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Yongquan Ye¹, Zhongqi Zhang¹, and Jian Xu^1
1United Imaging, Houston, TX, United States

Keywords: Multi-Contrast, Body

A multi-parametric method with WFI imaging capacity, i.e. MULTIPLEX-WFI, was developed and demonstrated. Routine two-point Dixon WFI images are additionally achieved, and a fat-suppression mask is extracted for use on the MULTIPLEX images to improve the overall image quality for body imaging. The cost of adding the WFI capacity to the MULTIPLEX method was negligible. The MULTIPLEX-WFI method was tested on phantom and in vivo knee and pelvis scans, showing much improved imaging quality for body imaging. 

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Yan Wu¹, Zhitao Li¹, Marcus Alley¹, Zhifei Wen², Zheng Zhong¹, Fan Zhang³, John Pauly¹, and Shreyas Vasanawala^1
1Radiology, Stanford University, Stanford, CA, United States, ²Hoag Hospital, Newport Beach, CA, United States, ³Radiology, Stanford Children's Hospital, Stanford, CA, United States

Keywords: Fat, Fat, deep learning, dual-echo water-fat separation, flexible echo time

We designed a deep learning-based dual-echo water-fat separation method with capability to support flexible echo times. A densely connected hierarchical network was employed, where input included dual-echo images and echo times, and ground truth images were produced using the projected power method. The model was trained and tested using 78 contrast enhanced image sets acquired with optimal echo times, and further validated on 15 non-contrast enhanced image sets obtained with different imaging parameter values. The proposed water-fat separation method has demonstrated high accuracy when dual-echo images were acquired with optimal or non-optimal echo times.

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Juhyung Park¹, Chungseok Oh¹, Sooyeon Ji¹, Jonghyo Youn¹, and Jongho Lee^1
1Seoul National University, Seoul, Korea, Republic of

Keywords: Susceptibility, Susceptibility

A new denoising network, HiFNet, for complex valued multi-echo GRE image denoising, is proposed. This network shared network features hierarchically from the first echo image to the last echo image, utilizing the redundancy in multi-echo GRE images along the echo dimension. When tested with synthetic noise denoising and real-world denoising experiments, the proposed network shows better performance than a network with no featuring or feature sharing in reverse order, demonstrating the effectiveness of the proposed feature sharing.

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Chaoyue Wang^1,2, Aaron T. Hess¹, William T. Clarke¹, Stuart Clare¹, Diego Hernando³, Scott B. Reeder³, Karla L. Miller¹, and Benjamin C. Tendler^1
1Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University Of Oxford, Oxford, United Kingdom, ²SJTU-Ruijin-UIH Institute for Medical Imaging Technology, Shanghai, China, ³Departments of Radiology, University of Wisconsin, Madison, WI, United States

Keywords: Electromagnetic Tissue Properties, Electromagnetic Tissue Properties

Our results suggest that R2* maps in UK Biobank are confounded by the macroscopic field variation which leads to spurious associations driven by field variations due to the air/tissue interfaces. This effect can be modeled as a signal modulation which can be removed through a voxel-wise correction.

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Eugene Milshteyn¹, Harry Griffin², Yi Shuen Chang², Tim Sprenger^3,4, Stefan Skare^4,5, Christopher J. Maclellan², and Salil Soman^2
1GE Healthcare, Boston, MA, United States, ²Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, ³GE Healthcare, Stockholm, Sweden, ⁴Karolinska Institutet, Stockholm, Sweden, ⁵Karolinska University Hospital, Stockholm, Sweden

Keywords: Multi-Contrast, Brain

The focus of this study is to assess the diagnostic performance of NeuroMix, a single push-button, novel, fast multi-contrast MRI sequence, to that of routine brain scans that typically consist of multiple sequences. NeuroMix has the ability to provide several different contrasts in about 3.5 minutes with only one prescription and prescan. While the sequence has initially shown to be fast and motion-robust, more evaluation is needed across the various contrasts compared to gold standard, optimized sequences routinely used in the clinic. Here we present initial qualitative and quantitative comparisons between NeuroMix and routine scans across a variety of patients.

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Adrienne G. Siu¹, Boyan Ivanov¹, Alex K. Smith¹, Matthew D. Robson¹, and Roberto Salvati^1
1Perspectum, Oxford, United Kingdom

Keywords: Relaxometry, Phantoms, Temperature

Phantom vials of varying T2 were calibrated as a function of temperature, where the temperature was measured via multi-echo gradient echo imaging of ethylene glycol in a phantom vial. The temperature calibrations were used to adjust T2 to a reference temperature, achieving T2 deviations to within [-3.2, 2.0] ms [-3.1%, 2.9%] on Siemens 3T (16.7ºC – 25.1ºC) and [-3.5, 1.4] ms [-3.4%, 0.8%] on GE 1.5T (16.5ºC – 23.7ºC). This demonstrates that corrections for T2 due to temperature can be performed while measuring temperature from gradient-echo imaging of ethylene glycol.

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Qizeng Ruan¹, Zehe He¹, Zeping Liu², Yuhui Nie², Liping Liao¹, Qingchun Li¹, Mingxia Tan¹, Lanbin Huang¹, Guoxi Xie², YuanLi Wang¹, and Minglu Zhou^1
1The First People’s Hospital of Qinzhou, Qinzhou, China, ²Guangzhou Medical University, Guangzhou, China

Keywords: Relaxometry, Cardiovascular, T1 mapping

Carotid plaque is an important cause of stroke. The T1 value of the plaque could provide potential information for the diagnosis. In this work, we compared the performance of T1 mapping of BB-MP2RAGE and conventional MP2RAGE in carotid plaque. Experiments demonstrated BB-MP2RAGE could achieve more accurate measurement of T1 value for diagnosis of carotid plaque.

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Lauritz Klünder¹, Bastian Maus¹, Maria Belen Rivas Aiello², Thomas Kirse^3,4, Cristian Strassert^3,4, and Cornelius Faber^1
1Clinic of Radiology, University of Münster, Münster, Germany, ²Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Universidad Nacional de La Plata - CONICET, La Plata, Argentina, ³Institut für Anorganische und Analytische Chemie, University of Münster, Münster, Germany, ⁴CeNTech, CiMIC, SoN, University of Münster, Münster, Germany

Keywords: Relaxometry, Contrast Agent, Simulations

Physico-chemical properties of superparamagnetic iron oxide nanoparticles (IONP) strongly affect their impact on transverse relaxation and their efficiency as MR contrast agents. Monte Carlo simulations were developed to model relaxation in silico for two novel IONPs with distinct physico-chemical properties. The IONPs comprised an identical magnetite core but differed in preparation strategy, defining their coating and size. Simulations were compared to in vitro relaxometry measurements and reproduced experimentally measured relaxation times. Using lognormally distributed particle radii in the simulations was required to obtain correct R₂^* values. Together, simulations and measurements unveiled additional particle aggregation in the MR samples.

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Lixian Wang^1,2, Tomohisa Okada³, Takashi Hanakawa^1,3, Baogui Zhang^2,4, Huilou Liang², Jing An⁵, Rong Xue^2,4,6, and Fangrong Zong^2,7
1Department of Integrated Neuroanatomy and Neuroimaging, Kyoto University, Kyoto, Japan, ²Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, ³Human Brain Research Center, Kyoto University, Kyoto, Japan, ⁴University of Chinese Academy of Sciences, Beijing, China, ⁵Siemens Shenzhen Magnetic Resonance Ltd, Shenzhen, China, ⁶Beijing Institute for Brain Disorders, Beijing, China, ⁷School of Artificial Intelligence, Beijing University of Posts and Telecommunications, Beijing, China

Keywords: Multi-Contrast, Diffusion/other diffusion imaging techniques

Multidimensional MRI resolves the correlations between physical parameters and relaxation properties and has become an increasingly important protocol in biomedical engineering. It has sub-voxel resolution but most research still uses multi-voxel ROIs. In this study, we obtained the single voxel T₁-D Relaxation-Diffusion correlation spectra from in vivo human brain tissue boundaries. The significant variance in these spectra might help to identify tissue microstructure at the sub-voxel resolution. Our research disclosed the feasibility of applying multidimensional MRI techniques to detect and segment the human brain.

Jie Yang¹, Hao Feng¹, Meining Chen², Xu Yan², Jianqi Li³, Yinqiao Yi³, Haodong Zhong³, and Jianquan Zhong^1
1Department of Radiology, Zigong First People's Hospital, Zigong, China, ²MR Scientific Marketing, Siemens Healthineers, Shanghai, China, ³Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China

Keywords: Multi-Contrast, Multi-Contrast

The quantitative MRI mapping techniques showed great potential in evaluating intervertebral disc degeneration (IVD) and diagnosing lower back pain. The repeatability of the quantitative methods is very important for clinical evaluation. A simultaneous multi-relaxation-time mapping (TXI) method was evaluated here, which can quantify the bone marrow fat fraction (BMFF), R2* and R1 value by a single scan and fast speed. The quantitative parameters of TXI showed high repeatability with high consistency and low CoVs, and could be applied in future clinical applications of IVD degeneration disease.

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Milena Capiglioni¹, Federico Turco¹, Claus Kiefer¹, and Roland Wiest^1
1Support Center for Advanced Neuroimaging (SCAN), University of Bern, Bern, Switzerland

Keywords: Electromagnetic Tissue Properties, Simulations, Spin-lock, Neuronal Current Imaging

Different SL techniques have been proposed to generate images based with a contrast based on neuronal activity. We analyzed the contrast of different SL techniques for the detection of oscillatory magnetic fields and their dependence with the duration of the SL and the initial phase of the target field. 

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Maira Tariq^1,2, Alison Macdonald², Mathew R Orton^1,2, Michael J Dubec³, David J Collins^1,2, Jessica M Winfield^1,2, and James P B O’Connor^1,3,4
1Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom, ²MRI Unit, The Royal Marsden NHS Foundation Trust, London, United Kingdom, ³Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom, ⁴Radiology, The Christie NHS Foundation Trust, Manchester, United Kingdom

Keywords: Relaxometry, Quantitative Imaging, Oxygen-Enhanced MRI

Hypoxia is an important prognostic factor for head and neck cancers (HNC). Oxygen-Enhanced MRI (OE-MRI) can map hypoxia, by quantifying change in longitudinal relaxation time, T₁, but the technique suffers from low signal-to-noise ratio (SNR), which reduces the sensitivity of hypoxia detection. We optimised standard T₁ mapping methods on a 1.5T scanner, to select an accurate, precise, and high SNR sequence, derived in a phantom and in healthy volunteers. 3D Variable Flip Angle spoiled gradient-echo acquisition with view-sharing, flip angles 2^o and 8-10^o and with B₁ correction applied provided suitable protocol for clinical application.

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Colin Vanden Bulcke^1,2, Nicolas Delinte², and Benoît Macq^2
1Institute of Neurosciences, Université Catholique de Louvain, Brussels, Belgium, ²Institute for Information and Communication Technologies, Electronics and Applied Mathematics, Université Catholique de Louvain, Louvain-la-Neuve, Belgium

Keywords: Multi-Contrast, Multiple Sclerosis, Paramagnetic Rim Lesions

Chronic active multiple sclerosis (MS) lesions are visible on susceptibility-based MRI as paramagnetic rim lesions (PRL); these lesions are characterized by severe tissue damage and strongly correlate with disease severity. PRL assessment is usually performed manually on unwrapped-filtered phase images. However, PRL assessment is associated with high intra/inter-rater variability due to the poor visibility of PRL and to the lack of standardized imaging protocols/guidelines for their detection. Here, we propose a new synthetic contrast called FLAIR³Phase to augment PRL assessment workflow and to reduce rater variability.

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Yicun Wang¹, Peter van Gelderen¹, Jacco A de Zwart¹, and Jeff H Duyn^1
1AMRI, LFMI, NINDS, NIH, Bethesda, MD, United States

Keywords: Relaxometry, Brain

Gradient Echo Sampling of Spin Echo signal was used to obtain R₂ maps in nine adults at 3 T and 7 T. These were analyzed using anatomically defined ROIs, across most of the brain. Comparison between the two field strengths shows in most brain regions the R₂ increases by about a factor of 1.62, with the notable exception of regions high in iron. Linear fits of R₂ versus estimated iron concentration yielded 50.6 and 132 1/s/(mg/g) for 3 T and 7 T respectively, in line with prior reports at lower fields for the field dependence of iron related relaxation.

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Yicun Wang¹, Peter van Gelderen¹, Jacco de Zwart¹, and Jeff H. Duyn^1
1AMRI, LFMI, NINDS, NIH, Bethesda, MD, United States

Keywords: Relaxometry, Relaxometry, T2 mapping; Iron

Gradient Echo Sampling of Spin Echo signal was used to obtain whole-brain R₂ maps from 8 young and 1 senior healthy volunteers at 7T. Cortical surface reconstruction showed increased R₂ in areas of high iron content as known from histology. Furthermore, high R₂ in sensory-motor and visual cortices was accompanied by low R₂ in underlying white matter. Highest R₂ in subcortical white matter was found in frontal and temporal lobes. The low sensitivity of R₂ to fiber orientation and venous vasculature may render it more suitable than R₂^* and $$$\chi$$$ for iron quantification, especially near the brain surface.

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Kevin D Harkins^1,2,3, Jason Ostenson^1,2, Fatemeh Adelnia^1,2, Feng Wang^1,2, Zhongliang Zu^1,2, and John C Gore^1,2,3
1Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, ²Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, ³Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

Keywords: Relaxometry, Simulations

R_1σ dispersion imaging can be used to uncover specific relaxation mechanisms in soft tissues, but is sensitive to B₀ and B₁ inhomogeneity. Several varieties of R_1σ preparation pulses have been developed to reduce sensitivity to B₀ and B₁, typically by introducing a spin echo or double spin echo as part of the preparation pulse. This simulation study shows that such pulses can actually reduce the sensitivity to R_1σ dispersion. 

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Hannah J. S. Ehler¹, Sharon Clarke^2,3, Geoff Williams^4,5, and James Rioux^1,2,3
1Department of Physics & Atmpspheric Science, Dalhousie University, Halifax, NS, Canada, ²Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada, ³BIOTIC, Nova Scotia Health, Halifax, NS, Canada, ⁴Department of Digestive Care & Endoscopy, Dalhousie University, Halifax, NS, Canada, ⁵Nova Scotia Health, Halifax, NS, Canada

Keywords: Relaxometry, Pancreas, T1rho

T1ρ quantification in the pancreas is largely unexplored due to the difficulty of compensating for breathing motion. In this study we demonstrate a free-breathing T1ρ technique for use in the abdomen which is able to quantify T1ρ in the pancreas without respiratory gating, through the use of golden-angle radial sampling. The technique was validated in phantoms and tested in three healthy volunteers. T1ρ values in the liver and spleen agreed with recent literature, while differences in T1ρ values in the pancreas may be related to the use of free breathing instead of respiratory gating.

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Vivian S. Nguyen^1,2, Sudarshan Ragunathan³, Timothy J. Carroll⁴, Adil Javed⁵, Marcella K. Vaicik¹, John G. Georgiadis¹, and Keigo Kawaji^1,2
1Biomedical Engineering, Illinois Institute of Technology, Chicago, IL, United States, ²Medicine - Cardiology, University of Chicago Medical Center, Chicago, IL, United States, ³Hyperfine Inc., Guilford, CT, United States, ⁴Radiology, University of Chicago Medical Center, Chicago, IL, United States, ⁵Neurology, University of Chicago Medical Center, Chicago, IL, United States

Keywords: Relaxometry, Low-Field MRI

T1 maps provide quantitative relaxometric measures of tissue responses that may carry correlative indices of specific disease indications. On the recently commercialized 64mT system (Hyperfine Inc.), little has been reported regarding both clinical T1 relaxometric normal values in presence of Gadolinium-based contrast and relevant acquisition schemes with Gd contrast enhancement. In this study, we examine an array of Gadolinium-doped vials that represent 10-5000 fold dilution in the vasculature using an Inversion-Recovery FSE acquisition to gain key insights on: a) anticipated normal values in presence of Gd, b) conventional fitting algorithm performance, and c) potential inferences on inversion timing selection.