensor output. Kalman filtering was shown to reduce the BCG noise and recover artifact-clean EEG. CONCLUSIONS The MotoNet is an innovative EEG net design that co-locates 32 EEG electrodes with 32 motion sensors to improve both EEG and MRI signal quality. In combination with custom gradients, the position of the net can, in principle, be determined. In addition, the motion sensors can help reduce BCG noise.
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Affiliation(s)
- Joshua Levitt
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - André van der Kouwe
- Athinoula A. Martinos Center for Biomedical Engineering, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Hongbae Jeong
- Athinoula A. Martinos Center for Biomedical Engineering, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Laura D. Lewis
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
- Athinoula A. Martinos Center for Biomedical Engineering, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Engineering, Massachusetts General Hospital, Charlestown, MA 02129, USA
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5
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Cui L, Song Y, Wang Y, Wang R, Wu D, Xie H, Li J, Yang G. Motion artifact reduction for magnetic resonance imaging with deep learning and k-space analysis. PLoS One 2023; 18:e0278668. [PMID: 36603007 DOI: 10.1371/journal.pone.0278668] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Accepted: 11/22/2022] [Indexed: 01/06/2023] Open
Abstract
Motion artifacts deteriorate the quality of magnetic resonance (MR) images. This study proposes a new method to detect phase-encoding (PE) lines corrupted by motion and remove motion artifacts in MR images. 67 cases containing 8710 slices of axial T2-weighted images from the IXI public dataset were split into three datasets, i.e., training (50 cases/6500 slices), validation (5/650), and test (12/1560) sets. First, motion-corrupted k-spaces and images were simulated using a pseudo-random sampling order and random motion tracks. A convolutional neural network (CNN) model was trained to filter the motion-corrupted images. Then, the k-space of the filtered image was compared with the motion-corrupted k-space line-by-line, to detect the PE lines affected by motion. Finally, the unaffected PE lines were used to reconstruct the final image using compressed sensing (CS). For the simulated images with 35%, 40%, 45%, and 50% unaffected PE lines, the mean peak signal-to-noise ratio (PSNRs) of resulting images (mean±standard deviation) were 36.129±3.678, 38.646±3.526, 40.426±3.223, and 41.510±3.167, respectively, and the mean structural similarity (SSIMs) were 0.950±0.046, 0.964±0.035, 0.975±0.025, and 0.979±0.023, respectively. For images with more than 35% PE lines unaffected by motion, images reconstructed with proposed algorithm exhibited better quality than those images reconstructed with CS using 35% under-sampled data (PSNR 37.678±3.261, SSIM 0.964±0.028). It was proved that deep learning and k-space analysis can detect the k-space PE lines affected by motion and CS can be used to reconstruct images from unaffected data, effectively alleviating the motion artifacts.
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Affiliation(s)
- Long Cui
- Department of Physics, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China
| | - Yang Song
- Department of Physics, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China
| | - Yida Wang
- Department of Physics, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China
| | - Rui Wang
- Department of Physics, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China
| | - Dongmei Wu
- Department of Physics, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China
| | - Haibin Xie
- Department of Physics, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China
| | - Jianqi Li
- Department of Physics, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China
| | - Guang Yang
- Department of Physics, Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China
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6
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Huang CFJ, Lin WL, Hwang SC, Yao C, Chang H, Chen YY, Kuo LW. A feasibility study of wireless inductively coupled surface coil for MR-guided high-intensity focused ultrasound ablation of rodents on clinical MRI systems. Sci Rep 2022; 12:21907. [PMID: 36536022 PMCID: PMC9763396 DOI: 10.1038/s41598-022-26452-z] [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: 06/06/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Recently, to conduct preclinical imaging research on clinical MRI systems has become an attractive alternative to researchers due to its wide availability, cost, and translational application to clinical human studies when compared to dedicated small animal, high-field preclinical MRI. However, insufficient signal-to-noise ratio (SNR) significantly degrades the applicability of those applications which require high SNR, e.g. magnetic resonance guided high-intensity focused ultrasound (MRgHIFU) treatment. This study introduces a wireless inductively coupled surface (WICS) coil design used on a clinical 3 T MRI system for MRgHIFU ablation. To evaluate the SNR improvement and temperature accuracy of WICS coil, the ex vivo experiments were performed on the pork tenderloins (n = 7) and the hind legs of deceased Sprague-Dawley rats (n = 5). To demonstrate the feasibility, the in vivo experiments were performed on the hind leg of Sprague-Dawley rat (n = 1). For all experiments, temperature measurements were performed before and during HIFU ablation. Temperature curves with and without WICS coil were compared to evaluate the temperature precision in ex vivo experiments. The use of WICS coil improves the temperature accuracy from 0.85 to 0.14 °C, demonstrating the feasibility of performing small animal MRgHIFU experiments using clinical 3 T MRI system with WICS coil.
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Affiliation(s)
- Chien-Feng Judith Huang
- grid.19188.390000 0004 0546 0241Department of Biomedical Engineering, National Taiwan University, Taipei, 100233 Taiwan ,grid.59784.370000000406229172Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, 35053 Taiwan
| | - Win-Li Lin
- grid.19188.390000 0004 0546 0241Department of Biomedical Engineering, National Taiwan University, Taipei, 100233 Taiwan ,grid.59784.370000000406229172Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, 35053 Taiwan
| | - San-Chao Hwang
- MBInsight Technology Corporation, New Taipei City, 236658 Taiwan
| | - Ching Yao
- MBInsight Technology Corporation, New Taipei City, 236658 Taiwan
| | - Hsu Chang
- MBInsight Technology Corporation, New Taipei City, 236658 Taiwan
| | - Yung-Yaw Chen
- grid.19188.390000 0004 0546 0241Department of Electrical Engineering, National Taiwan University, Taipei, 100233 Taiwan
| | - Li-Wei Kuo
- grid.59784.370000000406229172Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, 35053 Taiwan ,grid.19188.390000 0004 0546 0241Institute of Medical Device and Imaging, National Taiwan University, Taipei, 100233 Taiwan
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7
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Su H, Kwok KW, Cleary K, Iordachita I, Cavusoglu MC, Desai JP, Fischer GS. State of the Art and Future Opportunities in MRI-Guided Robot-Assisted Surgery and Interventions. PROCEEDINGS OF THE IEEE. INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS 2022; 110:968-992. [PMID: 35756185 PMCID: PMC9231642 DOI: 10.1109/jproc.2022.3169146] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Magnetic resonance imaging (MRI) can provide high-quality 3-D visualization of target anatomy, surrounding tissue, and instrumentation, but there are significant challenges in harnessing it for effectively guiding interventional procedures. Challenges include the strong static magnetic field, rapidly switching magnetic field gradients, high-power radio frequency pulses, sensitivity to electrical noise, and constrained space to operate within the bore of the scanner. MRI has a number of advantages over other medical imaging modalities, including no ionizing radiation, excellent soft-tissue contrast that allows for visualization of tumors and other features that are not readily visible by other modalities, true 3-D imaging capabilities, including the ability to image arbitrary scan plane geometry or perform volumetric imaging, and capability for multimodality sensing, including diffusion, dynamic contrast, blood flow, blood oxygenation, temperature, and tracking of biomarkers. The use of robotic assistants within the MRI bore, alongside the patient during imaging, enables intraoperative MR imaging (iMRI) to guide a surgical intervention in a closed-loop fashion that can include tracking of tissue deformation and target motion, localization of instrumentation, and monitoring of therapy delivery. With the ever-expanding clinical use of MRI, MRI-compatible robotic systems have been heralded as a new approach to assist interventional procedures to allow physicians to treat patients more accurately and effectively. Deploying robotic systems inside the bore synergizes the visual capability of MRI and the manipulation capability of robotic assistance, resulting in a closed-loop surgery architecture. This article details the challenges and history of robotic systems intended to operate in an MRI environment and outlines promising clinical applications and associated state-of-the-art MRI-compatible robotic systems and technology for making this possible.
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Affiliation(s)
- Hao Su
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695 USA
| | - Ka-Wai Kwok
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong
| | - Kevin Cleary
- Children's National Health System, Washington, DC 20010 USA
| | - Iulian Iordachita
- Laboratory for Computational Sensing and Robotics (LCSR), Johns Hopkins University, Baltimore, MD 21218 USA
| | - M Cenk Cavusoglu
- Department of Electrical, Computer, and Systems Engineering, Case Western Reserve University, Cleveland, OH 44106 USA
| | - Jaydev P Desai
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
| | - Gregory S Fischer
- Department of Robotics Engineering, Worcester Polytechnic Institute, Worcester, MA 01609 USA
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8
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Darnell D, Truong TK, Song AW. Recent Advances in Radio-Frequency Coil Technologies: Flexible, Wireless, and Integrated Coil Arrays. J Magn Reson Imaging 2022; 55:1026-1042. [PMID: 34324753 PMCID: PMC10494287 DOI: 10.1002/jmri.27865] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/19/2021] [Accepted: 07/19/2021] [Indexed: 12/25/2022] Open
Abstract
Radio-frequency (RF) coils are to magnetic resonance imaging (MRI) scanners what eyes are to the human body. Because of their critical importance, there have been constant innovations driving the rapid development of RF coil technologies. Over the past four decades, the breadth and depth of the RF coil technology evolution have far exceeded the space allowed for this review article. However, these past developments have laid the very foundation on which some of the recent technical breakthroughs are built upon. Here, we narrow our focus on some of the most recent RF coil advances, specifically, on flexible, wireless, and integrated coil arrays. To provide a detailed review, we discuss the theoretical underpinnings, experimental implementations, promising results, as well as future outlooks covering these exciting topics. These recent innovations have greatly improved patient comfort and ease of scan, while also increasing the signal-to-noise ratio, image resolution, temporal throughput, and diagnostic and treatment accuracy. Together with advances in other MRI subfields, they will undoubtedly continue to drive the field forward and lead us to an ever more exciting future. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Dean Darnell
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
| | - Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
| | - Allen W. Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina, USA
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9
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Andre JB, Amthor T, Hall CS, Gunn ML, Hoff MN, Cohen W, Beauchamp NJ. Correlating the Radiological Assessment of Patient Motion with the Incidence of Repeat Sequences Documented by Log Files. Curr Probl Diagn Radiol 2022; 51:534-539. [DOI: 10.1067/j.cpradiol.2022.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 01/05/2022] [Indexed: 11/22/2022]
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10
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van Niekerk A, Berglund J, Sprenger T, Norbeck O, Avventi E, Rydén H, Skare S. Control of a wireless sensor using the pulse sequence for prospective motion correction in brain MRI. Magn Reson Med 2021; 87:1046-1061. [PMID: 34453458 DOI: 10.1002/mrm.28994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/19/2021] [Accepted: 08/12/2021] [Indexed: 11/09/2022]
Abstract
PURPOSE To synchronize and pass information between a wireless motion-tracking device and a pulse sequence and show how this can be used to implement customizable navigator interleaving schemes that are part of the pulse sequence design. METHODS The device tracks motion by sampling the voltages induced in 3 orthogonal pickup coils by the changing gradient fields. These coils were modified to also detect RF-transmit events using a 3D RF-detection circuit. The device could then detect and decode a set RF signatures while ignoring excitations in the parent pulse sequence. A set of unique RF signatures were then paired with a collection of navigators and used to trigger readouts on the wireless device synchronous to the pulse sequence execution. Navigator interleaving schemes were then demonstrated in 3D RF-spoiled gradient echo, T1 -FLAIR (fluid-attenuated inversion recovery) PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction), and T2 -FLAIR PROPELLER pulse sequences. RESULTS Excitations in the parent pulse sequences were successfully rejected and the RF signatures successfully decoded. For the 3D gradient echo sequence, distortions were removed by interleaving flipped polarity navigators and taking the difference between consecutive readouts. The impact on scan duration was reduced by 54% by breaking up the navigators into smaller parts. Successful motion correction was performed using the PROPELLER pulse sequences in 3 Tesla and 1.5 Tesla MRI scanners without modifications to the device hardware or software. CONCLUSION The proposed RF signature-based triggering scheme enables complex interactions between the pulse sequence and a wireless device. Thus, enabling prospective motion correction that is repeatable, versatile, and minimally invasive with respect to hardware setup.
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Affiliation(s)
- Adam van Niekerk
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Johan Berglund
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Tim Sprenger
- MR Applied Science Laboratory Europe, GE Healthcare, Stockholm, Sweden
| | - Ola Norbeck
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden
| | - Enrico Avventi
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden
| | - Henric Rydén
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden
| | - Stefan Skare
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden
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11
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Kyme AZ, Fulton RR. Motion estimation and correction in SPECT, PET and CT. Phys Med Biol 2021; 66. [PMID: 34102630 DOI: 10.1088/1361-6560/ac093b] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 06/08/2021] [Indexed: 11/11/2022]
Abstract
Patient motion impacts single photon emission computed tomography (SPECT), positron emission tomography (PET) and X-ray computed tomography (CT) by giving rise to projection data inconsistencies that can manifest as reconstruction artifacts, thereby degrading image quality and compromising accurate image interpretation and quantification. Methods to estimate and correct for patient motion in SPECT, PET and CT have attracted considerable research effort over several decades. The aims of this effort have been two-fold: to estimate relevant motion fields characterizing the various forms of voluntary and involuntary motion; and to apply these motion fields within a modified reconstruction framework to obtain motion-corrected images. The aims of this review are to outline the motion problem in medical imaging and to critically review published methods for estimating and correcting for the relevant motion fields in clinical and preclinical SPECT, PET and CT. Despite many similarities in how motion is handled between these modalities, utility and applications vary based on differences in temporal and spatial resolution. Technical feasibility has been demonstrated in each modality for both rigid and non-rigid motion, but clinical feasibility remains an important target. There is considerable scope for further developments in motion estimation and correction, and particularly in data-driven methods that will aid clinical utility. State-of-the-art machine learning methods may have a unique role to play in this context.
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Affiliation(s)
- Andre Z Kyme
- School of Biomedical Engineering, The University of Sydney, Sydney, New South Wales, AUSTRALIA
| | - Roger R Fulton
- Sydney School of Health Sciences, The University of Sydney, Sydney, New South Wales, AUSTRALIA
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12
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Balasubramanian M, Mulkern RV, Neil JJ, Maier SE, Polimeni JR. Probing in vivo cortical myeloarchitecture in humans via line-scan diffusion acquisitions at 7 T with 250-500 micron radial resolution. Magn Reson Med 2020; 85:390-403. [PMID: 32738088 DOI: 10.1002/mrm.28419] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 06/15/2020] [Accepted: 06/18/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE The goal of this study was to measure diffusion signals within the cerebral cortex using the line-scan technique to achieve extremely high resolution in the radial direction (ie, perpendicular to the cortical surface) and to demonstrate the utility of these measurements for investigating laminar architecture in the living human brain. METHODS Line-scan diffusion data with 250-500 micron radial resolution were acquired at 7 T on 8 healthy volunteers, with each line prescribed perpendicularly to primary somatosensory cortex (S1) and primary motor cortex (M1). Apparent diffusion coefficients, fractional anisotropy values, and radiality indices were measured as a function of cortical depth. RESULTS In the deep layers of S1, we found evidence for high anisotropy and predominantly tangential diffusion, with low anisotropy observed in superficial S1. In M1, moderate anisotropy and predominantly radial diffusion was seen at almost all cortical depths. These patterns were consistent across subjects and were conspicuous without averaging data across different locations on the cortical sheet. CONCLUSION Our results are in accord with the myeloarchitecture of S1 and M1, known from prior histology studies: in S1, dense bands of tangential myelinated fibers run through the deep layers but not the superficial ones, and in M1, radial myelinated fibers are prominent at most cortical depths. This work therefore provides support for the idea that high-resolution diffusion signals, measured with the line-scan technique and receiving a boost in SNR at 7 T, may serve as a sensitive probe of in vivo laminar architecture.
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Affiliation(s)
- Mukund Balasubramanian
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Robert V Mulkern
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Jeffrey J Neil
- Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Stephan E Maier
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA.,Institute of Clinical Sciences, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jonathan R Polimeni
- Harvard Medical School, Boston, Massachusetts, USA.,Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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13
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Kyme AZ, Aksoy M, Henry DL, Bammer R, Maclaren J. Marker‐free optical stereo motion tracking for in‐bore MRI and PET‐MRI application. Med Phys 2020; 47:3321-3331. [DOI: 10.1002/mp.14199] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 04/12/2020] [Accepted: 04/15/2020] [Indexed: 11/09/2022] Open
Affiliation(s)
- Andre Z. Kyme
- School of Biomedical Engineering Faculty of Engineering and Computer Science University of Sydney Sydney Australia
- The Brain & Mind Centre University of Sydney Sydney Australia
| | - Murat Aksoy
- Department of Radiology Stanford University USA
| | - David L. Henry
- The Brain & Mind Centre University of Sydney Sydney Australia
- Faculty of Health Sciences University of Sydney Sydney Australia
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14
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Jordan CD, Thorne BRH, Wadhwa A, Losey AD, Ozhinsky E, Kondapavulur S, Fratello V, Moore T, Stillson C, Yee C, Watkins RD, Scott GC, Martin AJ, Zhang X, Wilson MW, Hetts SW. Wireless Resonant Circuits Printed Using Aerosol Jet Deposition for MRI Catheter Tracking. IEEE Trans Biomed Eng 2020; 67:876-882. [PMID: 31247538 PMCID: PMC6995687 DOI: 10.1109/tbme.2019.2922879] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Interventional magnetic resonance imaging (MRI) could allow for diagnosis and immediate treatment of ischemic stroke; however, such endovascular catheter-based procedures under MRI guidance are inherently difficult. One major challenge is tracking the tip of the catheter, as standard fabrication methods for building inductively coupled coil markers are rigid and bulky. Here, we report a new approach that uses aerosol jet deposition to three-dimensional (3-D) print an inductively coupled RF coil marker on a polymer catheter. Our approach enables lightweight conforming markers on polymer catheters and these low-profile markers allow the catheter to be more safely navigated in small caliber vessels. Prototype markers with an inductor with the geometry of a double helix are incorporated on catheters for in vitro studies, and we show that these markers exhibit good signal amplification. We report temperature measurements and, finally, demonstrate feasibility in a preliminary in vivo experiment. We provide material properties and electromagnetic simulation performance analysis. This paper presents fully aerosol jet-deposited and functional wireless resonant markers on polymer catheters for use in 3T clinical scanners.
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15
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Maknojia S, Churchill NW, Schweizer TA, Graham SJ. Resting State fMRI: Going Through the Motions. Front Neurosci 2019; 13:825. [PMID: 31456656 PMCID: PMC6700228 DOI: 10.3389/fnins.2019.00825] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 07/23/2019] [Indexed: 11/19/2022] Open
Abstract
Resting state functional magnetic resonance imaging (rs-fMRI) has become an indispensable tool in neuroscience research. Despite this, rs-fMRI signals are easily contaminated by artifacts arising from movement of the head during data collection. The artifacts can be problematic even for motions on the millimeter scale, with complex spatiotemporal properties that can lead to substantial errors in functional connectivity estimates. Effective correction methods must be employed, therefore, to distinguish true functional networks from motion-related noise. Research over the last three decades has produced numerous correction methods, many of which must be applied in combination to achieve satisfactory data quality. Subject instruction, training, and mild restraints are helpful at the outset, but usually insufficient. Improvements come from applying multiple motion correction algorithms retrospectively after rs-fMRI data are collected, although residual artifacts can still remain in cases of elevated motion, which are especially prevalent in patient populations. Although not commonly adopted at present, “real-time” correction methods are emerging that can be combined with retrospective methods and that promise better correction and increased rs-fMRI signal sensitivity. While the search for the ideal motion correction protocol continues, rs-fMRI research will benefit from good disclosure practices, such as: (1) reporting motion-related quality control metrics to provide better comparison between studies; and (2) including motion covariates in group-level analyses to limit the extent of motion-related confounds when studying group differences.
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Affiliation(s)
- Sanam Maknojia
- Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Nathan W Churchill
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada
| | - Tom A Schweizer
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada.,Division of Neurosurgery, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Institute of Biomaterials and Biomedical Engineering, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - S J Graham
- Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.,Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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16
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Afacan O, Wallace TE, Warfield SK. Retrospective correction of head motion using measurements from an electromagnetic tracker. Magn Reson Med 2019; 83:427-437. [PMID: 31400036 DOI: 10.1002/mrm.27934] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 06/25/2019] [Accepted: 07/15/2019] [Indexed: 11/06/2022]
Abstract
PURPOSE To investigate the feasibility of using an electromagnetic (EM) tracker to estimate rigid body head motion parameters, and using these measurements to retrospectively reduce motion artifacts. THEORY AND METHODS A clinically used MPRAGE sequence was modified to measure motion using the EM tracking system once per repetition time. A retrospective k-space based motion correction algorithm that corrects for phase ramps (translation in image domain) and rotation of 3D k-space (rotation in image domain) was developed, using the parameters recorded using an EM tracker. The accuracy of the EM tracker for the purpose of motion measurement and correction was tested in phantoms, volunteers, and pediatric patients. RESULTS Position localization was accurate to the order of 200 microns compared with registration localization in a phantom study. The quality of reconstructed images was assessed by computing the root mean square error, the structural similarity metric and average edge strength. Image quality improved consistently when motion correction was applied in both volunteer scans with deliberate head motion and in pediatric patient scans. In patients, the average edge strength improved significantly with retrospective motion correction, compared with images with no correction applied. CONCLUSIONS EM tracking was effective in measuring head motion in the MRI scanner with high accuracy, and enabled retrospective reconstruction to improve image quality by reducing motion artifacts.
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Affiliation(s)
- Onur Afacan
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Tess E Wallace
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Simon K Warfield
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
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17
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van Niekerk A, Meintjes E, van der Kouwe A. A Wireless Radio Frequency Triggered Acquisition Device (WRAD) for Self-Synchronised Measurements of the Rate of Change of the MRI Gradient Vector Field for Motion Tracking. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:1610-1621. [PMID: 30629498 PMCID: PMC7192240 DOI: 10.1109/tmi.2019.2891774] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In this paper, we present a device that is capable of wireless synchronization to the MRI pulse sequence time frame with sub-microsecond precision. This is achieved by detecting radio frequency pulses in the parent pulse sequence using a small resonant circuit. The device incorporates a 3-axis pickup coil, constructed using conventional printed circuit board (PCB) manufacturing techniques, to measure the rate of change of the gradient waveforms with respect to time. Using Maxwell's equations, assuming negligible rates of change of curl and divergence, a model of the expected gradient derivative (slew) vector field is presented. A 3-axis Hall effect magnetometer allows for the measurement of the direction of the static magnetic field in the device co-ordinate frame. By combining the magnetometer measurement with the pickup coil voltages and slew vector field model, the orientation and position can be determined to within a precision of 0.1 degrees and 0.1 mm, respectively, using a pulse series lasting 880 μs . The gradient pulses are designed to be sinusoidal, enabling the detection of a phase shift between the time frame of the pickup coil digitization circuit and the gradient amplifiers. The signal processing is performed by a low power micro-controller on the device and the results are transmitted out of the scanner bore using a low latency 2.4 GHz radio link. The device identified an unexpected 40 kHz oscillation relating to the pulse width modulation frequency of the gradient amplifiers that is predominantly in the direction of the static magnetic field. The proposed wireless radio frequency triggered acquisition device enables users to probe the scanner gradient slew vector field with minimal hardware set-up and shows promise for the future developments in the prospective motion correction.
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18
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Eschelbach M, Aghaeifar A, Bause J, Handwerker J, Anders J, Engel EM, Thielscher A, Scheffler K. Comparison of prospective head motion correction with NMR field probes and an optical tracking system. Magn Reson Med 2018; 81:719-729. [PMID: 30058220 DOI: 10.1002/mrm.27343] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 03/21/2018] [Accepted: 04/12/2018] [Indexed: 11/08/2022]
Abstract
PURPOSE The aim of this study was to compare prospective head motion correction and motion tracking abilities of two tracking systems: Active NMR field probes and a Moiré phase tracking camera system using an optical marker. METHODS Both tracking systems were used simultaneously on human subjects. The prospective head motion correction was compared in an MP2RAGE and a gradient echo sequence. In addition, the motion tracking trajectories for three subjects were compared against each other and their correlation and deviations were analyzed. RESULTS With both tracking systems motion artifacts were visibly reduced. The precision of the field probe system was on the order of 50 µm for translations and 0.03° for rotations while the camera's was approximately 5 µm and 0.007°. The comparison of the measured trajectories showed close correlation and an average absolute deviation below 500 µm and 0.5°. CONCLUSION This study presents the first in vivo comparison between NMR field probes and Moiré phase tracking. For the gradient echo images, the field probes had a similar motion correction performance as the optical tracking system. For the MP2RAGE measurement, however, the camera yielded better results. Still, both tracking systems substantially decreased image artifacts in the presence of subject motion. Thus, the motion tracking modality should be chosen according to the specific requirements of the experiment while considering the desired image resolution, refresh rate, and head coil constraints.
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Affiliation(s)
| | - Ali Aghaeifar
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
| | - Jonas Bause
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
| | - Jonas Handwerker
- Institute of Microelectronics, University of Ulm, Ulm, Germany.,Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany
| | - Jens Anders
- Institute of Microelectronics, University of Ulm, Ulm, Germany.,Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany
| | - Eva-Maria Engel
- Department of Prosthodontics, Center of Dentistry, Oral Medicine, and Maxillofacial Surgery, University Hospital Tuebingen, Germany
| | - Axel Thielscher
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.,Department of Electrical Engineering, Technical University of Denmark, Lyngby, Denmark.,DRCMR, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
| | - Klaus Scheffler
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.,Department for Biomedical Magnetic Resonance, University of Tuebingen, Tuebingen, Germany
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19
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Guo Z, Dong Z, Lee KH, Cheung CL, Fu HC, Ho JD, He H, Poon WS, Chan DTM, Kwok KW. Compact Design of a Hydraulic Driving Robot for Intraoperative MRI-Guided Bilateral Stereotactic Neurosurgery. IEEE Robot Autom Lett 2018. [DOI: 10.1109/lra.2018.2814637] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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Kyme AZ, Se S, Meikle SR, Fulton RR. Markerless motion estimation for motion-compensated clinical brain imaging. Phys Med Biol 2018; 63:105018. [PMID: 29637899 DOI: 10.1088/1361-6560/aabd48] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Motion-compensated brain imaging can dramatically reduce the artifacts and quantitative degradation associated with voluntary and involuntary subject head motion during positron emission tomography (PET), single photon emission computed tomography (SPECT) and computed tomography (CT). However, motion-compensated imaging protocols are not in widespread clinical use for these modalities. A key reason for this seems to be the lack of a practical motion tracking technology that allows for smooth and reliable integration of motion-compensated imaging protocols in the clinical setting. We seek to address this problem by investigating the feasibility of a highly versatile optical motion tracking method for PET, SPECT and CT geometries. The method requires no attached markers, relying exclusively on the detection and matching of distinctive facial features. We studied the accuracy of this method in 16 volunteers in a mock imaging scenario by comparing the estimated motion with an accurate marker-based method used in applications such as image guided surgery. A range of techniques to optimize performance of the method were also studied. Our results show that the markerless motion tracking method is highly accurate (<2 mm discrepancy against a benchmarking system) on an ethnically diverse range of subjects and, moreover, exhibits lower jitter and estimation of motion over a greater range than some marker-based methods. Our optimization tests indicate that the basic pose estimation algorithm is very robust but generally benefits from rudimentary background masking. Further marginal gains in accuracy can be achieved by accounting for non-rigid motion of features. Efficiency gains can be achieved by capping the number of features used for pose estimation provided that these features adequately sample the range of head motion encountered in the study. These proof-of-principle data suggest that markerless motion tracking is amenable to motion-compensated brain imaging and holds good promise for a practical implementation in clinical PET, SPECT and CT systems.
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Affiliation(s)
- Andre Z Kyme
- Faculty of Engineering and IT, University of Sydney, Sydney, Australia. Faculty of Health Sciences and Brain and Mind Centre, University of Sydney, Australia
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21
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Aranovitch A, Haeberlin M, Gross S, Dietrich BE, Wilm BJ, Brunner DO, Schmid T, Luechinger R, Pruessmann KP. Prospective motion correction with NMR markers using only native sequence elements. Magn Reson Med 2017; 79:2046-2056. [PMID: 28840611 DOI: 10.1002/mrm.26877] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/27/2017] [Accepted: 07/29/2017] [Indexed: 12/20/2022]
Abstract
PURPOSE To develop a method of tracking active NMR markers that requires no alterations of common imaging sequences and can be used for prospective motion correction (PMC) in brain MRI. METHODS Localization of NMR markers is achieved by acquiring short signal snippets in rapid succession and evaluating them jointly. To spatially encode the markers, snippets are timed such that signal phase is accrued during sequence intervals with suitably diverse gradient actuation. For motion tracking and PMC in brain imaging, the markers are mounted on a lightweight headset. PMC is then demonstrated with high-resolution T2 *- and T1 -weighted imaging sequences in the presence of instructed as well as residual unintentional head motion. RESULTS With both unaltered sequences, motion tracking was achieved with precisions on the order of 10 µm and 0.01° and temporal resolution of 48 and 39 ms, respectively. On this basis, PMC improved image quality significantly throughout. CONCLUSION The proposed approach permits high-precision motion tracking and PMC with standard imaging sequences. It does so without altering sequence design and thus overcomes a key hindrance to routine motion tracking with NMR markers. Magn Reson Med 79:2046-2057, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Alexander Aranovitch
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Maximilian Haeberlin
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Simon Gross
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Benjamin E Dietrich
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Bertram J Wilm
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - David O Brunner
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Thomas Schmid
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Roger Luechinger
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
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22
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Maclaren J, Aksoy M, Ooi MB, Zahneisen B, Bammer R. Prospective motion correction using coil-mounted cameras: Cross-calibration considerations. Magn Reson Med 2017; 79:1911-1921. [PMID: 28722314 DOI: 10.1002/mrm.26838] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/23/2017] [Accepted: 06/23/2017] [Indexed: 12/11/2022]
Abstract
PURPOSE Optical prospective motion correction substantially reduces sensitivity to motion in neuroimaging of human subjects. However, a major barrier to clinical deployment has been the time-consuming cross-calibration between the camera and MRI scanner reference frames. This work addresses this challenge. METHODS A single camera was mounted onto the head coil for tracking head motion. Two new methods were developed: (1) a rapid calibration method for camera-to-scanner cross-calibration using a custom-made tool incorporating wireless active markers, and (2) a calibration adjustment method to compensate for table motion between scans. Both methods were tested at 1.5T and 3T in vivo. Simulations were performed to determine the required mechanical tolerance for repositioning of the camera. RESULTS The rapid calibration method is completed in a short (<30 s) scan, which is carried out only once per installation. The calibration adjustment method requires no extra scan time and runs automatically whenever the system is used. The mechanical tolerance analysis indicates that most motion (90% reduction in voxel displacement) could be corrected even with far larger camera repositioning errors than are observed in practice. CONCLUSION The methods presented here allow calibration of sufficient quality to be carried out and maintained with no additional technologist workload. Magn Reson Med 79:1911-1921, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Julian Maclaren
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Murat Aksoy
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Melvyn B Ooi
- Department of Radiology, Stanford University, Stanford, California, USA.,Philips Healthcare, Gainesville, Florida, USA
| | | | - Roland Bammer
- Department of Radiology, Stanford University, Stanford, California, USA
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23
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van Niekerk A, van der Kouwe A, Meintjes E. A Method for Measuring Orientation Within a Magnetic Resonance Imaging Scanner Using Gravity and the Static Magnetic Field (VectOrient). IEEE TRANSACTIONS ON MEDICAL IMAGING 2017; 36:1129-1139. [PMID: 28129151 PMCID: PMC5637283 DOI: 10.1109/tmi.2017.2652502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In MRI brain imaging, subject motion limits obtainable image clarity. Due to the hardware layout of an MRI scanner, gradient excitations can be used to rapidly detect position. Orientation, however, is more difficult to detect and is commonly calculated by comparing the position measurements of multiple spatially constrained points to a reference dataset. The result is increased size of the apparatus the subject must wear, which can influence the imaging workflow. In optical based methods marker attachment sites are limited due to the line of sight requirement between the camera and marker, and an external reference frame is introduced. To address these challenges a method called VectOrient is proposed for orientation measurement that is based on vector observations of gravity and the MRI scanner's static magnetic field. A prototype device comprising of an accelerometer, magnetometer and angular rate sensor shows good MRI compatibility. Phantom scans of a pineapple with zero scanner specific calibration achieve comparable results to a rigid body registration algorithm with deviations less than 0.8 degrees over 28 degree changes in orientation. Dynamic performance shows potential for prospective motion correction as rapid changes in orientation (peak 20 degrees per second) can be corrected. The pulse sequence implemented achieves orientation updates with a latency estimated to be less than 12.7 ms, of which only a small fraction (<1 ms) is used for computing orientation from the raw sensor signals. The device is capable of quantifying subject respiration and heart rates. The proposed approach for orientation estimation could help address some limitations of existing methods such as orientation measurement range, temporal resolution, ease of use and marker placement.
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24
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Jorge J, Gretsch F, Gallichan D, Marques JP. Tracking discrete off-resonance markers with three spokes (trackDOTS) for compensation of head motion and B0
perturbations: Accuracy and performance in anatomical imaging. Magn Reson Med 2017; 79:160-171. [DOI: 10.1002/mrm.26654] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 02/03/2017] [Accepted: 02/03/2017] [Indexed: 01/29/2023]
Affiliation(s)
- João Jorge
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
| | - Frédéric Gretsch
- Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
| | - Daniel Gallichan
- Biomedical Imaging Research Center, École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
| | - José P. Marques
- Donders Institute; Radboud University; Nijmegen the Netherlands
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25
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Prospective motion correction for 3D pseudo-continuous arterial spin labeling using an external optical tracking system. Magn Reson Imaging 2017; 39:44-52. [PMID: 28137627 DOI: 10.1016/j.mri.2017.01.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 01/26/2017] [Accepted: 01/26/2017] [Indexed: 11/22/2022]
Abstract
Head motion is an unsolved problem in magnetic resonance imaging (MRI) studies of the brain. Real-time tracking using a camera has recently been proposed as a way to prevent head motion artifacts. As compared to navigator-based approaches that use MRI data to detect and correct motion, optical motion correction works independently of the MRI scanner, thus providing low-latency real-time motion updates without requiring any modifications to the pulse sequence. The purpose of this study was two-fold: 1) to demonstrate that prospective optical motion correction using an optical camera mitigates artifacts from head motion in three-dimensional pseudo-continuous arterial spin labeling (3D PCASL) acquisitions and 2) to assess the effect of latency differences between real-time optical motion tracking and navigator-style approaches (such as PROMO). An optical motion correction system comprising a single camera and a marker attached to the patient's forehead was used to track motion at a rate of 60fps. In the presence of motion, continuous tracking data from the optical system was used to update the scan plane in real-time during the 3D-PCASL acquisition. Navigator-style correction was simulated by using the tracking data from the optical system and performing updates only once per repetition time. Three normal volunteers and a patient were instructed to perform continuous and discrete head motion throughout the scan. Optical motion correction yielded superior image quality compared to uncorrected images or images using navigator-style correction. The standard deviations of pixel-wise CBF differences between reference and non-corrected, navigator-style-corrected and optical-corrected data were 14.28, 14.35 and 11.09mL/100g/min for continuous motion, and 12.42, 12.04 and 9.60mL/100g/min for discrete motion. Data obtained from the patient revealed that motion can obscure pathology and that application of optical prospective correction can successfully reveal the underlying pathology in the presence of head motion.
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26
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Zaitsev M, Akin B, LeVan P, Knowles BR. Prospective motion correction in functional MRI. Neuroimage 2016; 154:33-42. [PMID: 27845256 DOI: 10.1016/j.neuroimage.2016.11.014] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 11/04/2016] [Accepted: 11/05/2016] [Indexed: 10/20/2022] Open
Abstract
Due to the intrinsic low sensitivity of BOLD-fMRI long scanning is required. Subject motion during fMRI scans reduces statistical significance of the activation maps and increases the prevalence of false activations. Motion correction is therefore an essential tool for a successful fMRI data analysis. Retrospective motion correction techniques are now commonplace and are incorporated into a wide range of fMRI analysis toolboxes. These techniques are advantageous due to robustness, sequence independence and have minimal impact on the fMRI study setup. Retrospective techniques however, do not provide an accurate intra-volume correction, nor can these techniques correct for the spin-history effects. The application of prospective motion correction in fMRI appears to be effective in reducing false positives and increasing sensitivity when compared to retrospective techniques, particularly in the cases of substantial motion. Especially advantageous in this regard is the combination of prospective motion correction with dynamic distortion correction. Nevertheless, none of the recent methods are able to recover activations in presence of motion that are comparable to no-motion conditions, which motivates further research in the area of adaptive dynamic imaging.
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Affiliation(s)
- Maxim Zaitsev
- Department of Radiology - Medical Physics, University of Freiburg, Faculty of Medicine, University of Freiburg - Medical Centre, Freiburg, Germany.
| | - Burak Akin
- Department of Radiology - Medical Physics, University of Freiburg, Faculty of Medicine, University of Freiburg - Medical Centre, Freiburg, Germany
| | - Pierre LeVan
- Department of Radiology - Medical Physics, University of Freiburg, Faculty of Medicine, University of Freiburg - Medical Centre, Freiburg, Germany
| | - Benjamin R Knowles
- Department of Radiology - Medical Physics, University of Freiburg, Faculty of Medicine, University of Freiburg - Medical Centre, Freiburg, Germany
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27
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Afacan O, Erem B, Roby DP, Roth N, Roth A, Prabhu SP, Warfield SK. Evaluation of motion and its effect on brain magnetic resonance image quality in children. Pediatr Radiol 2016; 46:1728-1735. [PMID: 27488508 PMCID: PMC5083190 DOI: 10.1007/s00247-016-3677-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 06/02/2016] [Accepted: 07/20/2016] [Indexed: 11/26/2022]
Abstract
BACKGROUND Motion artifacts pose significant problems for the acquisition of MR images in pediatric populations. OBJECTIVE To evaluate temporal motion metrics in MRI scanners and their effect on image quality in pediatric populations in neuroimaging studies. MATERIALS AND METHODS We report results from a large pediatric brain imaging study that shows the effect of motion on MRI quality. We measured motion metrics in 82 pediatric patients, mean age 13.4 years, in a T1-weighted brain MRI scan. As a result of technical difficulties, 5 scans were not included in the subsequent analyses. A radiologist graded the images using a 4-point scale ranging from clinically non-diagnostic because of motion artifacts to no motion artifacts. We used these grades to correlate motion parameters such as maximum motion, mean displacement from a reference point, and motion-free time with image quality. RESULTS Our results show that both motion-free time (as a ratio of total scan time) and average displacement from a position at a fixed time (when the center of k-space was acquired) were highly correlated with image quality, whereas maximum displacement was not as good a predictor. Among the 77 patients whose motion was measured successfully, 17 had average displacements of greater than 0.5 mm, and 11 of those (14.3%) resulted in non-diagnostic images. Similarly, 14 patients (18.2%) had less than 90% motion-free time, which also resulted in non-diagnostic images. CONCLUSION We report results from a large pediatric study to show how children and young adults move in the MRI scanner and the effect that this motion has on image quality. The results will help the motion-correction community in better understanding motion patterns in pediatric populations and how these patterns affect MR image quality.
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Affiliation(s)
- Onur Afacan
- Department of Radiology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Ave., WB215, Boston, MA, 02115, USA.
| | - Burak Erem
- Department of Radiology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Ave., WB215, Boston, MA, 02115, USA
| | - Diona P Roby
- Department of Radiology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Ave., WB215, Boston, MA, 02115, USA
| | - Noam Roth
- Robin Medical Inc., Baltimore, MD, USA
| | - Amir Roth
- Robin Medical Inc., Baltimore, MD, USA
| | - Sanjay P Prabhu
- Department of Radiology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Ave., WB215, Boston, MA, 02115, USA
| | - Simon K Warfield
- Department of Radiology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Ave., WB215, Boston, MA, 02115, USA
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Ali R, Goubran M, Choudhri O, Zeineh MM. Seven-Tesla MRI and neuroimaging biomarkers for Alzheimer's disease. Neurosurg Focus 2016; 39:E4. [PMID: 26646928 DOI: 10.3171/2015.9.focus15326] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The goal of this paper was to review the effectiveness of using 7-T MRI to study neuroimaging biomarkers for Alzheimer's disease (AD). The authors reviewed the literature for articles published to date on the use of 7-T MRI to study AD. Thus far, there are 3 neuroimaging biomarkers for AD that have been studied using 7-T MRI in AD tissue: 1) neuroanatomical atrophy; 2) molecular characterization of hypointensities; and 3) microinfarcts. Seven-Tesla MRI has had mixed results when used to study the 3 aforementioned neuroimaging biomarkers for AD. First, in the detection of neuroanatomical atrophy, 7-T MRI has exciting potential. Historically, noninvasive imaging of neuroanatomical atrophy during AD has been limited by suboptimal resolution. However, now there is compelling evidence that the high resolution of 7-T MRI may help overcome this hurdle. Second, in detecting the characterization of hypointensities, 7-T MRI has had varied success. PET scans will most likely continue to lead in the noninvasive imaging of amyloid plaques; however, there is emerging evidence that 7-T MRI can accurately detect iron deposits within activated microglia, which may help shed light on the role of the immune system in AD pathogenesis. Finally, in the detection of microinfarcts, 7-T MRI may also play a promising role, which may help further elucidate the relationship between cerebrovascular health and AD progression.
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Affiliation(s)
| | - Maged Goubran
- Radiology, Stanford University School of Medicine, Stanford, California
| | | | - Michael M Zeineh
- Radiology, Stanford University School of Medicine, Stanford, California
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Waszak M, Falkovskiy P, Hilbert T, Bonnier G, Maréchal B, Meuli R, Gruetter R, Kober T, Krueger G. Prospective head motion correction using FID-guided on-demand image navigators. Magn Reson Med 2016; 78:193-203. [DOI: 10.1002/mrm.26364] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 06/19/2016] [Accepted: 07/11/2016] [Indexed: 12/30/2022]
Affiliation(s)
- Maryna Waszak
- Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG; Lausanne Switzerland
- LTS5, École Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
| | - Pavel Falkovskiy
- Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG; Lausanne Switzerland
- LTS5, École Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
| | - Tom Hilbert
- Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG; Lausanne Switzerland
- LTS5, École Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
| | - Guillaume Bonnier
- Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG; Lausanne Switzerland
- LTS5, École Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
| | - Bénédicte Maréchal
- Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG; Lausanne Switzerland
- LTS5, École Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
| | - Reto Meuli
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
| | - Rolf Gruetter
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
- Centre d'Imagerie BioMedicale (CIBM), École Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology, University of Geneva; Geneva Switzerland
| | - Tobias Kober
- Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG; Lausanne Switzerland
- LTS5, École Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
| | - Gunnar Krueger
- LTS5, École Polytechnique Fédérale de Lausanne (EPFL); Lausanne Switzerland
- Department of Radiology, University Hospital (CHUV); Lausanne Switzerland
- Siemens Medical Solutions USA, Inc; Boston MA USA
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Svedin BT, Beck MJ, Hadley JR, Merrill R, de Bever JT, Bolster BD, Payne A, Parker DL. Focal point determination in magnetic resonance-guided focused ultrasound using tracking coils. Magn Reson Med 2016; 77:2424-2430. [PMID: 27418429 DOI: 10.1002/mrm.26294] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 05/07/2016] [Accepted: 05/11/2016] [Indexed: 11/08/2022]
Abstract
PURPOSE To develop a method for rapid prediction of the geometric focus location in MR coordinates of a focused ultrasound (US) transducer with arbitrary position and orientation without sonicating. METHODS Three small tracker coil circuits were designed, constructed, attached to the transducer housing of a breast-specific MR-guided focused US (MRgFUS) system with 5 degrees of freedom, and connected to receiver channel inputs of an MRI scanner. A one-dimensional sequence applied in three orthogonal directions determined the position of each tracker, which was then corrected for gradient nonlinearity. In a calibration step, low-level heating located the US focus in one transducer position orientation where the tracker positions were also known. Subsequent US focus locations were determined from the isometric transformation of the trackers. The accuracy of this method was verified by comparing the tracking coil predictions to thermal center of mass calculated using MR thermometry data acquired at 16 different transducer positions for MRgFUS sonications in a homogeneous gelatin phantom. RESULTS The tracker coil predicted focus was an average distance of 2.1 ± 1.1 mm from the thermal center of mass. The one-dimensional locator sequence and prediction calculations took less than 1 s to perform. CONCLUSION This technique accurately predicts the geometric focus for a transducer with arbitrary position and orientation without sonicating. Magn Reson Med 77:2424-2430, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Bryant T Svedin
- Radiology Department, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
| | - Michael J Beck
- Radiology Department, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
| | - J Rock Hadley
- Radiology Department, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
| | - Robb Merrill
- Radiology Department, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
| | - Joshua T de Bever
- Radiology Department, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
| | - Bradley D Bolster
- Radiology Department, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
| | - Allison Payne
- Radiology Department, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
| | - Dennis L Parker
- Radiology Department, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
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31
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Godenschweger F, Kägebein U, Stucht D, Yarach U, Sciarra A, Yakupov R, Lüsebrink F, Schulze P, Speck O. Motion correction in MRI of the brain. Phys Med Biol 2016; 61:R32-56. [PMID: 26864183 DOI: 10.1088/0031-9155/61/5/r32] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Subject motion in MRI is a relevant problem in the daily clinical routine as well as in scientific studies. Since the beginning of clinical use of MRI, many research groups have developed methods to suppress or correct motion artefacts. This review focuses on rigid body motion correction of head and brain MRI and its application in diagnosis and research. It explains the sources and types of motion and related artefacts, classifies and describes existing techniques for motion detection, compensation and correction and lists established and experimental approaches. Retrospective motion correction modifies the MR image data during the reconstruction, while prospective motion correction performs an adaptive update of the data acquisition. Differences, benefits and drawbacks of different motion correction methods are discussed.
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Affiliation(s)
- F Godenschweger
- Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Germany
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32
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Hoffmann M, Mada M, Carpenter TA, Sawiak SJ, Williams GB. Additional sampling directions improve detection range of wireless radiofrequency probes. Magn Reson Med 2015; 76:913-8. [PMID: 26418189 PMCID: PMC5025722 DOI: 10.1002/mrm.25993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 08/24/2015] [Accepted: 08/29/2015] [Indexed: 11/10/2022]
Abstract
Purpose While MRI is enhancing our knowledge about the structure and function of the human brain, subject motion remains a problem in many clinical applications. Recently, the use of wireless radiofrequency markers with three one‐dimensional (1D) navigators for prospective correction was demonstrated. This method is restricted in the range of motion that can be corrected, however, because of limited information in the 1D readouts. Methods Here, the limitation of techniques for disambiguating marker locations was investigated. It was shown that including more sampling directions extends the tracking range for head rotations. The efficiency of trading readout resolution for speed was explored. Results Tracking of head rotations was demonstrated from −19.2 to 34.4°, −2.7 to 10.0°, and −60.9 to 70.9° in the x‐, y‐, and z‐directions, respectively. In the presence of excessive head motion, the deviation of marker estimates from SPM8 was reduced by 17.1% over existing three‐projection methods. This was achieved by using an additional seven directions, extending the time needed for readouts by a factor of 3.3. Much of this increase may be circumvented by reducing resolution, without compromising accuracy. Conclusion Including additional sampling directions extends the range in which markers can be used, for patients who move a lot. Magn Reson Med 76:913–918, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Malte Hoffmann
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Marius Mada
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - T Adrian Carpenter
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Stephen J Sawiak
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom.,Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom
| | - Guy B Williams
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
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Andre JB, Bresnahan BW, Mossa-Basha M, Hoff MN, Smith CP, Anzai Y, Cohen WA. Toward Quantifying the Prevalence, Severity, and Cost Associated With Patient Motion During Clinical MR Examinations. J Am Coll Radiol 2015; 12:689-95. [PMID: 25963225 DOI: 10.1016/j.jacr.2015.03.007] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/04/2015] [Indexed: 11/19/2022]
Abstract
PURPOSE To assess the prevalence, severity, and cost estimates associated with motion artifacts identified on clinical MR examinations, with a focus on the neuroaxis. METHODS A retrospective review of 1 randomly selected full calendar week of MR examinations (April 2014) was conducted for the detection of significant motion artifacts in examinations performed at a single institution on 3 different MR scanners. A base-case cost estimate was computed from recently available institutional data, and correlated with sequence time and severity of motion artifacts. RESULTS A total of 192 completed clinical examinations were reviewed. Significant motion artifacts were identified on sequences in 7.5% of outpatient and 29.4% of inpatient and/or emergency department MR examinations. The prevalence of repeat sequences was 19.8% of total MRI examinations. The base-case cost estimate yielded a potential cost to the hospital of $592 per hour in lost revenue due to motion artifacts. Potential institutional average costs borne (revenue forgone) of approximately $115,000 per scanner per year may affect hospitals, owing to motion artifacts (univariate sensitivity analysis suggested a lower bound of $92,600, and an upper bound of $139,000). CONCLUSIONS Motion artifacts represent a frequent cause of MR image degradation, particularly for inpatient and emergency department patients, resulting in substantial costs to the radiology department. Greater attention and resources should be directed toward providing practical solutions to this dilemma.
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Affiliation(s)
- Jalal B Andre
- Department of Radiology, University of Washington, Seattle, Washington.
| | - Brian W Bresnahan
- Department of Radiology, University of Washington, Seattle, Washington
| | | | - Michael N Hoff
- Department of Radiology, University of Washington, Seattle, Washington
| | - C Patrick Smith
- Department of Radiology, Harborview Medical Center, Seattle, Washington
| | - Yoshimi Anzai
- Department of Radiology, University of Washington, Seattle, Washington
| | - Wendy A Cohen
- Department of Radiology, University of Washington, Seattle, Washington
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34
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Zahneisen B, Ernst T. Homogeneous coordinates in motion correction. Magn Reson Med 2015; 75:274-9. [PMID: 25648318 DOI: 10.1002/mrm.25552] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 10/01/2014] [Accepted: 11/07/2014] [Indexed: 11/09/2022]
Abstract
PURPOSE Prospective motion correction for MRI and other imaging modalities are commonly based on the assumption of affine motion, i.e., rotations, shearing, scaling and translations. In addition it often involves transformations between different reference frames, especially for applications with an external tracking device. The goal of this work is to develop a computational framework for motion correction based on homogeneous transforms. THEORY AND METHODS The homogeneous representation of affine transformations uses 4 × 4 transformation matrices applied to four-dimensional augmented vectors. It is demonstrated how homogenous transforms can be used to describe the motion of slice objects during an MRI scan. Furthermore, we extend the concept of homogeneous transforms to gradient and k-space vectors, and show that the fourth dimension of an augmented k-space vector encodes the complex phase of the corresponding signal sample due to translations. RESULTS The validity of describing motion tracking in real space and k-space using homogeneous transformations only is demonstrated on phantom experiments. CONCLUSION Homogeneous transformations allows for a conceptually simple, consistent and computationally efficient theoretical framework for motion correction applications.
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Affiliation(s)
- Benjamin Zahneisen
- University of Hawaii, Department of Medicine, John A. Burns School of Medicine, Honolulu, Hawaii, USA
| | - Thomas Ernst
- University of Hawaii, Department of Medicine, John A. Burns School of Medicine, Honolulu, Hawaii, USA
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35
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Zaitsev M, Maclaren J, Herbst M. Motion artifacts in MRI: A complex problem with many partial solutions. J Magn Reson Imaging 2015; 42:887-901. [PMID: 25630632 DOI: 10.1002/jmri.24850] [Citation(s) in RCA: 356] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 12/22/2014] [Indexed: 01/29/2023] Open
Abstract
Subject motion during magnetic resonance imaging (MRI) has been problematic since its introduction as a clinical imaging modality. While sensitivity to particle motion or blood flow can be used to provide useful image contrast, bulk motion presents a considerable problem in the majority of clinical applications. It is one of the most frequent sources of artifacts. Over 30 years of research have produced numerous methods to mitigate or correct for motion artifacts, but no single method can be applied in all imaging situations. Instead, a "toolbox" of methods exists, where each tool is suitable for some tasks, but not for others. This article reviews the origins of motion artifacts and presents current mitigation and correction methods. In some imaging situations, the currently available motion correction tools are highly effective; in other cases, appropriate tools still need to be developed. It seems likely that this multifaceted approach will be what eventually solves the motion sensitivity problem in MRI, rather than a single solution that is effective in all situations. This review places a strong emphasis on explaining the physics behind the occurrence of such artifacts, with the aim of aiding artifact detection and mitigation in particular clinical situations.
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Affiliation(s)
- Maxim Zaitsev
- Department of Radiology, University Medical Centre Freiburg, Freiburg, Germany
| | - Julian Maclaren
- Department of Radiology, University Medical Centre Freiburg, Freiburg, Germany.,Department of Radiology, Stanford University, Stanford, California, USA
| | - Michael Herbst
- Department of Radiology, University Medical Centre Freiburg, Freiburg, Germany.,University of Hawaii, Department of Medicine, John A. Burns School of Medicine, Honolulu, Hawaii, USA
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36
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Huang C, Ackerman JL, Petibon Y, Brady TJ, El Fakhri G, Ouyang J. MR-based motion correction for PET imaging using wired active MR microcoils in simultaneous PET-MR: phantom study. Med Phys 2014; 41:041910. [PMID: 24694141 DOI: 10.1118/1.4868457] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Artifacts caused by head motion present a major challenge in brain positron emission tomography (PET) imaging. The authors investigated the feasibility of using wired active MR microcoils to track head motion and incorporate the measured rigid motion fields into iterative PET reconstruction. METHODS Several wired active MR microcoils and a dedicated MR coil-tracking sequence were developed. The microcoils were attached to the outer surface of an anthropomorphic(18)F-filled Hoffman phantom to mimic a brain PET scan. Complex rotation/translation motion of the phantom was induced by a balloon, which was connected to a ventilator. PET list-mode and MR tracking data were acquired simultaneously on a PET-MR scanner. The acquired dynamic PET data were reconstructed iteratively with and without motion correction. Additionally, static phantom data were acquired and used as the gold standard. RESULTS Motion artifacts in PET images were effectively removed by wired active MR microcoil based motion correction. Motion correction yielded an activity concentration bias ranging from -0.6% to 3.4% as compared to a bias ranging from -25.0% to 16.6% if no motion correction was applied. The contrast recovery values were improved by 37%-156% with motion correction as compared to no motion correction. The image correlation (mean ± standard deviation) between the motion corrected (uncorrected) images of 20 independent noise realizations and static reference was R(2) = 0.978 ± 0.007 (0.588 ± 0.010, respectively). CONCLUSIONS Wired active MR microcoil based motion correction significantly improves brain PET quantitative accuracy and image contrast.
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Affiliation(s)
- Chuan Huang
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Jerome L Ackerman
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Yoann Petibon
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Thomas J Brady
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Georges El Fakhri
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Jinsong Ouyang
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
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Hegde SS, Zhang Y, Bottomley PA. Acceleration and motion-correction techniques for high-resolution intravascular MRI. Magn Reson Med 2014; 74:452-61. [PMID: 25163750 DOI: 10.1002/mrm.25436] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 08/06/2014] [Accepted: 08/11/2014] [Indexed: 11/07/2022]
Abstract
PURPOSE High-resolution intravascular (IV) MRI is susceptible to degradation from physiological motion and requires high frame-rates for true endoscopy. Traditional cardiac-gating techniques compromise efficiency by reducing the effective scan rate. Here we test whether compressed sensing (CS) reconstruction and ungated motion-compensation using projection shifting, could provide faster motion-suppressed, IVMRI. THEORY AND METHODS CS reconstruction is developed for undersampled Cartesian and radial imaging using a new IVMRI-specific cost function to effectively increase imaging speed. A new motion correction method is presented wherein individual IVMRI projections are shifted based on the IVMRI detector's intrinsic amplitude and phase properties. The methods are tested at 3 Tesla (T) in fruit, human vessel specimens, and a rabbit aorta in vivo. Images are compared using structural-similarity and "spokal variation" indices. RESULTS Although some residual artifacts persisted, CS acceleration and radial motion compensation strategies reduced motion artifact in vitro and in vivo, allowing effective accelerations of up to eight-fold at 200-300 µm resolution. CONCLUSION The 3T IVMRI detectors are well-suited to CS and motion correction strategies based on their intrinsic radially-sparse sensitivity profiles and high signal-to-noise ratios.
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Affiliation(s)
- Shashank Sathyanarayana Hegde
- Russell H. Morgan Department of Radiology & Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA
| | - Yi Zhang
- Russell H. Morgan Department of Radiology & Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA.,Department of Electrical & Computer Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Paul A Bottomley
- Russell H. Morgan Department of Radiology & Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA.,Department of Electrical & Computer Engineering, Johns Hopkins University, Baltimore, Maryland, USA
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Huang C, Ackerman JL, Petibon Y, Normandin MD, Brady TJ, El Fakhri G, Ouyang J. Motion compensation for brain PET imaging using wireless MR active markers in simultaneous PET-MR: phantom and non-human primate studies. Neuroimage 2014; 91:129-37. [PMID: 24418501 DOI: 10.1016/j.neuroimage.2013.12.061] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 12/16/2013] [Accepted: 12/30/2013] [Indexed: 11/19/2022] Open
Abstract
Brain PET scanning plays an important role in the diagnosis, prognostication and monitoring of many brain diseases. Motion artifacts from head motion are one of the major hurdles in brain PET. In this work, we propose to use wireless MR active markers to track head motion in real time during a simultaneous PET-MR brain scan and incorporate the motion measured by the markers in the listmode PET reconstruction. Several wireless MR active markers and a dedicated fast MR tracking pulse sequence module were built. Data were acquired on an ACR Flangeless PET phantom with multiple spheres and a non-human primate with and without motion. Motions of the phantom and monkey's head were measured with the wireless markers using a dedicated MR tracking sequence module. The motion PET data were reconstructed using list-mode reconstruction with and without motion correction. Static reference was used as gold standard for quantitative analysis. The motion artifacts, which were prominent on the images without motion correction, were eliminated by the wireless marker based motion correction in both the phantom and monkey experiments. Quantitative analysis was performed on the phantom motion data from 24 independent noise realizations. The reduction of bias of sphere-to-background PET contrast by active marker based motion correction ranges from 26% to 64% and 17% to 25% for hot (i.e., radioactive) and cold (i.e., non-radioactive) spheres, respectively. The motion correction improved the channelized Hotelling observer signal-to-noise ratio of the spheres by 1.2 to 6.9 depending on their locations and sizes. The proposed wireless MR active marker based motion correction technique removes the motion artifacts in the reconstructed PET images and yields accurate quantitative values.
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Affiliation(s)
- Chuan Huang
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Jerome L Ackerman
- Department of Radiology, Harvard Medical School, Boston, MA 02115, USA; Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA.
| | - Yoann Petibon
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, MA 02114, USA; Laboratoire d'imagerie fonctionnelle (LIF), UMRS-678, INSERM, Université Pierre et Marie Curie, CHU Pitié-Salpêtrière, Paris, France.
| | - Marc D Normandin
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Thomas J Brady
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Georges El Fakhri
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Jinsong Ouyang
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Radiology, Harvard Medical School, Boston, MA 02115, USA.
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Sengupta S, Tadanki S, Gore JC, Welch EB. Prospective real-time head motion correction using inductively coupled wireless NMR probes. Magn Reson Med 2013; 72:971-85. [PMID: 24243810 DOI: 10.1002/mrm.25001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 09/14/2013] [Accepted: 09/24/2013] [Indexed: 11/09/2022]
Abstract
PURPOSE Head motion continues to be a major source of artifacts and data quality degradation in MRI. The goal of this work was to develop and demonstrate a novel technique for prospective, 6 degrees of freedom (6DOF) rigid body motion estimation and real-time motion correction using inductively coupled wireless nuclear magnetic resonance (NMR) probe markers. METHODS Three wireless probes that are inductively coupled with the scanner's RF setup serve as fiducials on the subject's head. A 12-ms linear navigator module is interleaved with the imaging sequence for head position estimation, and scan geometry is updated in real time for motion compensation. Flip angle amplification in the markers allows the use of extremely small navigator flip angles (∼1°). A novel algorithm is presented to identify marker positions in the absence of marker specific receive channels. Motion correction is demonstrated in high resolution 2D and 3D gradient recalled echo experiments in a phantom and humans. RESULTS Significant improvement of image quality is demonstrated in phantoms and human volunteers under different motion conditions. CONCLUSION A novel real-time 6DOF head motion correction technique based on wireless NMR probes is demonstrated in high resolution imaging at 7 Tesla.
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Affiliation(s)
- Saikat Sengupta
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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