We propose to prototype the first CT-MRI scanner for radiation therapy and basic research, demonstrate its transformative biomedical potential, and initiate a paradigm shift in multimodality imaging. Our design consists of a double donut-shaped pair of permanent magnets to form a regionally uniform ~0.5T magnetic field and leave room for a stationary 9-source interior CT gantry at 3 tube voltages (triple-energy CT). Image reconstruction will be in a compressive sensing framework. Please discuss with Dr. Ge Wang (ge-wang@ieee.org) if you are interested in collaborative opportunities.
Objectives Studies that assess magnetic resonance imaging (MRI) induced radiofrequency (RF) heating of the tissue in the presence of an active electronic implant are mostly performed in horizontal, closed-bore scanners. Vertical, open-bore MRI systems have a 90° rotated magnet and generate a fundamentally different RF field distribution in the body, yet little is known about the RF heating of deep brain stimulation (DBS) systems in this class of scanners. Here, we investigated whether RF heating of DBS devices was significantly different in a vertical, open-bore MRI scanner compared to a horiz…
Birth of the Coil: another Milestone towards a fully reproducible low-field MRI scanner for head-imaging
Istituto Nazionale di Ricerca Metrologica (INRiM)（意大利国家计量研究所）；Institute of Biomedical Imaging, Graz University of Technology（格拉茨工业大学生物医学成像研究所）；Physikalisch-Technische Bundesanstalt (PTB) Braunschweig and Berlin（德国联邦物理技术研究院）；Universidad Comunera（科穆内拉大学）；University of Alberta（阿尔伯塔大学）；Cross Cancer Institute（交叉癌症研究所）
Objective: Accurate estimation of SAR is critical to safeguarding vulnerable patients who require an MRI procedure. The increased static field strength and RF duty cycle capabilities in modern MRI scanners mean that systems can easily exceed safe SAR levels for patients. Advisory protocols routinely used to establish quality assurance protocols are not required to advise on the testing of MRI SAR levels and is not routinely measured in annual medical physics quality assurance checks. This study aims to develop a head phantom and protocol that can independently verify global SAR for MRI clinica…
Multi-modality imaging hardware can be integrated in a single gantry to collect diverse datasets for complementary information and spatiotemporal correlation, with excellent examples including PET-CT and PET-MRI. However, there is no CT-MRI prototype up to today due to technical challenges and associated cost-benefit considerations. Thanks to the rapid development of medical imaging, it becomes feasible now to integrate cost-effective CT and MRI imagers together for portability, popularity, and point of care. In this paper, we present the top-level design of the first portable CT-MRI system an…
Subject grounding to reduce electromagnetic interference for MRI scanners operating in unshielded environments
Leiden University Medical Center（莱顿大学医学中心）；Instituto de Instrumentación para Imagen Molecular (I3M), Centro Mixto CSIC-Universitat Politècnica de València（分子影像仪器研究所（I3M），CSIC-瓦伦西亚理工大学联合中心）
Magnetic resonance imaging (MRI) is the cornerstone technique for diagnostic medicine, biology, and neuroscience. This imaging method is highly innovative, noninvasive and its impact continues to grow. It can be used for measuring changes in the brain after enhanced neural activity, detecting early cancerous cells in tissue, as well as for imaging nanoscale biological structures, and controlling fluid dynamics, and it can be beneficial for cardiovascular imaging. The MRI performance is characterized by a signal-to-noise ratio, however the spatial resolution and image contrast depend strongly o…
Standard coils can cause inhomogeneities due to the standing wave patterns at ultra high field MRI. This B1 inhomogeneity can be overcome using the travelling-wave MRI (twMRI) approach. The ma- jority of twMRI research has been done with clinical MRI scanners at 7T or above. More recently, this concept has been also used with animal MRI systems, using circular-cross section waveguides and dielectric materials for both type of scanners. We have demonstrated that twMRI can be used at 3 T with clinical systems and a parallel-plate waveguide. Here, we investigated the use of a parallel- plate wave…
A Portable Brain MRI Scanner for Underserved Settings and Point-Of-Care Imaging
Athinoula A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital（阿西努拉·A·马丁诺斯生物医学成像中心放射科麻省总医院）；Harvard Medical School（哈佛医学院）；Dept. of Electrical Engineering, Massachusetts Institute of Technology（麻省理工学院电气工程系）；Dept. of Physics, Harvard University（哈佛大学物理系）；Dept. of Radiology, Massachusetts General Hospital（麻省总医院放射科）；Harvard-MIT Division of Health Sciences and Technology（哈佛-麻省理工健康科学与技术学部）
In-vivo imaging with a low-cost MRI scanner and cloud data processing in low-resource settings
MRILab, Institute for Molecular Imaging and Instrumentation (i3M), Consejo Superior de Investigaciones Científicas (CSIC) & Universitat Politècnica de València (UPV)（分子成像与仪器研究所 (i3M)，西班牙高等科学研究理事会 (CSIC) 与巴伦西亚理工大学 (UPV)）；Mbarara University of Science and Technology (MUST)（姆巴拉拉科技大学 (MUST)）；McGill University（麦吉尔大学）；Leiden University Medical Center (LUMC)（莱顿大学医学中心 (LUMC)）；Microsoft Research, Health Futures（微软研究院，健康未来部门）；Facultad de Ciencias Aplicadas, Universidad Comunera（应用科学学院，科穆内拉大学）；Yale University（耶鲁大学）
Background: Prostate cancer is one of the most common forms of cancer found in males making early diagnosis important. Magnetic resonance imaging (MRI) has been useful in visualizing and localizing tumor candidates and with the use of endorectal coils (ERC), the signal-to-noise ratio (SNR) can be improved. The coils introduce intensity inhomogeneities and the surface coil intensity correction built into MRI scanners is used to reduce these inhomogeneities. However, the correction typically performed at the MRI scanner level leads to noise amplification and noise level variations. Methods: In t…
An Exploration of Parallel Imaging System for Very-low Field (50mT) MRI Scanner
National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences（中国科学院精密测量科学与技术创新研究院武汉物理与数学研究所磁共振国家中心、磁共振与原子分子物理国家重点实验室）；The school of Electrical Engineering, Chongqing University（重庆大学电气工程学院）；A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital（麻省总医院放射科A.A.马丁诺斯生物医学成像中心）；Harvard Medical School（哈佛医学院）；Shenzhen Academy of Aerospace Technology（深圳航天科技创新研究院）；The school of Life Science, Northwestern Polytechnical University（西北大学生命科学学院）；Harbin Institute of Technology（哈尔滨工业大学）
Background: Parallel transmit (pTx) has introduced many benefits to MRI with regard to decreased specific absorption rates and improved transmit field homogeneity, of particular importance in applications at higher magnetic field strengths. PTx has also been proposed as a solution to mitigating dangerous RF induced heating of elongated conductive devices such as those used in cardiac interventions. In this work we present a system that can augment a conventional scanner with pTx, in particular for use in interventional MRI for guidewire safety. Methods: The pTx system was designed to work in-l…
Towards Sustainable Magnetic Resonance Imaging: Insights from long-term, high-resolution energy recordings across an entire scanner fleet
Medical Image and Data Analysis (MIDAS.lab), Tübingen University Hospital（蒂宾根大学医院医学影像与数据分析（MIDAS实验室））；Department of Diagnostic and Interventional Radiology, Tübingen University Hospital（蒂宾根大学医院诊断与介入放射科）；Faculty of Computer Science, Eberhard Karls University of Tübingen（埃伯哈德·卡尔斯·蒂宾根大学计算机科学学院）
Combining the unmatched soft-tissue imaging capabilities of magnetic resonance imaging (MRI) with high precision robotics has the potential to improve the accuracy, precision, and safety of a wide range of image-guided medical procedures. However, the goal of highly functional MRI-compatible robotic systems has not yet been realized because conventional electromagnetic servomotors used by medical robots can become dangerous projectiles near the strong magnetic field of an MRI scanner. Here we report a novel electromagnetic servomotor design that is constructed from non-magnetic components and …
Qualitative and quantitative hard-tissue MRI with portable Halbach scanners
MRILab, Institute for Molecular Imaging and Instrumentation (i3M), Spanish National Research Council (CSIC) and Universitat Politècnica de València (UPV)（分子成像与仪器研究所 (i3M)，西班牙国家研究理事会 (CSIC) 和瓦伦西亚理工大学 (UPV)）；Full Body Insight S.L.；PhysioMRI Tech S.L.
MRI offers outstanding soft tissue contrast that may reduce uncertainties in target and organ-at-risk delineation and enable online adaptive image-guided treatment. Spatial distortions resulting from non-linearities in the gradient fields and non-uniformity in the main magnetic field must be accounted for across the imaging field-of-view to prevent systematic errors during treatment delivery. This work presents a modular phantom and software application to characterize geometric distortion (GD) within the large field-of-view MRI images required for radiation therapy simulation. The modular pha…
Magnetic Resonance Imaging (MRI) of hard biological tissues is challenging due to the fleeting lifetime and low strength of their response to resonant stimuli, especially at low magnetic fields. Consequently, the impact of MRI on some medical applications, such as dentistry, continues to be limited. Here, we present three-dimensional reconstructions of ex-vivo human teeth, as well as a rabbit head and part of a cow femur, all obtained at a field strength of only 260 mT. These images are the first featuring soft and hard tissues simultaneously at sub-Tesla fields, and they have been acquired in…
A Review of Electromagnetic Elimination Methods for low-field portable MRI scanner
Harvard Medical School（哈佛医学院）；University of Michigan（密歇根大学）；Harvard University（哈佛大学）；New York University（纽约大学）；Columbia University（哥伦比亚大学）；Guangxi University（广西大学）
Image Sciences Institute, University Medical Center Utrecht（乌得勒支大学医学中心影像科学研究所）
Diffusion magnetic resonance imaging is a noninvasive imaging technique that can indirectly infer the microstructure of tissues and provide metrics which are subject to normal variability across subjects. Potentially abnormal values or features may yield essential information to support analysis of controls and patients cohorts, but subtle confounds affecting diffusion MRI, such as those due to difference in scanning protocols or hardware, can lead to systematic errors which could be mistaken for purely biologically driven variations amongst subjects. In this work, we propose a new harmonizati…
Real-time, inline quantitative MRI enabled by scanner-integrated machine learning: a proof of principle with NODDI
Hawkes Institute, Department of Computer Science, UCL（伦敦大学学院霍克斯研究所计算机科学系）；NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, UCL（伦敦大学学院脑科学学院神经炎症系女王广场多发性硬化中心核磁共振研究单元）；Research and Collaborations GBI, Siemens Healthcare Ltd（西门子医疗有限公司研究与协作GBI部门）；Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust（伦敦大学学院医院NHS基金会信托国家神经病学和神经外科医院Lysholm神经放射科）；Neuroradiological Academic Unit, Dept of Translational Neuroscience and Stroke, UCL Queen Square Institute of Neurology, UCL（伦敦大学学院女王广场神经学研究所转化神经科学与卒中系神经放射学学术单元）；Centre for Cardiovascular Imaging, Institute of Cardiovascular Science, UCL（伦敦大学学院心血管科学研究所心血管成像中心）；Department of Brain & Behavioural Sciences, University of Pavia（帕维亚大学脑与行为科学系）；Digital Neuroscience Centre, IRCCS Mondino Foundation（IRCCS蒙迪诺基金会数字神经科学中心）
After being hyperpolarized using the technique of Metastability Exchange Optical Pumping (MEOP), 3He can be used as a contrast agent for lung magnetic resonance imaging (MRI). MEOP is usually performed at low magnetic field (~ 1 mT) and low pressure (~ 1 mbar), which results in a low magnetization production rate. A delicate polarization-preserving step of compression is also required. It was demonstrated in sealed cells that high nuclear polarization values can be obtained at higher pressures with MEOP, if performed at high magnetic field (non-standard conditions). In this work the feasibilit…
High-spatial resolution, high-quality white matter tractography using DTI with dynamic slice-by-slice B0 shimming in a head-only high-gradient performance 3T MRI scanner
Quantitative mapping from conventional MRI using self-supervised physics-guided deep learning: applications to a large-scale, clinically heterogeneous dataset
University College London（伦敦大学学院）；University of Ibadan（伊巴丹大学）；Great Ormond Street Hospital for Children（大奥蒙德街儿童医院）；UCL Great Ormond Street Institute of Child Health（伦敦大学学院大奥蒙德街儿童健康研究所）；King’s College London（伦敦国王学院）；Microsoft Research Cambridge（微软剑桥研究院）；Department of Radiology, College of Medicine, University of Ibadan, Nigeria（伊巴丹大学医学院放射科）；Department of Paediatrics, College of Medicine, University of Ibadan, Nigeria（伊巴丹大学医学院儿科）；Centre for Medical Image Computing and Department of Computer Science, University College London, UK（伦敦大学学院医学影像计算中心和计算机科学系）；Department of Biomedical Engineering, King’s College London, UK（伦敦国王学院生物医学工程系）；Machine Intelligence and Perception Group, Microsoft Research Cambridge, UK（微软剑桥研究院机器智能与感知组）
1.5T or 3T scanners are the current standard for clinical MRI, but low-field (<1T) scanners are still common in many lower- and middle-income countries for reasons of cost and robustness to power failures. Compared to modern high-field scanners, low-field scanners provide images with lower signal-to-noise ratio at equivalent resolution, leaving practitioners to compensate by using large slice thickness and incomplete spatial coverage. Furthermore, the contrast between different types of brain tissue may be substantially reduced even at equal signal-to-noise ratio, which limits diagnostic value…
Karolinska Institutet（卡罗林斯卡医学院）；Karolinska University Hospital（卡罗林斯卡大学医院）；Stavanger University Hospital（斯塔万格大学医院）；University of Stavanger（斯塔万格大学）；University of Brescia（布雷西亚大学）；Masaryk University（马萨里克大学）；St. Anne’s Hospital（圣安妮医院）；University G d’Annunzio of Chieti-Pescara（基耶蒂-佩斯卡拉加布里埃莱·邓南遮大学）
Deep learning (DL) methods have in recent years yielded impressive results in medical imaging, with the potential to function as clinical aid to radiologists. However, DL models in medical imaging are often trained on public research cohorts with images acquired with a single scanner or with strict protocol harmonization, which is not representative of a clinical setting. The aim of this study was to investigate how well a DL model performs in unseen clinical data sets---collected with different scanners, protocols and disease populations---and whether more heterogeneous training data improves…
The coaxial cables commonly used to connect RF coil arrays with the control console of an MRI scanner are susceptible to electromagnetic coupling. As the number of RF channel increases, such coupling could result in severe heating and pose a safety concern. Non-conductive transmission solutions based on fiber-optic cables are considered to be one of the alternatives, but are limited by the high dynamic range ($>80$~dB) of typical MRI signals. A new digital fiber-optic transmission system based on delta-sigma modulation (DSM) is developed to address this problem. A DSM-based optical link is pro…
