| 15:45 | 1085.
 | Non-invasive high-resolution in vivo pH mapping in brain tumors by 31P‑informed deepCEST MRI Jan-Rüdiger Schüre1, Junaid Rajput1, Eike Steidl2, Manoj Shrestha3, Ralf Deichmann3, Elke Hattingen2, Moritz Fabian1, Andreas Maier4, Armin Nagel5, and Moritz Zaiss1,4,6
1Institute of Neuroradiology, Erlangen, Germany, 2Institute of Neuroradiology, Frankfurt am Main, Germany, 3Brain Imaging Center, Frankfurt am Main, Germany, 4Department Artificial Intelligence in Biomedical Engineering, Erlangen, Germany, 5Institute of Radiology, Erlangen, Germany, 6Max-Planck Institute for Biological Cybernetics, Tübingen, Germany Keywords: CEST / APT / NOE, CEST & MT, Cancer, pH, CEST, 31P, Neuronal Network Motivation: The pH value is an important biomarker for many diseases. MRI-based 3D pH mapping for clinical routine would be an enormous benefit for diagnostics. Goal(s): Prediction of intracellular 31P-pHi maps from 1H APTw-CEST MRI data using a voxel-wise neural network, aiming to improve brain tumor imaging. Approach: Fifteen glioblastoma patients underwent 3T MRI with both APTw-CEST and 31P-MRS. A neural network trained on 11 patients data to correlate APTw-CEST features with 31P-derived pHi values, tested on 4 additional patients. Results: The neural network's pHi predictions closely matched 31P-pHi maps, showing potential for high-resolution, non-invasive pHi mapping in brain tumors. Impact: High resolution pH
imaging for better diagnosis of diseases (inflammation, stroke, tumor) and
therapy monitoring in clinical routine. |
| 15:45 | 1086.
 | Non-invasive mapping of brown adipose tissue activity with MRI Zimeng Cai1,2, Qiaoling Zhong3, Yanqiu Feng4,5,6, Zhigang Wu7, Changhong Liang1,2, Chong Wee Liew8, Lawrence Kazak9,10, Aaron M. Cypess11, Zaiyi Liu1,2, and Kejia Cai12,13
1Department of Radiology, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China, 2Guangdong Provincial Key Laboratory of Artificial Intelligence in Medical Image Analysis and Application, Guangzhou, China, 3Department of Radiology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangdong Provincial Clinical Research Center for Child Health, Guangzhou, China, 4School of Biomedical Engineering, Southern Medical University, Guangzhou, China, 5Guangdong Provincial Key Laboratory of Medical Image Processing & Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology, Southern Medical University, Guangzhou, China, 6Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence & Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China, 7Philips Healthcare (Shenzhen) Ltd, Shenzhen, China, 8Physiology and Biophysics Department, University of Illinois at Chicago, Chicago, IL, United States, 9Rosalind & Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada, 10Department of Biochemistry, McGill University, Montreal, QC, Canada, 11Diabetes, Endocrinology, and Obesity Branch, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Bethesda, MD, United States, 12Radiology Department, University of Illinois at Chicago, Chicago, IL, United States, 13Biomedical Engineering Department, University of llinois at Chicago, Chicago, IL, United States Keywords: CEST / APT / NOE, Metabolism Motivation: Through non-shivering thermogenesis, brown adipose tissue (BAT) plays a critical and beneficial role in obesity and metabolic diseases. Goal(s): In this study, we developed non-invasive creatine CEST (CrCEST) MRI of adipose tissues for mapping BAT activity in both rodents and humans given to creatine’s important role in bioenergetics. Approach: We observed by CrCEST MRI that the changes in BAT activity in rats and human after drug administration and/or cold exposure were in good agreement with traditional 18F-FDG PET/CT imaging. Results: The results of this study demonstrated CrCEST MRI as an endogenous, non-invasive, and radiation-free method for in vivo mapping of BAT activity. Impact: In this study, endogenous CrCEST MRI of
adipose tissues was developed and found to serve as an imaging biomarker for BAT
activity, the diagnosis of metabolic diseases, and the evaluation of new
therapeutic strategies in a longitudinal and non-invasive means. |
| 15:45 | 1087.
 | Accelerated CEST Imaging with Deep Learning Priors and Synthetic Brain Tumor Datasets Yuyan Wang1, Jianping Xu1, Zhechuan Dai1, Yi-Cheng Hsu2, and Yi Zhang1
1Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China, 2MR Collaboration, Siemens Healthcare Ltd., Shanghai, China Keywords: CEST / APT / NOE, Machine Learning/Artificial Intelligence, Synthetic Datasets Motivation: The clinical application of CEST MRI is constrained by its relatively long scan time. Goal(s): We aim to develop a deep learning reconstruction method for accelerating CEST imaging in the absence of true experimental data. Approach: Here, we propose a model-based deep learning framework, in conjunction with the Channel-wise Attention mechanism and Total variation regularization, dubbed as MoDL-CAT. Moreover, we propose a new workflow to synthesize CEST data from the BraTS and fastMRI repositories. Results: We demonstrate that the BraTS-CEST dataset can improve the performance of all deep learning networks tested, and the MoDL-CAT method achieves superior reconstruction quality to the state-of-the-art methods. Impact: The proposed deep learning framework with
channel-wise attention may offer a better prior for reconstruction. And our
novel workflow to synthesize high-quality brain tumor CEST datasets might help
researchers with limited data to explore various methods for accelerating CEST
imaging. |
| 15:45 | 1088.
 | Rapid and simplified post-processing for B0 and B1 mapping with WASABI-RADISH in the application of CEST at 7T Mara Quach1,2, Myrte Strik2,3,4, Rebecca Glarin2, Bradford A Moffat2, David K Wright5, and Leigh A Johnston1,2
1Department of Biomedical Engineering, University of Melbourne, Parkville, Australia, 2Melbourne Brain Centre Imaging Unit, University of Melbourne, Parkville, Australia, 3Spinoza Centre for Neuroimaging, Royal Netherlands Academy of Sciences, Amsterdam, Netherlands, 4Department of Computational Cognitive Neuroscience & Neuroimaging, Netherlands Institute for Neuroscience, Royal Netherlands Acadamy of Arts and Sciences, Amsterdam, Netherlands, 5Central Clinical School, Department of Neuroscience, Monash University, Melbourne, Australia Keywords: CEST / APT / NOE, CEST & MT, B1, B0, WASABI, data processing, UHF, 7T, tools Motivation: WASABI provides high fidelity B0 and B1 maps necessary for CEST correction yet suffers from prolonged post-processing incompatible with clinical use. Goal(s): Our goal was to design an optimisation-free method to expedite map estimations. Approach: A direct relationship was derived between B0 and B1 and information in WASABI Z-spectra. Results: The proposed approach accelerated post-processing by a factor of 80, with improved estimation in brain regions that are noisy and/or have unpredictable initial magnetisation. Impact: Improvement in speed and accuracy provided by RADISH has the ability to make WASABI, and quantitative CEST at ultra-high-field in general, more reliable and clinically feasible. |
| 15:45 | 1089.
 | Fast, motion-robust CEST imaging with inherent B0 correction using rosette trajectories Sultan Zaman Mahmud1, Munendra Singh1, Peter van Zijl1, and Hye-Young Heo1
1Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States Keywords: CEST / APT / NOE, CEST & MT Motivation: CEST-MRI typically requires a long scan time and an additional B0 map scan for inhomogeneity correction. Goal(s): To implement a rosette readout for fast CEST imaging with improved robustness to bulk-motion and inherent correction of B0 inhomogeneity. Approach: Rosette trajectories which sample more densely near the k-space center provided faster and more motion-robust CEST imaging than Cartesian trajectories. B0 inhomogeneities were estimated using the phase difference between two images from two halves of the rosette lobe and corrected subsequently. Results: Rosette trajectories significantly reduced the CEST imaging time. No extra scans were needed for B0 correction due to the inherent B0 mapping capability. Impact: Fast,
motion-robust, and inherent B0-corrected CEST imaging with rosette trajectories
can help improve patient comfort and compliance. The work is expected to
significantly accelerate the translation of CEST-MRI into a robust clinically
viable approach. |
| 15:45 | 1090.
 | Orientation Dependence of Magnetization Transfer and “Inhomogeneous Magnetization Transfer” in Spinal Cord Niklas Wallstein1, André Pampel1, Carsten Jäger2,3, Roland Müller1, Jens Stieler3, Sven Martin3, Markus Morawski2,3, and Harald E. Möller1,4
1NMR Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 2Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 3Center of Neuropathology and Brain Research, Medical Faculty, University of Leipzig, Paul Flechsig Institute, Leipzig, Germany, 4Felix Bloch Institute for Solid State Physics, Leipzig University, Leipzig, Germany Keywords: Magnetization Transfer, Magnetization transfer, Inhomogeneous Magnetization Transfer, Orientation Dependence, Spinal Cord Motivation: Magnetization transfer (MT) and inhomogeneous MT (ihMT) are assumed to report on myelin content. Recently, anisotropy of MT and ihMT have been demonstrated in model systems and in white matter. Goal(s): Our goal was to quantify orientation effects in (ih)MT, as they closely relate to the microstructure and serve to confirm assumptions about the relaxation mechanism. Approach: Comprehensive (ih)MT investigations were performed in fixed spinal cord with variation of the fiber-to-field angle (θFB). Results: Unambiguous orientation dependence was observed for (ih)MT. The variation depends strongly on the offset frequency, which was quantitatively predicted in simulations of the BSBM with a realistic fiber model. Impact: This study investigates the orientation dependency of magnetization transfer and related model parameters. Some subtle orientation effects are observed for the first time and are quantitatively explained by using a reasonable model for the RF saturation lineshape. |
| 15:45 | 1091.
 | Large-shift, Rapid Exchange Endogenous CEST Contrast for Reporter Gene Product Design David Edward Korenchan1, Nicolas Scalzitti2, Michael T McMahon3, Assaf Gilad2, and Christian T Farrar1
1Radiology, Athinoula A. Martinos Center, Massachusetts General Hospital, Charlestown, MA, United States, 2Michigan State University, East Lansing, MI, United States, 3Radiology and Radiological Sciences, F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States Keywords: CEST / APT / NOE, CEST & MT Motivation: Endogenous CEST contrast from reporter gene products would benefit from exchangeable protons resonating above 3.5 ppm and exchanging rapidly. Goal(s): We sought to characterize high-shift CEST contrast in tryptophan-enriched peptide sequences to design a highly specific and selective reporter gene protein product. Approach: We performed CEST z-spectroscopy and QUESP analysis on several tryptophan-containing peptide sequences with variations on a WDWEQ motif. Results: We identified a CEST z-peak at 5.5 ppm exchanging at 250-350 s-1. Surprisingly, we also discovered a new fast-exchanging (ksw ~ 1800 s-1) CEST resonance at 4.4 ppm in one peptide. Both improve our ability to generate unique CEST contrast. Impact: Developing selective and specific MRI-detectable CEST contrast will greatly benefit noninvasive assessment of viral and cell based therapies. Our work in high-shift CEST contrast shows great potential to improve our ability to reliably monitor these therapies. |
| 15:45 | 1092.
 | Highly Accelerated CEST Imaging with Stack-of-stars Acquisition using Unsupervised Implicit Neural Representation Networks Bei Liu1, Huajun She1, and Yiping Du1
1Shanghai Jiao Tong University, Shanghai, China Keywords: CEST / APT / NOE, CEST & MT Motivation: Reduction of scan time in CEST imaging is clinically meaningful. Goal(s): Our goal is to develop an undersampled reconstruction algorithm to help vastly reduce the acquisition time. Approach: A novel unsupervised deep-learning based algorithm is proposed to accelerate steady-state pulsed CEST imaging with golden-angle stack-of-stars trajectory using mixed-feature hash encoding implicit neural representation. Additionally, Imaging quality is further improved using the explicit prior knowledge of weighted joint sparsity in subtle structural features of CEST image domain. The low rankness and sparsity in the Z‐spectra domain are used to reduce acquisition time. Results: It is possible to achieve a 30-fold acceleration for CEST imaging. Impact: An unsupervised deep-learning algorithm
is proposed to accelerate steady-state pulsed CEST imaging with golden-angle stack-of-stars
trajectory using mixed-feature hash encoding implicit neural representation and
weighted joint sparsity. It can vastly reduce the acquisition time and
has potential for clinical applications. |
| 15:45 | 1093.
 | Magnetic Resonance Fingerprinting of the Chemical Exchange Relayed Nuclear Overhauser Effect In Vivo (rNOE-MRF) Inbal Power1, Michal Rivlin2, Gil Navon2, and Or Perlman1,3
1Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel, 2School of Chemistry, Tel Aviv University, Tel Aviv, Israel, 3Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel Keywords: CEST / APT / NOE, CEST & MT Motivation: Despite its demonstrated ability to provide biological insights into various pathologies, relayed nuclear Overhauser effect (rNOE) imaging is lengthy and biased by water T1 and semisolid MT contrast.
Goal(s): To develop a rapid rNOE quantification MR-Fingerprinting (MRF) method and validate its performance in-vivo.
Approach: An rNOE-MRF acquisition protocol was designed and employed at 7T for imaging three in-vitro tissue types and wild-type mice (n=7). Quantitative glycogen, rNOE, and semisolid MT maps were simultaneously reconstructed.
Results: In-vitro rNOE exchange parameter maps were highly correlated with ground truth (r>0.99, p<0.01, NRMSE<7%). The rNOE and MT quantitative trends in mice were in agreement with previous literature.
Impact: A
quantitative molecular MR-Fingerprinting method was developed,
allowing for the simultaneous extraction of rNOE and semisolid MT
proton-exchange
parameter maps. These in-vivo, bias-dismantled maps are expected to
aid in the diagnosis and
characterization of
cancer, stroke, and spinal cord injury. |
| 15:45 | 1094.
 | Frequency-selective inversion nulling ultra-short echo time (FINUTE) MRI for direct detection of lipids of the myelin bilayer Anshuman Swain1, Narayan Datt Soni2, Neil Wilson2, and Ravinder Reddy2
1Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States, 2Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States Keywords: CEST / APT / NOE, New Signal Preparation Schemes, Short T2, Lipids, Myelin Motivation: Recent studies have shown the effects of lipid dyshomeostasis and demyelination in the pathology of neurodegenerative diseases, especially early-onset Alzheimer’s disease. Consequently, imaging methods to monitor these changes are necessary. Goal(s): This study uses a novel sequence, termed FINUTE, to image short T2 lipids primarily associated with the myelin bilayer. Approach: Simulations and experiments on ex-vivo spinal cord specimens are performed for validation of methodology and applied in-vivo to assess changes in myelination in a mouse model of AD. Results: Results demonstrate FINUTE’s sensitivity to myelin lipids, with statistically significant white matter(corpus callosum) and visually-apparent gray matter(hippocampus) changes present in AD animals. Impact: FINUTE presents a non-invasive MR-imaging technique that is sensitive to lipids primarily in the myelin bilayer as well as in gray matter, thus providing a method for assessing myelination and lipid dyshomeostasis in neurodegenerative diseases such as AD. |
| 15:45 | 1095.
 | Optimization of sparse saturation transfer MR fingerprinting (ST-MRF) by ranking the importance of saturation transfer contrast features Munendra Singh1, Sultan Zaman Mahmud1, Peter van Zjil1, and Hye-Young Heo1
1Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, United States Keywords: CEST / APT / NOE, CEST & MT Motivation: Optimizing ST-MRF sequence design is critical to accelerate image acquisition and improve reconstruction accuracy. Goal(s): To develop a deep-learning framework that can optimize MRF acquisition for tissue parameter determination with a minimal number of scan parameter settings. Approach: An interpretable neural network was designed to optimize MRF sequences by ranking the importance of saturation contrast features and evaluated using numerical phantoms and in vivo experiments at 3T. Results: Importance-ranking network-based sequence optimization demonstrated its ability to improve the choice of scan parameter values for quantification of tissue parameters. Sequence optimization achieved 1.7-fold acquisition acceleration without compromising the fidelity of the tissue parameter quantification. Impact: Ranking the importance of saturation transfer contrast features facilitates choosing the best combination of sequence parameters for tissue quantification with fingerprinting (ST-MRF). An interpretable network based on importance ranking can significantly accelerate data acquisition for ST-MRF and conventional Z-spectral acquisition. |
| 15:45 | 1096.
 | High-Resolution Reduced FOV Renal Chemical Exchange Saturation Transfer MRI Using orthogonal RF pulses Qianqian Zhang1,2, Zelong Chen3, Zhigang Wu4, Kan Deng5, Quan Tao2,6, Wenyan Zhang1,2, Yizhe Zhang1,2, Yikai Xu3, and Yanqiu Feng1,2
1School of Biomedical Engineering, Southern Medical University, Guangzhou, China, 2Guangdong Provincial Key Laboratory of Medical Image Processing & Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology, Southern Medical University, Guangzhou, China, 3Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China, 4Philips Healthcare, Shenzhen, China, 5Philips Healthcare, Guangzhou, China, 6Department of Rehabilitation, Zhujiang Hospital, Southern Medical University, Guangzhou, China Keywords: CEST / APT / NOE, CEST & MT Motivation: Long scanning time and low resolution limit the chemical exchange saturation transfer (CEST) clinical translation. Goal(s): We aimed to develop a high-resolution renal reduced field of view CEST (rCEST) technique to reduce scanning time. Approach: The rFOV based on orthogonal RF pulses in combination with conventional CEST module was performed on a volunteer and compared this technique with full-size FOV CEST (fCEST). Results: Compared to fCEST, rCEST has shorter scanning time, higher image quality, and better saturation efficiency at the same image resolution. Impact: The rCEST technique may have potential for clinical applications requiring high resolution and metabolic renal CEST-MR image. |
| 15:45 | 1097.
 | Amide proton transfer weighted signal of multiple sclerosis lesions and normal appearing white matter Ibrahim Khormi1,2,3, Oun Al-iedani2,4, Stefano Casagranda5, Christos Papageorgakis5, Abdulaziz Alshehri1,2,6, Rodney Lea2, Patrick Liebig7, Saadallah Ramadan1,2, and Jeannette Lechner-Scott2,8,9
1School of Health Sciences, University of Newcastle, Callaghan, Australia, 2Hunter Medical Research Institute, New Lambton Heights, Australia, 3College of Applied Medical Sciences, University of Jeddah, Jeddah, Saudi Arabia, 4School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia, 5Department of R&D Advanced Applications, Olea Medical, La Ciotat, France, 6Department of Radiology, King Fahd Hospital of the University, Imam Abdulrahman Bin Faisal University, Al Khobar, Saudi Arabia, 7Siemens Healthineers, Erlangen, Germany, 8School of Medicine and Public Health, University of Newcastle, New Lambton Heights, Australia, 9Department of Neurology, John Hunter Hospital, New Lambton Heights, Australia Keywords: CEST / APT / NOE, Multiple Sclerosis Motivation: Monitoring disease progression in people with relapsing-remitting multiple sclerosis (pw-RRMS) presents a substantial clinical challenge. Conventional MRI often fails to provide molecular biomarkers for pathophysiological changes like myelin protein accumulation indicative of demyelination. Goal(s): The study aimed to validate whether amide proton transfer weighted (APTw) imaging could be a sensitive molecular marker for detecting demyelination in MS lesions. Approach: We conducted APTw imaging at 3T on 24 pw-RRMS, evaluating the signal intensity within MS lesions compared to contralateral normal-appearing white matter (cNAWM) regions. Results: The investigation revealed a statistically significant increase in APTw signal intensity in MS lesions compared to cNAWM regions. Impact: Elevated APTw signal intensity could serve as a
non-invasive molecular biomarker for demyelination, potentially aiding in the
more accurate monitoring of MS disease progression and treatment efficacy. |
| 15:45 | 1098.
 | Assessment of neoadjuvant immunochemotherapeutic response for bladder carcinoma using amide proton transfer weighted MRI: a feasibility study Lingmin Kong1, Qian Cai1, Yanling Chen1, Wenxin Cao1, Bei Weng1, Yan Guo1, and Huanjun Wang1
1The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China Keywords: CEST / APT / NOE, Bladder Motivation: To accurately predict bladder cancer patient neoadjuvant treatment responses is essential and urgent. Goal(s): To investigate the feasibility of amide proton transfer weighted (APTw) and diffusion weighted MRI in evaluating the response of neoadjuvant therapy for bladder cancer. Approach: Histogram analysis features were extracted from pre- and post-treatment APTw and apparent diffusion coefficient (ADC) map. Results: Several imaging biomarkers derived from pretreatment imaging were statistical significant between pathological complete response (pCR, no residual tumor) and non-pCR group (P < 0.05 for all). For the pCR group, APTw values markedly decreased while ADC values noticeably increased at post-treatment MRI (P < 0.05 for all). Impact: This work establishes that APTw MRI holds promise to evaluate bladder cancer tumor responses to neoadjuvant immunochemotherapy
and may be used to guide personalized precision therapy in future. |
| 15:45 | 1099.
 | PET-MR compatible CEST method for imaging of Alzheimer’s Disease. Rodolphe Leforestier1, Ding Xia1, Li Feng2, Carolina Ferreira-Atuesta3,4, Ziwei Xu4, Trey Hedden4, and Xiang Xu1
1Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New-York, NY, United States, 2Center for Advanced Imaging Innovation and Research (CAI2R), New York University Grossman School of Medicine, New-York, NY, United States, 3Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States, 4Department of Neurology, Icahn School of Medicine at Mount Sinai, New-York, NY, United States Keywords: CEST / APT / NOE, CEST & MT Motivation: Current methods of assessing Alzheimer's disease, such as PET scans, are expensive, involve exposure to radiation and have limited resolution. Goal(s): We aim to demonstrate the applicability a novel CEST MRI method to measure the relayed Nuclear Overhauser effect, which may be sensitive to amyloid-β aggregates. Approach: We have developed and tested a radially sampled CEST sequence (ssGraspCEST) that can be acquired on hybrid PET-MRI systems. Results: MCI and AD patients appeared to have narrower distributions of LDNOE and ∆ST(-3.6) and higher values. However, due to the limited sample size at this time, no significant differences were observed between the two groups. Impact: We demonstrated the implementation of a fast, motion-robust CEST method, fully compatible with hybrid PET-MRI systems and particularly suitable for imaging elderly participants who cannot hold still during the scan, which may be useful in future for detecting pathological aggregates. |
| 15:45 | 1100.
 | Orientation independent quantification of macromolecular proton fraction in tissues with suppression of residual dipolar coupling Zijian Gao1, Ziqiang Yu1, Ziqin Zhou1,2, Jian Hou1, Baiyan Jiang1,3, Michael Tim-yun ONG 4, and Weitian Chen1
1Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong, Hong Kong, 2MR Collaboration, Siemens Healthineers Ltd., Hong Kong, Hong Kong, Hong Kong, 3Illuminatio Medical Technology Limited, Hong Kong, Hong Kong, Hong Kong, 4Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, Hong Kong Keywords: Magnetization Transfer, Quantitative Imaging, Macromolecular proton fraction Motivation: The residual dipolar coupling (RDC) can lead to the orientation-dependent measurements in ordered tissues in MRI, potentially confounding their clinical applications. Goal(s): We demonstrate the potential confounding effect from tissue orientation in quantitative magnetization transfer can be suppressed by using a new technique Macromolecular Proton Fraction Mapping based on Spin-Lock (MPFSL). Approach: Applying MPFSL, we can adjust both the resonance frequency offset and the amplitude of spin-lock radiofrequency pulse to achieve a strong effective spin-lock field to suppress RDC, eliminating orientation-dependency of MPF measurement. Human knee specimen experiments conducted verified this finding. Results: The MPF measured using MPFSL shows insensitivity to tissue orientations. Impact: Spin-lock based quantitative
magnetization transfer imaging can achieve orientation-independent
quantification, thus having potential applications in characterization of highly-ordered
tissues such as cartilage and myelin. |
| 15:45 | 1101.
 | Fat-suppressed Ultrashort Echo Time Quantitative Magnetization Transfer (UTE-qMT) MRI via Single-point Dixon Method Soo Hyun Shin1, Hyungseok Jang1, Arya Suprana1,2, Eric Y. Chang1,3, Yajun Ma1, and Jiang Du1,2,3
1Department of Radiology, University of California, San Diego, La Jolla, CA, United States, 2Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States, 3Radiology Service, VA San Diego Healthcare System, La Jolla, CA, United States Keywords: Fat & Fat/Water Separation, Fat Motivation: UTE-qMT imaging has shown potential in probing the molecular composition and microenvironment of short-T2 tissues. Yet fat signals and chemical shift artifacts interfere with morphological contrast and UTE-qMT measurements. Goal(s): To establish a fat suppression method for accurate UTE-qMT imaging. Approach: We adopted the UTE-single point Dixon (UTE-spDixon) method for suppressing fat signals in a series of MT-weighted UTE images of short-T2 tissues. Results: UTE-spDixon successfully separates fat from water without short-T2 signal attenuation and compromising qMT measurement. Impact: The fat/water-separated UTE-qMT
method shown in this study will improve the accuracy of quantifying molecular
compositions of short-T2 tissues. This fat/water separation method
also has the potential to apply to other UTE-based quantitative MR techniques. |
| 15:45 | 1102.
 | Exploration of a low-SAR ihMT-RAGE approach for human whole brain imaging at 7T Timothy Anderson1,2, Lucas Soustelle1,2, Thomas Troalen3, Gopal Varma4, Evgenios N. Kornaropoulos1,2, Maxime Guye1,2, Jean-Philippe Ranjeva1,2, David C. Alsop4, Guillaume Duhamel1,2, and Olivier M. Girard1,2
1Aix Marseille Univ, CNRS, CRMBM, Marseille, France, 2APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France, 3Siemens Healthcare SAS, Courbevoie, France, 4Division of MR Research, Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States Keywords: Magnetization Transfer, Pulse Sequence Design, qMRI ihMT Neuro Brain Motivation: Inhomogeneous Magnetization Transfer (ihMT) is a recent MRI technique that has raised great interest for myelin imaging. Several ihMT protocols have been proposed for whole brain imaging at clinical field strengths. However, ultra-high field (UHF, 7T) translation remains challenging. Goal(s): ln this work we explore ways to perform ihMT at UHF for clinical applications. Approach: A low-SAR ihMT-RAGE sequence is proposed by shortening the ihMT preparation and enabling partial Fourier MT saturation. Results: This original sequence addresses SAR limitations within relatively short scan times, allowing for whole brain 1.2mm isotropic resolution (resp. 1mm) in 12 minutes (resp. 16 min) at 7T. Impact: Ultra-high field ihMT enables high resolution (1mm iso) myelin specific imaging, opening new perspectives for neuroscience and clinical research. Future developments, such as reduced FOV and compressed sensing sequences could bring scan times further down to 5-10 minutes. |
| 15:45 | 1103.
 | BTS POSE: Rapid High Resolution 3D Quantitative MT Imaging using Novel Position Encoding and Parallel Imaging Albert Jang1 and Fang Liu1
1Martinos Center for Biomedical Imaging, Harvard Medical School, Charlestown, MA, United States Keywords: Magnetization Transfer, Magnetization transfer Motivation: Current quantitative MT (qMT) methods have low resolution, limiting their ability to assess tissue microstructure. Goal(s): Introduce a new qMT approach that achieves 3D isotropic high-resolution qMT within a clinically feasible scan time. Approach: BTS POSE applies unique subvoxel-shifts along the acquisition parameter dimension, combined with the BTS MT signal model, to generate MT parameter maps with enhanced resolution. Results: in-vivo results show that BTS POSE 1) enhances the image resolution at no cost of additional scan time, 2) can be combined with parallel imaging to achieve further acqusition acceleration, and 3) generates quantitative maps corresponding well with literature values. Impact: BTS POSE uses position encoding to generate 3D MT parameter maps with enhanced resolution. This enables microstructure assessment of tissues such as myelin, an important biomarker for neurodegenerative diseases. |
| 15:45 | 1104.
 | Refinement of the model and types of data for quantitative Magnetization Transfer (qMT) in brain tissues Gopal Varma1, Aaron K Grant1, Lucas Soustelle2, Olivier M Girard2, Guillaume Duhamel2, and David C Alsop1
1Radiology, Division of MRI Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, 2CNRS, CRMBM, Aix Marseille Univ, Marseille, France Keywords: Magnetization Transfer, Magnetization transfer, qMT, ihMT, brain microstructure Motivation: To improve the accuracy of quantitative Magnetization Transfer (qMT) for interrogation of brain microstructure. Goal(s): To determine: i) the model for qMT that best describes the signal from MT and inhomogeneous MT (ihMT) experiments, and ii) the MT preparations that contribute useful data. Approach: We tested accuracies of the models based on fit quality in-vivo and ex-vivo, comparing ex-vivo qMT at physiological and room temperatures. Data were retrospectively reduced to test the importance of types of MT preparations. Results: We recommend a model with two bound-pool T2 values and use of different MT pulse widths and duty cycles as a result. Impact: Our results will impact the model and data acquired for quantitative Magnetization Transfer (qMT) of brain tissues. Use of a two bound-pool model with distinct T2 values and data inputs with variations in MT pulse width and DC is recommended. |