bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards dense parallel-transmit coil head array: 20-channel dipole and self-decoupled overlapped loop coil array design
Authors: Tseung Melissa Ng , Voon Seng Foong , Wu Menglu , Ipek Özlem
Published: November 2024

Motivation: Traditional dense transmit arrays for 7T imaging face decoupling challenges. A novel approach using self-decoupled coils can potentially overcome these limitations and enhance transmit efficiency. Goal(s): Evaluating an in-house developed 20-element array combining dipoles with self-decoupled overlapped loop coils. Approach: Bench measurements, electromagnetic simulations on phantom and Duke, and MRI acquisitions were conducted to investigate the coil array's performance, assessing individual channel B1+-map efficiencies and decoupling capacitiesResults: Decoupled individual B1+ maps for dipoles, self-decoupled and overlapped loops were obtained for 20-channel head array using MRI measurement and simulations on phantom at 7T. S-matrix results on bench and simulations showed decoupled coil elements. Impact: Searching for alternative and complex coil array design for transmit and receive arrays might enable for more efficient and fast imaging at MRI with high resolution to enable better diagnostics and improved treatment planning.
Comparison of Renal ASL Signal-to-noise Ratio and Corticomedullary Contrast between 3T and 5T MRI
Authors: Kong Xiangwei , Li Yanbin , Wu Mingyan , Zhang Xinzhen , Chen Chen , Jiang Xinyue , Zhang Jeff
Published: November 2024

Motivation: As the most promising method for measuring tissue perfusion, ASL suffers from low signal-to-noise ratio (SNR), with tagged blood typically causing only few percent of signal difference. Goal(s): Explore if the use of 5T MRI could lead to higher SNR and CNR for renal ASL than 3T. Approach: We performed FAIR-EPI on the kidneys of three healthy subjects at 6 inversion times on both 3T and 5T systems. SNR and CNR of difference images were calculated and compared. Results: SNR at 5T was 10.72±2.81, higher than 7.75±2.65 (P = 0.008) at 3T, and CNR were 9.08±4.08 and 6.53±2.14 (P=0.029), respectively. Impact: 5T ASL provides difference images with higher SNR and CNR to allow faster acquisition and better corticomedullary differentiation while maintaining comparable image quality.
Development of the H12 insertable head gradient set designed for 10.5T and optimized for both peripheral nerve stimulation and magnet heating
Authors: Rutt Brian , Roemer Peter , Alejski Andrew , Wade Trevor , Bester Matthew , Ertan Koray , Bratch Alexander , Adriany Gregor , Ugurbil Kamil
Published: November 2024

Motivation: Two interactions between gradient coils and their environment severely limit imaging performance: stimulation of peripheral nerves in human subjects and deposition of heat energy into the superconducting main magnet leading to helium loss or quench. This heating increases significantly for higher B0 and gradient switching frequencies. Goal(s): To address the above limitations by recasting the gradient design problem in a unique way to simultaneously minimize both of these interactions. Approach: Using these new methods, we designed and modeled a head gradient coil: H12. Results: We achieved >1.4 fold PNS improvement and >6 fold lower magnet heating compared to existing state-of-the-art head gradient coils. Impact: Our method allows the design and real-world use of stronger and faster-switching gradients than any in existence, while minimizing peripheral nerve stimulation and excessive magnet heating. The potential impact is especially high for head gradients operating at ultra high field.
Whole brain mapping of NAD at 7T using a 31P 32-channel array coil
Authors: Huang Zhiwei , Widmaier Mark , Wenz Daniel , Emir Uzay , Xin Lijing
Published: November 2024

Motivation: Nicotinamide adenine dinucleotide (NAD) is vital in cellular metabolism, existing in an oxidized (NAD+) and reduced (NADH) form. Its submillimolar concentration in the human brain makes its whole brain mapping challenging. Goal(s): To explore the feasibility of whole-brain NAD mapping in human. Approach: 31P MRSI data were acquired from two volunteers using a 31P 32-channel array coil at 7T. Metabolites were quantified with LCModel. Results: 3D whole-brain NAD maps were acquired with decent SNR within 45min. The measured NAD level and NAD+/NADH ratio were stable across two subjects and aligned with previous single-voxel studies. Impact: Our preliminary data demonstrated the feasibility of whole-brain NAD mapping in humans at 7T, which offers the potential to study regional-specific bioenergetics under different pathological conditions.
Robust single-point UTE Dixon imaging.
Authors: Arrieta Mateo Argudo , Weiss Kilian , Boehm Christof , Feuerriegel Georg , Gersing Alexandra , Karampinos Dimitrios , Van Anh
Published: November 2024

Motivation: A recent approach solved the unwanted phase estimation in single point Dixon imaging using an iterative optimization method. Goal(s): The goal of this work is to properly initialize the previously proposed iterative optimization approach for a more robust water-fat separation. Approach: The iterative optimization method is initialized with the result of the polynomial fit of the signal phase and its derived water and fat signals. Results: By initializing the Gauss Newton method with the result of a polynomial fit of the signal phase, better and more robust water fat separation can be achieved in sUTE Dixon imaging. Impact: The proposed polynomial fit initialization has improved water-fat separation quality and its robustness against regularization parameters while reducing the number of optimization iterations.
Feasibility of Bone Porosity Assessment Using Dual-Echo uTE-MR Fingerprinting
Authors: Barbieri Marco , Liao Congyu , Cao Xiaozhi , Yang Yang , Setsompop Kawin , Kogan Feliks
Published: November 2024

Motivation: Bone porosity is crucial for bone strength, yet standard multi-echo uTE-GRE techniques are too time-consuming for clinical use. uTE MR Fingerprinting (MRF) has not been tested for porosity assessment. If feasible it may offer faster porosity mapping for clinical applications. Goal(s): Assessing the feasibility of using dual-echo 3D-uTE-MRF to measure porosity through simulations and preliminary in vivo testing. Approach: A dual-echo 3D-uTE-MRF sequence was tested for porosity accuracy and precision against standard multi-echo uTE-GRE via simulations. In-vivo, a volunteer's tibia was imaged to demonstrate the technique's preliminary viability. Results: In simulations, dual-echo uTE-MRF outperformed uTE-GRE, but in-vivo applications, despite feasibility, need further development. Impact: We demonstrated the feasibility of a dual-echo uTE MRF approach for measuring bone porosity trough simulation and a preliminary in-vivo acquisition.
3D Turbo-Spin-Echo with VERSE Excitation Improves SNR for Brachial Plexus Magnetic Resonance Neurography
Authors: Cai Xiaoying , Buonincontri Guido , Groß-Weege Nicolas , Kollasch Peter , Akerman Michelle , Stemmer Alto , Tan Ek Tsoon , Sneag Darryl
Published: November 2024

Motivation: The conventional slab-selective 3D TSE approach for brachial plexus magnetic resonance neurography (MRN) has a longer echo spacing for the first refocusing pulse and hence violates CPMG conditions. The signal available can decrease significantly due to field inhomogeneities. Goal(s): We aimed to improve slab-selective 3D TSE for brachial plexus MRN. Approach: We incorporated the variable-rate selective excitation (VERSE) method to shorten the excitation pulse duration and eliminate the need for the first long-echo-spacing refocusing module. Results: The 3D TSE with VERSE excitation achieved higher SNR in both phantom and in-vivo experiments. Impact: The proposed 3D TSE using VERSE excitation improved slab-selective imaging in brachial plexus MRN with higher SNR when compared to the conventional approach.
Explainable concept mappings underlying deep learning brain disease classification
Authors: Tinauer Christian , Sackl Maximilian , Damulina Anna , Achtibat Reduan , Dreyer Maximilian , Pahde Frederik , Lapuschkin Sebastian , Schmidt Reinhold , Ropele Stefan , Samek Wojciech , Langkammer Christian
Published: November 2024

Motivation: While recent studies show high accuracy in the classification of Alzheimer’s disease using deep neural networks, the underlying learned concepts have not been investigated. Goal(s): To systematically identify the concepts learned by the deep neural network for model validation. Approach: Using R2* maps we separated Alzheimer's patients (n=117) from healthy controls (n=219) by using a deep neural network and systematically investigated the learned concepts using Concept Relevance Propagation (CRP). Results: In line with established histological findings, highly relevant concepts were primarily found in and adjacent to the basal ganglia. Impact: The identification of concepts learned by deep neural networks for disease classification enables validation of the models and improves reliability.
TEXTURE ANALYSIS OF CARTILAGE REPAIR TISSUE MATURATION - COMPARISON OF TWO CARTILAGE REPAIR METHODS AND CORRELATION WITH MOCART 2.0
Authors: Janacova Veronika , Juras Vladimir , Szomolanyi Pavol , Sitarcikova Diana , Kirner Alexandra , Trattnig Siegfried
Published: November 2024

Motivation: To monitor patients after cartilage repair surgery, non-invasive imaging techniques are needed. Goal(s): Study aimed to monitor cartilage repair tissue for up to two years post-surgery using GLCM analysis of T2 maps to assess tissue structure and correlate it with the morphological MOCART 2.0 score. Approach: 37 patients underwent either matrix-associated autologous chondrocyte transplantation or microfracturing. ROI’s were drawn onto T2 maps at three time-points. GLCM features, mean T2 and MOCART 2.0 scores were calculated and analysed. Results: We found correlations between GLCM features and the MOCART 2.0 score, with significant changes in texture of the repair tissue over time for transplant patients. Impact: This study reveals a correlation between GLCM and MOCART 2.0 in autologous chondrocyte transplantation and microfracturing. Only chondrocyte transplants showed significant tissue development over time, indicating complex maturation. These findings will impact patient monitoring in clinical trials after cartilage repair.
Fine-Tuning Deep Learning Model For Quantitative Knee Joint Mapping with MR Fingerprinting
Authors: Zhang Xiaoxia , Zibetti Marcelo , Moura Hector , Monga Anmol , Regatte Ravinder
Published: November 2024

Motivation: Estimating MRF quantitative parameters with neural networks (NNs) is faster than dictionary-matching methods (DMs), and it has the advantage of providing continuously distributed parameters. Goal(s): We investigate different aspects of NN training and evaluate its quantitative MRF performance and compare them with DMs. Approach: We exploit how training data sizes, noise levels, and SVD compression sizes affect the MRF performance of the NNs and compare them with DMs. Results: The NN provides a faster way of multi-parametric mapping from NIST/ISMRM phantom and knee joint MRF data sets with comparable performance to DMs. Impact: Well-tuned NN is much more efficient for quantitative MRF, particularly for the knee joint. Besides computational speed, fine-tuning can also increase the performance and robustness to noise.
B1+ Inhomogeneity Correction with Dielectric Padding for Improved MR T2 and T1ρ Quantification in Knee Cartilage and Meniscus at 7 Tesla
Authors: Zbyn Stefan , Lartey Richard , Ok Ahmet , Kim Jeehun , Nemani Ajay , Winalski Carl , Li Xiaojuan
Published: November 2024

Motivation: MR T2 and T1ρ mapping showed great promise for reliable detection and follow-up of knee osteoarthritis, however, B1+ inhomogeneities in knee 7T MRI often lead to signal loss and biased quantification. Goal(s): Present study therefore evaluates the effect of high-permittivity dielectric padding on the B1+ field distribution and the reproducibility of T2 and T1ρ quantification in knee cartilage and meniscus. Approach: Twelve subjects received scan-rescan at 7T to quantify B0, B1+, T2, T1ρ, and reproducibility changes associated with dielectric padding. Results: Dielectric pads positioned over tibia showed improved B1+ homogeneity and reproducibility of T2 and T1ρ quantification in cartilage and meniscus at 7T. Impact: Improved reproducibility of T2 and T1ρ MRI in cartilage and meniscus with dielectric padding at 7T could facilitate its clinical translation at ultra-high field and improve patient’s follow-up for the noninvasive evaluation of new prevention and treatment strategies for osteoarthritis.
Universal Design of Multiphoton Parallel Transmission (MP-pTx) Pulses for Uniform, High-Flip Angle Excitations
Authors: Drago John , Guerin Bastien , Wald Lawrence
Published: November 2024

Motivation: Contrast in high-field MRI is complicated by the spatially non-uniform transmission profile of birdcage coils. Goal(s): We create “universal” pulses for spatially-uniform excitations using multiphoton parallel transmission (MP-pTx). Approach: MP-pTx operates a $$$B_z$$$ shim array in the kHz range to supplement birdcage excitation. We extend this framework to arbitrary flip angles and a universal design (a population of $$$B_1^+$$$ and $$$\Delta B_0$$$ maps) using spinor-domain, Bloch dynamics representation. Results: Universal MP-pTx pulses have 11.3%, and 16.3% flip angle NRMSE for 90º and 180º pulses played on test subjects not used for training, compared to 24.5% and 25.3% with conventional birdcage. Impact: Universal MP-pTx pulses will allow users to mitigate flip angle inhomogeneity present in the brain at 7 T using precomputed pulses without SAR concerns beyond that of a conventional birdcage transmit coil or subject-specific calculations.
T2 Mapping of the Prostate at 7 Tesla: A Feasibility Study
Authors: Bonanno Gabriele , Jung Bernd , Kreis Roland , Schmitter Sebastian , Obmann Verena , Kober Tobias , Hilbert Tom
Published: November 2024

Motivation: T2 relaxometry has shown potential to distinguish cancer from prostate tissue at 3T. Despite potential gains in resolution, it has been little explored at ultra-high field due to challenging B1+ homogeneity and efficiency. Goal(s): To investigate feasibility of prostate T2 mapping at 7T using a robust RF shimming procedure. Approach: We evaluated conventional 2D multi-echo spin echo and an optimized 3D T2-prepared segmented-FLASH sequence. Results: Spin-echo T2 maps showed good quality but required long acquisition times for limited coverage. The T2-prepared FLASH sequence showed similar values while providing higher scan efficiency, lower SAR, and whole-organ coverage at the cost of higher motion sensitivity. Impact: Quantitative T2 mapping at ultra-high field is challenging due to acquisition time and SAR restrictions, especially in the pelvic area. The methods investigated here may be used in future routine to detect and grade prostate cancer.
Single-pulse optogenetic perturbation of thalamo-cortical networks reveals functional architecture of rsfMRI networks
Authors: Xie Linshan , Wang Xunda , Lin Xuehong , Ma Teng , Wen Junjian , Cao Peng , Leong Alex , Wu Ed
Published: November 2024

Motivation: A current overarching challenge in neuroscience is to establish an integrated understanding of brain circuits and networks, particularly the interactions of neural populations across various spatiotemporal scales that give rise to functions and behavior. Goal(s): We posit that dissecting rsfMRI dynamics under direct single-pulse optogenetic modulation of thalamo-cortical networks will reveal critical insights into the functional architecture of rsfMRI networks. Approach: We deployed a computational approach (i.e., Gaussian PCA-HMM) to examine the organization of rsfMRI networks before and upon single-pulse stimulation of thalamus. Results: We demonstrated a significant role of the basal forebrain and hypothalamus in regulating the transient dynamics of rsfMRI networks. Impact: The ability to directly perturb and model dynamics of rsfMRI networks present an unprecedented opportunity to understand brain-wide and higher-order circuits/networks, and their functions, which are difficult to probe using traditional behavioral and/or cognitive tasks and other neuroimaging approaches.
Automated Quality Control for Multi-Vendor, Multi-Centre Renal Imaging Studies
Authors: Daniel Alexander , Craig Martin , Thomas David , Mendichovszky Iosif , Sourbron Steven , Morris David , Priest Andrew , Buchanan Charlotte , Francis Susan
Published: November 2024

Motivation: It is critical that MRI data acquired in multi-site, multi-vendor studies conforms to a standardised acquisition protocol. Goal(s): To develop XNAT tools to highlight scans that do not conform to a specified protocol or are of insufficient quality, enabling rapid correction of errors before future scans. Approach: Multi-site DICOM data is uploaded to XNAT after acquisition, by integrating software tools with this database, investigators are informed if data does not conform. Results: DICOM-QC, a tool to automatically compare DICOM metadata to predefined values, and ImageSNR-QC to calculate image SNR, applied here to a multi-site kidney study. Impact: This work outlines two tools that integrate with XNAT, DICOM-QC and ImageSNR-QC, which can be used by any investigators running large studies to ensure uploaded data conforms to the study protocol, ensuring consistency over sites, vendors, and repeated longitudinal scans.
Gradient impulse response function-based phase compensation for wavelet MR elastography on a compact 3T scanner
Authors: Kang Daehun , Sui Yi , Le Yuan , Yin Ziying , In Myung-Ho , Huston John , Shu Yunhong , Bernstein Matt
Published: November 2024

Motivation: High-performance asymmetric gradient systems have the potential to produce high-spatial-order eddy-current-induced magnetic fields that can impact phase-based applications such as wavelet MRE using large-magnitude motion-encoding bipolar gradient pulses. Goal(s): Removal of the gradient-system-induced high-order phase deviation in the wavelet MRE phase map. Approach: Gradient impulse response functions (GIRFs) can be used to characterize the gradient system. We introduce a GIRF-based phase compensation approach to alleviate the high-order phase deviations resulting from imperfections in the gradient system, along with practical recommendations, including the use of a tailored set of GIRFs. Results: The phase inhomogeneity in wavelet-MRE phase map improved with the GIRF-based compensation. Impact: The proposed GIRF-based phase compensation approach offers the potential to enhance phase image quality and accuracy, addressing imperfections in the gradient system, which is a challenge not fully resolved by alternative methods like concomitant field correction and pre-emphasis gradient modification.
Optimizing MR Fingerprinting Pulse Sequences for Neonates and Across Age Ranges
Authors: Hu Siyuan , Qiu Zhilang , Zhu Yuran , McGivney Debra , Ma Dan
Published: November 2024

Motivation: Due to significantly different relaxation times and image contrasts between neonate and adult brain, MR sequences optimized for adults are sub-optimal and may produce measurement bias in pediatric scans. Goal(s): Optimizing MR fingerprinting pulse sequence for neuroimaging across age ranges. Approach: We predicted and minimized measurement errors using the systematic error index model with a digital neonate brain phantom to optimize MRF sequence parameters. Optimized sequences were compared against an adult-optimized sequence via simulation and in vivo scans. Results: Optimized sequences showed improved image quality and accuracy for infant scans and maintained accuracy for adult scans in both simulation and in vivo experiments. Impact: We present the first application of the systematic error index model for MRF sequence optimization for brain scans across age ranges to achieve high measurement accuracy with reduced scan time.
Comparison of ground-truth-free deep learning approaches for accelerated quantitative parameter mapping
Authors: Fujita Naoto , Yokosawa Suguru , Shirai Toru , Terada Yasuhiko
Published: November 2024

Motivation: Ground-truth-free (GT-free) deep learning (DL) approaches are expected to lower the cost of training DL models in accelerated quantitative MRI, but their performance has not been well compared to supervised approaches, and their application to quantitative MRI is still limited. Goal(s): Evaluation of the effectiveness of GT-free approaches in quantitative MRI. Approach: Three quantitative MRI methods (variable flip angle, multi-slice multi-echo, double echo steady state) were used to compare model-based DL architectures with three learning schemes: supervised learning, self-supervised learning, and zero-shot self-supervised learning in multiple acceleration factors. Results: GT-free deep Learning approaches had high performance comparable to SL in many cases. Impact: In this study, we compared GT-free approaches with SL and showed that they had high performance comparable to SL in many cases. These results indicate that GT-free approaches are applicable to a variety of sequences in accelerated quantitative MRI.
Evaluation of slow flow measurement with low b-value diffusion tensor imaging using fluid phantoms in comparison with 4D-flow
Authors: Oki Tatsuya , Bito Yoshitaka , Hiratsuka Shinnosuke , Yoshimura Masahiro , Watanabe Yoshiyuki
Published: November 2024

Motivation: Is low b-value diffusion tensor imaging (low-b DTI) useful for analyzing cerebrospinal fluid flow, which is a slow and complex flow that is difficult to measure?Goal(s): To validate low-b DTI for analyzing the slow flow. Approach: To compare low-b DTI with 4D-flow in the fluid phantom where water flowed at a constant slow rate. Results: A strong correlation between the mean diffusivity of Low-b DTI and the mean square of deviation of velocity of 4D-flow, which is supported by the theory that these correlate in laminar flow. Impact: If low b-value diffusion tensor imaging is useful for analyzing slow and complex flows of cerebrospinal fluid, it should contribute to understanding the pathogenesis of various diseases in which impaired cerebrospinal fluid clearance system may be part of the etiology.
Tuned Exchange Imaging (TEXI) – A modified Filter-Exchange Imaging pulse sequence for applications with thin slices and restricted diffusion
Authors: Lasic Samo , Chakwizira Arthur , Lundell Henrik , Westin Carl-Fredrik , Nilsson Markus
Published: November 2024

Motivation: Thin slices in filter-exchange imaging lead to biased exchange rates, as thin slices require strong crushers. No current approach accounts for crushers in the presence of restricted diffusion. Goal(s): We set to address the bias in FEXI due to the influence of strong crushers and restricted diffusion. Approach: Tuned exchange imaging (TEXI) relies on gauging exchange and restriction weighting. We modify FEXI to ensure constant restriction weighting also with strong crushers. The accuracy of exchange mapping was evaluated using Monte Carlo simulations. Results: TEXI yields consistent exchange rates independent of slice thickness and restriction size even if strong crushers are used. Impact: TEXI could be useful to maximize exchange sensitivity and specificity with thin slices and in the presence of restricted diffusion.
Neurite Beading Model of Acute Stroke from Tensor-Valued Diffusion Encoding Predicts Diffusion Time Effects with Oscillating Gradients
Authors: Zhou Mi , Stobbe Robert , Budde Matthew , Beaulieu Christian
Published: November 2024

Motivation: Can two different diffusion experiments (tensor-valued encoding and oscillating-gradient-spin-echo) support the role of axon beading for diffusion restriction in acute ischemic stroke?Goal(s): To evaluate whether tensor-valued diffusion encoding yields an axon beading model that predicts experimental ischemic changes of diffusivity measured with OGSE. Approach: Tensor-valued and OGSE/PGSE diffusion MRI were measured in the same acute stroke patients. Monte Carlo simulations were used to assess the links between these two independent measurements. Results: The tensor-valued derived beading model predictions were in general agreement with independent experiments of less diffusivity reduction with OGSE than PGSE within stroke lesions. Impact: Novel diffusion MRI sequences such as tensor-valued encoding and oscillating-gradient-spin-echo are complementary methods that point to the same microstructural basis (i.e. beading and elevated intra-cellular volume fraction) for the clinically useful diffusion reduction in acute ischemic stroke.
Right ventricular electromechanical discoordination predict long-term clinical outcomes in patients with pulmonary arterial hypertension
Authors: Li Wen , Chang Xu-yang , Zhang Xian-chang , Qian Yu-ling , Wetzl Jens , Gu Qing , He Jian-guo
Published: November 2024

Motivation: Non-invasive and accurate evaluation of right ventricular (RV) function in pulmonary arterial hypertension (PAH) is of urgent need in clinical practice. Goal(s): To investigate the clinical implications of RV electromechanical dyssynchrony which were non-invasively derived from cardiac MRI. Approach: Calculate systolic stretch fraction (SSF) and diastolic relaxation fraction (DRF) based on strain MRI and test their prognostic values in an observation prospective PAH cohort. Results: SSF-RV-Longitudinal could independently predict the clinical worsening. Impact: The present study first reported SSF-RV-Longitudinal as a novel parameter to evaluate RV function, which could predict the clinical worsening in PAH patients.
Phenotypic clustering using cardiovascular magnetic resonance for risk stratification in beta-thalassemia major
Authors: Meloni Antonella , Pistoia Laura , Vallone Antonino , Righi Riccardo , Restaino Gennaro , Schicchi Nicolò , Grassedonio Emanuele , Renne Stefania , Riva Ada , Sanna Paola Maria Grazia , Benni Monica , Cademartiri Filippo , Positano Vincenzo
Published: November 2024

Motivation: Machine learning algorithms provide a means to uncover hidden patterns within complex and heterogeneous datasets. Goal(s): We aimed to identify phenogroups among patients with β-thalassemia major (TM) using an unsupervised clustering approach based on demographic, clinical, and CMR data. Approach: We considered 356 β-TM patients who underwent MR for the assessment of iron overload, biventricular function and atrial, and replacement myocardial fibrosis. Results: We identified three mutually exclusive phenogroups characterized by different biventricular function parameters and frequency of replacement myocardial fibrosis and by a different prospective risk of cardiovascular complications. Impact: In TM, unsupervised clustering integrating routinely measured CMR parameters conveys the potential to significantly impact patient care and improve cardiovascular outcomes by enabling early detection of cardiac remodeling and damage, as well as improved risk stratification.
Enhancing myocardial scar detection by combining fat-water separation with bright- and black-blood late gadolinium enhancement imaging
Authors: Villegas-Martinez Manuel , de Villedon de Naide Victor , Ben Lala Ilyes , Narceau Kalvin , Nogues Victor , Dournes Gaël , Bazin Claire , Maes Jean-David , Sridi Soumaya , Stuber Matthias , Cochet Hubert , Bustin Aurélien
Published: November 2024

Motivation: Combined bright- and black-blood late gadolinium enhancement has shown potential for scar detection.However, accurate differentiation between scar and fat tissue in these images can pose a challenge. Goal(s): To assess the SPOT-Dixon sequence, a joint bright- and black- blood methodology in combination with a two-point Dixon approach to improve myocardial scar detection and delineation. Approach: The proposed sequence was tested in 13 patients with suspected cardiovascular diseases and the results were compared to those from reference sequences. Results: The SPOT-Dixon sequence was able to reliably delineate scar tissue within the myocardium and differentiate it from fat in its proximity. Impact: The proposed sequence combining the SPOT sequence and a two-point Dixon method gives reliable images of the myocardial scar and the fat tissue surrounding it, providing a valuable diagnostic advantage and potentially improving the accuracy of cardiovascular assessments.
MRI2Qmap: compressed-sampled multiparametric quantitative MRI reconstruction using learned spatial priors from multimodal MRI datasets
Authors: Golbabaee Mohammad , Cencini Matteo , Pirkl Carolin , Menzel Marion , Tosetti Michela , Menze Bjoern
Published: November 2024

Motivation: Deep learning excels at compressed-sensing image reconstruction given large training datasets. Applying this paradigm to accelerated quantitative MRI, including magnetic resonance fingerprinting (MRF), is challenging because quantitative imaging datasets for training are scarce. Goal(s): Can we overcome this limitation using new sources of training data from routine, largely available weighted-MRI images?Approach: We introduce MRI2Qmap, a plug-and-play quantitative image reconstruction algorithm based on deep image denoising models pretrained on large multimodal weighted-MRI datasets. Results: We showed, for the first time, that spatial/structural priors learned from independently-acquired datasets of routine weighted-MRI images can be effectively used for quantitative MRI image reconstruction. Impact: Thanks to the widespread use of MRIs, our approach could enable much larger datasets to be used for training potentially enhanced AI models for fast quantitative MRI/MRF image reconstruction.
Association of Patella Bone Shape and MR-Diagnosed Patellar Tendinopathy with Patellar Cartilage T2/T1ρ in Elite Basketball Players
Authors: Schmidt Andrew , Rubin Elka , Little Mackenzie , George Madison , Zheng Hayden , Young Katherine , Desai Arjun , Kogan Feliks , Majumdar Sharmila , Potter Hollis , Gold Garry , Gatti Anthony
Published: November 2024

Motivation: Patellar tendinopathy (PT) is a common injury in basketball that can lead to early retirement. Basketball influences bone shape and cartilage composition, yet the association between these factors and PT is unknown. Goal(s): We examined the association between PT, bone shape, and patellar cartilage composition in collegiate basketball players. Approach: We developed a measure of bone shape indicative of PT and investigated whether PT-associated bone shape is associated with patellar cartilage T2/T1ρ. Results: We effectively separated grades of PT using bone shape and identified bone shape features associated with PT. We found patellar cartilage composition is independent of PT and bone shape. Impact: We developed a measure to identify varying grades of PT based on bone shape in collegiate basketball players. Future work will determine the association of our PT-bone shape score with MR-identifiable measures to identify athlete specific PT risk factors.
Unbiasing the spherical variance of a diffusion-weighted MR signal: An application to intra-axonal T2 estimation
Authors: Pieciak Tomasz , París Guillem , Vega Antonio Tristán , Aja-Fernández Santiago
Published: November 2024

Motivation: The spherical variance (SV) from multiparametric diffusion MRI acquisitions enables the estimation of the axonal T2 relaxation time. The SV is prone to a noise-induced bias due to positively skewed Rician statistics, leading to overestimation in the axonal T2 parameter. Goal(s): To derive a method to mitigate the Rician bias in the SV parameter map. Approach: A closed-form formula to remove the Rician bias from the SV has been analytically derived and verified with in silico and in vivo data. Results: The bias-corrected SV reduces the estimation error compared to the SV, translating to a less pronounced misestimation in the axonal T2 parameter. Impact: The SV is a practical parameter to infer the properties of restricted compartments with diffusion MRI. This work shows a formula to remove the Rician bias from the SV. The correction can be used for other SV-based diffusion MRI measures.
Ultra-high gradient diffusion MRI on Connectome 2.0 reveals time-dependent diffusion and water exchange in human gray matter
Authors: Chan Kwok-Shing , Ma Yixin , Lee Hansol , Marques José , Olesen Jonas , Coelho Santiago , Novikov Dmitry , Jespersen Sune , Huang Susie , Lee Hong-Hsi
Published: November 2024

Motivation: In vivo mapping of exchange between intra-neurite and extracellular water in gray matter is challenging, as the required strong diffusion weighting significantly reduces the signal-to-noise ratio. Goal(s): We aim to demonstrate the feasibility of in vivo neurite exchange imaging using the state-of-the-art Connectome 2.0 scanner equipped with high-performance gradient system (Gmax=500mT/m, (dG/dt)max=600T/m/s). Approach: We acquired in vivo diffusion MRI measurements with multiple diffusion times (13-30ms) up to b-values of 17.5ms/μm2 on 5 human subjects. Anisotropic Kärger model (NEXI/SMEX) was used to estimate the exchange time from the diffusion data. Results: The exchange time across the cortical ribbon is around 16ms. Impact: The high performance gradient system on the Connectome 2.0 scanner enables in vivo mapping of water exchange time in gray matter, providing a tool to study neurite permeability in the healthy human brain and a variety of neuropsychiatric disorders.
Robust double-diffusion-encoded spectroscopy (DDES) in the human brain on a clinical MR scanner using metabolite-cycling
Authors: Döring André , Mosso Jessie , Kreis Roland , Dowell Nicholas , Jones Derek , Najac Chloé , Hall Matt , Lundell Henrik , Xin Lijing , Ronen Itamar
Published: November 2024

Motivation: Double-Diffusion-Encoded Spectroscopy (DDES) provides multiple metrics of cell-specific morphology in a single MR experiment but is prone to motion-induced signal distortions. Goal(s): To obtain robust microstructural metrics of cell-type specific diffusion in different brain regions. Approach: We combine DDES with metabolite-cycling (MC) and motion-compensation (MoCom) to correct for signal distortions in post processing. Results: MoCom improves DDES data quality and reproducibility and allows metabolite specific diffusion metrics to be obtained on clinical 3T MR scanners. Impact: The implementation of robust Double-Diffusion-Encoded Spectroscopy (DDES) on clinical MR scanners can shed new light on cellular microstructure in the healthy and pathological brain.
Isotropic diffusional kurtosis as a marker of glial cell content and diversification during brain maturation
Authors: Rahman Naila , Hamilton Jake , Xu Kathy , Brown Arthur , Baron Corey
Published: November 2024

Motivation: Healthy rodent brain maturation research remains limited, although rodents are a predominant study model, which motivates further study to exclude confounds of developmental changes from pathophysiological interpretations. Goal(s): Our goals were to investigate how microstructural MRI metrics change over the course of brain maturation and disentangle what changes in these metrics may indicate on a neurobiological level. Approach: 11 mice were scanned at 9.4T between 3-8 months of age, with histology (n=4) performed at 3 and 8 months. Results: Total diffusional kurtosis and myelin-specific metrics showed significant increases over time, paired with increased isotropic kurtosis and increased histological oligodendrocyte and astrocyte content. Impact: This work shows that there are ongoing microstructural changes even after mice are considered “adults”, detectable by isotropic kurtosis. We provide new interpretations of diffusion MRI changes during brain maturation, with evidence of the underlying mechanisms impacting isotropic kurtosis.
Measuring intravoxel incoherent motion (IVIM) using Spherical Tensor Encoding (STE) diffusion MRI
Authors: Wang Tianchi , Dong Tanxin , Zang Han , Zhu Jiayu , Lin Hai , Yuan Jianmin , Zhu Fengting , Xie Chuanmiao , Fan Qiuyun
Published: November 2024

Motivation: The assumption of Gaussian diffusion in the extravascular space in the IVIM model does not necessarily hold, especially for neuronal tissues. Goal(s): To mitigate the impacts on IVIM estimation from complicated extravascular space diffusion such as in the crossing-fiber tissues. Approach: We employed Spherical Tensor Encoding (STE) in place of the Linear Tensor Encoding (LTE) as in the conventional Stejskal-Tanner experiment to eliminate the orientational dependence of diffusion signal. Results: The feasibility of the microscopic IVIM based on STE experiments was demonstrated in both healthy and diseased participants, with expected contrasts according to known anatomy/pathology. Impact: A new framework of IVIM measurement was proposed based on the Linear Tensor Encoding diffusion experiment. The proposed approach can achieve diffusivity estimates in one excitation, which will otherwise require acquisition of multiple diffusion weighting directions.
Difference in the spatial pattern of brain atrophy associated with Alzheimer’s and LATE neuropathology
Authors: Saifullah Khalid , Ridwan Abdur Raquib , Bennett David , Schneider Julie , Arfanakis Konstantinos
Published: November 2024

Motivation: Alzheimer’s disease neuropathologic change (AD-NC) and limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) are common age-related pathologies and are associated with brain atrophy, especially in the medial temporal lobe. However, the difference in atrophy patterns associated with the two pathologies is not well known. Goal(s): To investigate the difference in brain atrophy patterns associated with AD-NC and LATE-NC. Approach: Ex-vivo MRI and detailed neuropathology were combined in a large number of community-based older adults that came to autopsy. Results: LATE-NC stages 2 or 3 are associated with more atrophy in the anterior portion of the hippocampus compared to moderate or severe AD-NC. Impact: Atrophy in the anterior portion of the hippocampus is more severe with LATE-NC stages 2 or 3 than with moderate or severe AD-NC.
Hyperintense globus pallidus rim sign on 7T MRI is a novel biomarker of neurological Wilson’s disease
Authors: Su Dongning , Zhang Zhijin , Zhang Zhe , Zheng Sujun , Yao Tingyan , Dong Yi , Zhu Wanlin , Wei Ning , Suo Yue , Liu Xinyao , Zhao Huiqing , Wang Zhan , Ma Huizi , Li Wei , Zhou Junhong , Lam Joyce , Wu Tao , Li Yuan , Dusek Petr , Stoessl A. Jon , Wang Xiaoping , Jing Jing , Feng Tao
Published: November 2024

Motivation: Excessive subcortical metal deposition seen on susceptibility imaging has suggested a characteristic pattern in neurological Wilson’s disease (NWD). Goal(s): To develop a novel imaging biomarker of NWD using 7T SWI. Approach: WD patients, monoallelic ATP7B variant carriers, health controls, and patients with comparable clinical or imaging manifestations were recruited for development of a novel biomarker of NWD and exploratory comparative analysis. All underwent 7T SWI with quantitative susceptibility mapping and principal component analysis performed. Results: The novel biomarker of NWD termed "hyperintense globus pallidus rim sign" showed high diagnostic accuracy. It revealed a special metal deposition pattern in the lenticular nucleus in NWD. Impact: A novel imaging biomarker of neurological Wilson’s disease (NWD) termed "hyperintense globus pallidus rim sign" could aid the diagnosis and monitoring of NWD.
Development of a Compact Head-only Scanner with a Window and Shoulders Outside its Vertical Bore.
Authors: Froelich Taylor , Theilenberg Sebastian , Bailey Joseph , DelaBarre Lance , Suddarth Steve , Pizetta Daniel , Martins Mateus , Vidoto Edson , Shang Yun , Lagore Russell , Nixon Terence , Strupp John , Olatunji Jamal , Szmigiel Mathieu , Hunter Mark , Ramírez Edgar , Lemke Mailin , Kumaragamage Chathura , Weijers Huub , Gonzalez R , Vaughan J. Thomas , de Graaf Robin A. , Juchem Christoph , Tannús Alberto , Parkinson Ben , Garwood Michael
Published: November 2024

Motivation: MRI has evolved into an indispensable tool, but remains inaccessible to much of the world’s population. Goal(s): To build a compact, low-cost, mid- to high-field MRI system capable of producing diagnostic-quality images. Approach: A complete redesign of MR scanner architecture and key technologies; including a compact high temperature superconducting magnet, multi-coil gradient array, and digital spectrometer. The system required extensive testing prior to integration and initial imaging. Results: Initial experiments produced high-resolution images despite using an extremely inhomogeneous magnetic field from the compact 0.7 tesla magnet. Impact: This work represents a significant milestone within the MRI community to address the problems in accessibility and under-utilization facing MRI today. By focusing on ways to develop portable, low-cost systems, the accessibility of this imaging modality can increase substantially.
Low-frequency magnetic signal detection using stimulus-induced rotary saturation sequence in ultra-low field MRI
Authors: Oida Takenori , Moriya Takahiro , Saito Akinori , Ueda Hiroyuki , Ito Yosuke , Suyama Motohiro
Published: November 2024

Motivation: Realization of biomagnetic measurement using MRI with high spatial resolution. Goal(s): Detection of low-frequency magnetic signals below 50 Hz in ultra-low field MRI (ULF-MRI). Approach: Magnetic signal detections were performed by stimulus-induced rotary saturation (SIRS) sequence in ULF-MRI. As magnetic signals, reference magnetic fields with 225 nTpp in amplitude and 10, 15, ..., 70 Hz in frequency were applied to the bottle phantom. Results: The signal reduction of approximately 20% were observed when the reference magnetic field between 30 Hz and 45 Hz were applied. This indicates that low-frequency magnetic signals can be detected by the SIRS sequence in ULF-MRI. Impact: We demonstrate the feasibility of biomagnetic measurement below 50 Hz such as brain activity first time by realizing low-frequency magnetic signal detection using stimulus-induced rotary saturation sequence in ULF-MRI with 7 mT in B0.
Effect of nicotinamide riboside on glutamate in a 5XFAD mouse model of Alzheimer’s disease as measured by glutamate CEST MRI
Authors: Swain Anshuman , Soni Narayan , Nanga Ravi Prakash Reddy , Davis James , Juul Halvor , Baur Joeseph , Reddy Ravinder
Published: November 2024

Motivation: Nicotinamide riboside (NR) supplementation has increased in popularity for treating neurodegenerative diseases and is attributed to elevated NAD+ levels. Effective monitoring of NR-mediated changes may highlight metabolic underpinnings of NR in dementia. Goal(s): This study uses glutamate-CEST MRI to monitor changes in glutamate levels following NR supplementation in wild-type and 5XFAD mouse models of AD. Approach: Mice (WT and AD) were treated with NR or a vehicle (placebo) for 12 weeks followed by GluCEST MRI. Results: There was a significant GluCEST increase in AD mice compared to WT. Following NR, GluCEST decreased in AD mice, primarily in the hippocampus. Impact: NR supplementation may help alleviate excitotoxicity in AD, thereby preventing neuronal cell death/degeneration. GluCEST provides an effective method for assessing changes in glutamate levels, allowing for monitoring excitotoxicity in patients presenting symptoms of AD and the effects of NR treatment.
Common coordinate framework of infant marmoset brain based on ultra-high-resolution diffusion MRI
Authors: Zhu Tianjia , Kim Juri , Wu Fengxia , Ouyang Minhui , Sousa Andre , Levine Jon , Kriegstein Arnold , Huang Hao
Published: November 2024

Motivation: Integrating a spatially resolved and molecularly defined cell atlas with studies of developing brain function, neurophysiology, and behavior will require an anatomical common coordinate framework (CCF). Ultra-high-resolution diffusion-MRI (dMRI) improves anatomical determinations and provides rich contrasts and microstructural information. Goal(s): To build the first dMRI-based anatomical CCF for infant marmoset brains. Approach: Ultra-high resolution dMRI at 9.4T was performed on a 10-month-old marmoset brain. Anatomical regions were delineated. Results: An ultra-high-resolution CCF for the infant marmoset brain at isotropic 0.1mm diffusion MR imaging resolution, characterized by comprehensive labels of fine neuroanatomical structures and coordinate framework. Impact: The first infant marmoset brain CCF will allow integrating spatially resolved, molecularly defined cell atlas with studies of developing brain function, neurophysiology, and behavior. It will provide insights into evolution and human-specific features of brain development relevant to brain disorders.
Using a standard MRI atlas with non-equitable sex representation introduces spurious sex effects
Authors: Martinez-Tazo Patricia , Santos Alexandra , Selim Mohamed , Espinós-Soler Elena , De Santis Silvia
Published: November 2024

Motivation: Overcoming sex bias in preclinical research requires unbiased tools. Equitable sex representation in the creation of the atlas is seldom achieved, but failing to do so might introduce bias in the analysis. Goal(s): Our goal was to create a mouse MRI template that includes animals of both sexes, incorporating both structural and diffusion contrasts, and then compare it with a single-sex template. Approach: We scanned a large cohort of mice, including both sexes, to generate a template and registered the Allen annotation to it. Results: Using single-sex templates generates spurious sex differences that are not present when using resources with equitable sex representation. Impact: The MouseX DW-Allen Atlas is the first mouse MRI template that adopts the Allen annotation and is built with both sexes. It fills an important gap in preclinical imaging research, promotes gender equality, and fosters collaborative and multi-approach science.
Sex- and brain region-specific 1H MRS neurometabolic profiles in young rats with hepatic encephalopathy
Authors: Mosso Jessie , Pierzchala Katarzyna , Sessa Dario , Mitrea Stefanita , Gerossier Estelle , Alves Brayan , Braissant Olivier , McLin Valérie , Cudalbu Cristina
Published: November 2024

Motivation: The lack of preclinical studies on potential sex-differences in the pathophysiology of hepatic encephalopathy (HE) prevents a comprehensive understanding of the disease. Goal(s): To study the effect of sex on the neurometabolic profiles measured with 1H MRS. Approach: We compared 1H MRS metabolite concentrations in the hippocampus and striatum of young male versus female rats with HE. Results: We observed overall stronger neurometabolic effects of the disease on male versus female HE rats, including weight loss and decrease in brain antioxydants levels (Asc, GSH), likely hampering the capacity of male animals to counteract oxidative stress, important player in the pathophysiology of HE. Impact: Sex-differences, often overlooked in preclinical studies, investigated here showed distinct 1H MRS neurometabolic profiles in female versus male rats with hepatic encephalopathy (HE), opening a new window of investigation for patients with HE.
NaGdF4-Based Magnetic Resonance Nanoprobes for Qualitative Inflammation Imaging in Glioma: Hot or Cold?
Authors: Wang Jing , Guo Haiyan , Luo Yu , Ni Dalong
Published: November 2024

Motivation: It is in urgent need to develop an imaging method to reveal the intrinsic ‘cold’ or ‘hot’ status of tumor microenvironment for glioma patients, which would offer guidance for planning therapeutic regimen, and thus maximize the therapeutic efficacy and reduce unnecessary treatment. Goal(s): To visualize the inflammatory status of glioma tumor microenvironment non-invasively using myeloperoxidase responsive NaGdF4-based nanoprobes under MRI. Approach: Different glioma models with different inflammatory status were created and imaged with our nanoprobes under 11.7 T at T1WI (n = 6 each group). Results: MPO-enriched ‘hot’ gliomas showed patchy hypointense T1 signal while MPO-rare ‘cold’ gliomas presented moderate hyperintensity in T1WI. Impact: Depending on the level of MPO in tumor microenvironment, nanoprobes will get self-assembled in various degree, thus altering T1 relaxation time. By using this, it is promising to monitor the tumor inflammatory status for glioma patients thus guide clinical treatment.