bluuebunny/crossref_metadata_2025 huggingface dataset:
Large-shift, Rapid Exchange Endogenous CEST Contrast for Reporter Gene Product Design
Authors: Korenchan David , Scalzitti Nicolas , McMahon Michael , Gilad Assaf , Farrar Christian
Published: November 2024

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.
Magnetic Resonance Fingerprinting of the Chemical Exchange Relayed Nuclear Overhauser Effect In Vivo (rNOE-MRF)
Authors: Power Inbal , Rivlin Michal , Navon Gil , Perlman Or
Published: November 2024

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.
Fat-suppressed Ultrashort Echo Time Quantitative Magnetization Transfer (UTE-qMT) MRI via Single-point Dixon Method
Authors: Shin Soo Hyun , Jang Hyungseok , Suprana Arya , Chang Eric , Ma Yajun , Du Jiang
Published: November 2024

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.
BTS POSE: Rapid High Resolution 3D Quantitative MT Imaging using Novel Position Encoding and Parallel Imaging
Authors: Jang Albert , Liu Fang
Published: November 2024

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.
Functional MRI test-retest reliability during deep brain stimulation in Parkinson’s disease
Authors: Deutsch Skyler , Vu Katelyn , Fuentes Andrea , Wang Sarah , Martin Alastair , Ostrem Jill , Starr Philip , Wang Doris , Bledsoe Ian , Morrison Melanie
Published: November 2024

Motivation: fMRI studies are advancing DBS biomarker development, but data reproducibility is unclear. Goal(s): To evaluate resting-state fMRI reliability in 16 patients with DBS for Parkinson’s disease. Approach: fMRI was repeated for DBS-ON and DBS-OFF conditions. Test-retest connectomes were correlated to measure reproducibility and compared across DBS conditions and clinical parameters. Signal reproducibility around the leads was also explored. Results: Stimulation reduced reproducibility around the leads and across multiple networks, differing by brain target. Patients with less tremor and/or more rigidity and bradykinesia, and relative lower symptom and brain response to DBS had more reproducible functional connectivity. Impact: The results enhance our understanding of the reliability of resting-state fMRI derivatives in the presence of DBS leads and during stimulation. Realizing the reliability of these data is critical to clinical translation of fMRI-based biomarkers to improve the DBS strategy.
Quantitative susceptibility mapping of the common marmoset brain at 9.4 T
Authors: Dadarwal Rakshit , Boretius Susann
Published: November 2024

Motivation: Quantitative Susceptibility Mapping (QSM) is still not widely employed in non-human primates (NHP). Although it has been recently applied to cynomolgus and rhesus macaques, little attention has been given to other NHPs like marmosets. Goal(s): Our goal was to establish QSM in marmosets at 9.4 T. Approach: We conducted high-field MRI on 33 healthy marmosets to achieve superior spatial resolution and sensitivity. We evaluated the contrast-to-noise ratio in the QSM map for four subcortical structures and generated cortex intensity profiles. Results: In the marmoset brain, QSM provided excellent contrast of subcortical structure, various white matter tracts, and the cortex. Impact: Establishing QSM in marmosets may be helpful to those interested in comprehending brain tissue structure and organization, refining brain parcellation, and facilitating procedures like MRI-guided stereotactic surgery, injections, and precise neuronal targeting.
gNET: gSlider Self-Supervised Neural Network for Accelerated Reconstruction of Super-resolution Diffusion MRI
Authors: de Oliveira Kobayashi Caique , Jun Yohan , Cho Jaejin , Wang Xiaoqing , Li Zihan , Tian Qiyuan , Bilgic Berkin
Published: November 2024

Motivation: gSlider utilizes radio-frequency encoding to acquire high and isotropic resolution brain diffusion-MRI with high SNR. However, this comes at the cost of prolonged acquisition time, which also increases the sensitivity to motion. Goal(s): This work proposes gSlider Network (gNET) to accelerate gSlider from acquisitions with jointly subsampled RF- and q-space. Approach: The self-supervised model was trained and tested on a 1mm3 resolution BUDA-gSlider dataset (Tacq = 32 min). FSL and the DIMOND self-supervised were used to estimate the diffusion parameters. Results: gNET achieved an acceleration factor of R=2 and, when combined with DIMOND, reached a total R=4-fold (Tacq = 8 min). Impact: gNET facilitates super-resolution dMRI by reducing the acquisition time by 4-fold with high fidelity. Its application may propel new discoveries in the neuroscientific field and the clinical translation of the gSlider framework.
Diffusion MRI-based Estimation of Cortical Architecture via Machine Learning (DECAM) enhanced by cortical label vectors
Authors: Zhu Tianjia , Ouyang Minhui , Liu Xuan , Liu Risheng , Huang Hao
Published: November 2024

Motivation: Advanced diffusion MRI (dMRI) has enabled noninvasive assessment of cortical measures conventionally only available from neuropathology. Analytical dMRI models are limited by restrictive model assumptions. Goal(s): In this study, we develop Diffusion-MRI based Estimation of Cortical Architecture using Machine-learning (DECAM), a translational framework of “noninvasive neuropathology” that can quantify cortical architecture based on dMRI. Approach: DECAM incorporates cortical label vectors to address the challenge of achieving perfect MRI-histology registration in primate brains due to their complex morphology. Results: By providing high-fidelity, reproducible whole-brain soma density maps validated with histology, DECAM paves the way for data-driven noninvasive histology for potential applications such as Alzheimer’s. Impact: DECAM is the first translational framework and robust pipeline that addresses the challenge of estimating high-fidelity whole-brain soma density in primate brains with complex morphology. DECAM paves the way for data-driven noninvasive histology for potential applications such as Alzheimer’s.
Efficient T2 and diffusion weighted imaging using the multiple-echo steady-state (MESS) sequence with a 3D PROPELLER acquisition
Authors: Zijlstra Frank , Zaitsev Maxim , While Peter
Published: November 2024

Motivation: The multiple-echo steady-state (MESS) sequence extends double-echo steady state and efficiently measures multiple images with different contrasts. Because diffusion contrasts are important in clinical imaging, this study aims to include strong diffusion weighting in the MESS sequence. Goal(s): To extend the MESS sequence to provide distortion-free, high-resolution 3D T1-, T2- and diffusion-weighted imaging. Approach: The DW-MESS sequence utilizes a 3D EPI-PROPELLER acquisition to acquire 32 echoes per repetition. An incoherent non-Cartesian k-space trajectory enables reconstruction of individual echoes. Results: The DW-MESS images show contrasts comparable to SE-EPI with anterior-posterior diffusion encoding. Artifacts are present in other diffusion directions, and require further phase corrections. Impact: This study enables stronger diffusion-weighting in DESS-type sequences in addition to T1- and T2-weighting. The incoherent k-space trajectory allows reconstruction of a B0-map and coil-sensitivities, and could allow T2* and susceptibility quantification. This provides new opportunities for efficient multi-parametric imaging.
Intra-tumor heterogeneity based on synthetic MRI in predicting Ki-67 status of nasopharyngeal carcinoma
Authors: Ren Huanhuan , Zhang Jiuquan , Huang Junhao , Huang Yao , Liu Daihong , Zhang Jing , Tan Yong , Yu Hong , Nie Lisha
Published: November 2024

Motivation: The staging and prognosis of nasopharyngeal carcinoma (NPC) remain significant challenges, with potential correlations to the Ki-67 proliferation status. Goal(s): To assess and analyze an ITH model based on pre-treatment synthetic MRI (SyMRI) for predicting Ki-67 status in patients with pathologically confirmed NPC. Approach: Twenty-eight NPC patients who underwent pre-treatment SyMRI. SyMRI data were processed to generate T1, T2, and PD maps. The ITHscore, derived from quantitative parameter maps, was utilized to establish models for predicting Ki-67 status based on clinical data. Results: The ITHscore, based on quantitative parameter maps, demonstrated promise as an imaging marker for predicting Ki-67 status in NPC. Impact: The ITHscore derived from SyMRI holds potential as a non-invasive imaging marker for predicting Ki-67 status, which can have clinical implications in the management of NPC.
Quantitative phase-contrast CSF-flow interleaved with cortical BOLD to measure glymphatic function via BOLD-CSF coupling
Authors: Eiling Ingmar , Roefs Emiel , de Bresser Jeroen , van Osch Matthias , Hirschler Lydiane
Published: November 2024

Motivation: CSF-mediated brain waste clearance is implicated in proteinopathies such as Alzheimer’s disease. A better understanding of clearance mechanics is needed to understand pathological processes. Goal(s): To quantify flow- and pulsatility dynamics of CSF-motion in the 4th-ventricle using real-time phase contrast (rtPC) with interleaved BOLD-imaging while manipulating flow. Approach: rtPC is first interleaved with inflow-sensitized EPI to prove the same CSF-fluctuations are captured. Then, we show BOLD-CSF coupling between rtPC and cortical BOLD as well as between inflow-EPI and cortical BOLD during breathing and visual-stimulation paradigms. Results: rtPC improves characterization of CSF-flow in the 4th-ventricle compared to traditional BOLD-sequences, showing more coherent BOLD-CSF coupling. Impact: Clinical MR studies are increasingly looking at changes in BOLD-CSF coupling in patient populations as a measure of brain clearance efficiency. By interleaving phase contrast acquisitions with BOLD, we quantify CSF flow dynamics and obtain more robust BOLD-CSF measurements.
Fast 3D-EPI for characterization of CSF motion during the cardiac cycle.
Authors: Goa Pål Erik , Blömer Simon , Stirnberg Rüdiger , Stöcker Tony
Published: November 2024

Motivation: Individual variation in CSF dynamics may affect the efficiency of waste clearance from the brain. Goal(s): To develop a fast and sensitive MRI method for measurement of CSF motion during the cardiac cycle. Approach: Whole brain 3D-EPI at 3mm resolution and volTR=187ms was acquired at 7T for 94 seconds and retrospectively sorted into 20 cardiac phases based on pulse oximeter. Results: CSF dynamics was observed in all ventricles as well as in sub-arachnoid space, in addition to arterial pulsation. Both magnitude and phase pulsations were present in the 3 subjects acquired. Highest sensitivity to motion was observed along the phase-encoding direction. Impact: We show that fast 3D-EPI at 7T is very sensitive to the motion of CSF during the cardiac cycle. This method may be used to characterize CSF dynamics on individual patient level and aid understanding of brain diseases.
Applying adaptive convolution to brain data – Making use of transfer learning
Authors: Graf Simon , Wohlgemuth Walter , Deistung Andreas
Published: November 2024

Motivation: Deep learning approaches for QSM-based dipole inversion lack generalizability towards acquisition parameters. Goal(s): Our aim was to address data scarcity by integrating known information in the network model and investigate the feasibility of transfer learning. Approach: The acquisition parameters (voxel size, FOV orientation) were integrated with manifold learning. The models were pre-trained on large-scale synthetic data sets and fine-tuned on in-vivo brain data in a second step. Results: The use of manifold learning increased generalizability, while transfer learning substantially improved the quality of computed susceptibility maps. Impact: While this study demonstrates the feasibility of cross-domain knowledge transfer in deep learning approaches for QSM, it also points to the potential of fine-tuning network parameters to scanner-specific data in general, boosting the performance of neural networks therewith.
Travelling wave MRI with a parallel-plate waveguide loaded with a metamaterial at 7 T
Authors: Solis-Najera Sergio , Lazovic Jelena , Rivera Saul , Vazquez Fabian , Rodriguez Alfredo
Published: November 2024

Motivation: The utilization of traveling-wave MRI in conjunction with a parallel-plate waveguide provides an alternative for acquiring images at ultrahigh magnetic fields, circumventing the resonant frequency limitations. Goal(s): To improve the image quality and to investigate the application of metamaterials within the waveguide to improve performance. Approach: A bio-inspired surface coil in the transceiver mode and a C-shaped unit metamaterial made from copper sheets laminated onto a nonconductive board within the parallel-plate waveguide filled with a saline solution were used. Results: Images acquired with the metamaterial-loaded waveguide demonstrated improved signal-to-noise ratio and closely matched the image quality achieved with in-house birdcage coilsImpact: To provide an effective alternative for remote detection in MRI, enabling high-quality image acquisition with efficiency.
Simultaneous MRI and Ultrasound Imaging on a High-performance Gradient Platform
Authors: Ajala Afis , Mills David , Fiveland Eric , Chan Heather , Lee Seung-Kyun , Foo Thomas , Xu Jia , Bednarz Bryan , Hernando Diego , Wells Shane , Holmes James , Yeo Desmond
Published: November 2024

Motivation: Simultaneous ultrasound (U/S) and MR imaging has been reported on whole-body MRI systems with conventional gradients (CVG) but remains unexplored on high-performance gradient (HPG) platforms. Goal(s): We assessed the MR and U/S image quality, alongside thermal impact on an MR-compatible U/S probe at CVG and HPG configurations. Approach: Fast spoiled gradient echo imaging, echo planar imaging (EPI), B0-field map and U/S probe temperature were measured. Results: Moderate-to-severe susceptibility-induced signal loss (due to U/S probe) extended ~8 mm into phantom at gradient isocenter with no visible U/S image artifacts. A substantial temperature rise was observed on U/S probe during EPI at HPG configuration. Impact: This study evaluates and compares image quality and thermal risks of simultaneous MR and U/S imaging on a high-performance gradient system versus a conventional clinical system. Our findings can help optimize the protocols for image-guided U/S intervention using high-performance gradients.
Helmet RF Applicator Enhances Thermal Magnetic Resonance Theranostics of Brain Tumours
Authors: Rahimi Faezeh , Nurzed Bilguun , Eigentler Thomas , Kuehne Andre , Oberacker Eva , Ghadjar Pirus , Millward Jason , Schuhmann Rolf , Niendorf Thoralf
Published: November 2024

Motivation: Thermal MR adds an interventional dimension to an MRI device. Ultrahigh-field MRI is an excellent fit for ThermalMR since it benefits from multi-channel transmission in the short wavelength regimeGoal(s): This work investigates the MRI and RF heating performance gain of a multi-channel Tx in a helmet array versus an annular array. Approach: We aim to enhance B1+ uniformity for brain MRI at 7.0T and enhance SAR10g for brain thermal therapy using perpendicular RF elements. Results: Our simulations and phantom experiments demonstrate superior mean B1+ coverage and better B1+ uniformity for MRI and enhanced SAR10g for thermal therapy using the helmet configuration. Impact: Dome-shaped helmet transmit RF applicators provide a viable alternative for theranostics involving ultrahigh-field MRI and targeted RF-heating for thermal therapy The performance gain of the helmet transmit RF applicator is demonstrated in numerical simulations and in experiments at 7.0 T.
Brain connectomic and transcriptional signatures of suicidal thoughts and behaviors in major depressive disorder
Authors: Qin Kun , Li Huiru , Hu Rui , Zhang Lisha , Kong Cunqing , Chen Wen , Gong Qiyong , Jia Zhiyun
Published: November 2024

Motivation: Suicide-related connectomic signatures in depression and underlying transcriptional patterns have been poorly understood, most previous findings were limited by small-sample and single-site design. Goal(s): To identify robust brain structural network deficits associated with suicidal thoughts and behaviors (STB) in major depressive disorder (MDD) and to determine related transcriptional profiles. Approach: Based on mutlicenter MRI data of over 700 individuals, group-level connectomic comparisons and connectome-transcriptome association were analyzed. Results: Robust structural connectomic alterations associated with STB in MDD were distributed in the prefrontal, limbic and temporal areas. STB-related connectomic alterations were spatially correlated with genes enriched for cellular metabolism and synaptic signaling. Impact: These findings reveal a robust pattern of brain structural deficits at network level and demonstrate its linkage to gene expression patterns, which provides novel insights into the neurobiological underpinnings and potential markers for prediction and prevention of STB.
Field-Correcting GRAPPA (FCG) for improved mitigation of even-odd and field-related artifacts in EPI
Authors: Wang Nan , Abraham Daniel , Kerr Adam , Wu Hua , Liao Congyu , Cao Xiaozhi , Polimeni Jonathan , Huber Renzo , Setsompop Kawin
Published: November 2024

Motivation: Field perturbation from gradient error and eddy current has been a long-standing issue for EPI, especially with high gradient performance or ramp samplingGoal(s): To develop a MLP based Field-Correcting GRAPPA (FCG) that accounts for spatial-varying field and produces artifacts-mitigated imagesApproach: Calibration data with dual polarity were acquired. A MLP based kernel was trained to take single-polarity data as input and output the clean averaged data. It was applied for both phantom and in vivo undersampled EPI with ramp-sampling. Results: FCG produced best correction results for ramp-sampling EPI, with potentials for wide applications including fMRI. Impact: A Field-Correcting GRAPPA (FCG) technique was developed to correct the field perturbation induced image artifacts for EPI, which accounts for spatial varying field and produced promising resulting on ramp-sampling cases, with great potentials for wide applications including fMRI.
Iso-1.25mm Whole-cerebrum pCASL at 7T for Mapping Depth-dependent Cortical Gray Matter and Tract-specific White Matter Cerebral Blood Flow
Authors: Zhao Chenyang , Guo Fanhua , Shou Qinyang , Shao Xingfeng , Li Yuan , Huang Shuo , Shi Yonggang , Wang Danny
Published: November 2024

Motivation: Mapping CBF in the whole cerebrum extent at a microvascular level at 7T has been hampered by SNR, susceptibility artifacts, BOLD effect, and field inhomogeneity. Goal(s): We aim to achieve an isotropic 1.25 whole cerebrum pCASL imaging. Approach: We developed a pCASL sequence which incorporates recent optimizations of labeling and background suppression and a 3D TFL readout. Poisson-disc undersampling and compressed sensing were used to improve image quality. Results: CBF mapping with high SNR and resolution was achieved, revealing depth-dependent CBF and an inverse relationship between tract-specific CBF and fractional anisotropy. Impact: The proposed pCASL imaging technique will impact neuroscientists by enabling fine-grained mapping of CBF at microvascular level in cortical gray matter and white matter at 7T.
Validation and assessment of venous transit time in the human brain using VICTR MRI
Authors: Shi Wen , Jiang Dengrong , Hu Zhiyi , Hazel Kaisha , Pottanat George , Jones Ebony , Xu Cuimei , Yedavalli Vivek , Lin Doris , Yasar Sevil , Ge Yulin , Moghekar Abhay , Lu Hanzhang
Published: November 2024

Motivation: Venous transit time (VTT) is insufficiently investigated and can be a useful marker for clinical populations with abnormalities in the cerebral venous system. Goal(s): To further verify a novel non-contrast VICTR MRI and investigate advanced VTT properties and their age effects in the brain. Approach: We compared the VTT from VICTR and a contrast-based method. Statistical properties of VTT distribution were studied in a caffeine challenge and compared between young and older subjects. Results: VTT from VICTR MRI showed great agreement with contrast-based VTT. The mean, peak, and spread of VTT increased in the caffeine challenge. VTT is longer in the older subjects. Impact: VICTR MRI can measure venous transit time in the adult brain which increases with age. The non-contrast measurement of venous transit time paves the way for several research avenues to better understand vascular function in the normal and pathological brain.
Patient-specific targeting of VIM using THOMAS segmentation predicts post-MRgFUS side effects: a retrospective evaluation
Authors: Oshima Sonoko , Kim Asher , Sun Xiaonan Richard , Rifi Ziad , Cross Katy A. , Fu Katherine A. , Ellingson Benjamin M. , Salamon Noriko , Bari Ausaf A. , Yao Jingwen
Published: November 2024

Motivation: Precise and personalized targeting for MR-guided focused ultrasound (MRgFUS) is desired to ensure treatment efficacy and avoid side effect. Goal(s): To assess THalamus Optimized Multi Atlas Segmentation (THOMAS) on white-matter nulled MRI for targeting of the ventral intermediate (VIM) thalamic nucleus in MRgFUS for tremor patients. Approach: We retrospectively assessed the relationships of standard indirectly targeted coordinates, post-FUS lesions, and THOMAS segmentation with post-FUS side effects and tremor scores in patients who underwent VIM-MRgFUS. Results: In patients who exhibited side effects, FUS lesions had a smaller overlap with THOMAS-based VIM segmentation and were located more inferiorly. Impact: THOMAS is a novel automated thalamic segmentation tool which may aide in the targeting of the VIM nucleus, potentially reducing side effects and improving treatment outcomes in MRgFUS for patients with tremor.
Chemical Exchange Saturation Transfer-Based Functional Magnetic Resonance Imaging (CEST-fMRI) in the Human Brain at 3T
Authors: Lu Qicheng , Zhang Yi
Published: November 2024

Motivation: Conventional fMRI techniques indirectly map neural activity through the BOLD effect, but there is a need for a methodology to directly detect dynamic changes in neurotransmitter levels. Goal(s): Our goal was to detect the increase in glutamate concentration in the human brain during a visual task based on CEST. Approach: We performed two tailored experiments on a 3T scanner and used a 4-regressor general linear model (GLM) analysis to extract the metabolite effects from CEST-fMRI signals. Results: A ~0.12% metabolite effect was detected at glutamate-proximal frequency offsets, consistent with our simulation under a 3% increase in glutamate concentrations during brain activity. Impact: Our study successfully revealed the mechanism behind CEST-fMRI and demonstrated its ability to detect dynamic changes in glutamate concentrations during visual stimulation. The CEST-fMRI methodology enables the investigation of neurotransmitter changes, potentially becoming an imaging modality that guides neuroscience research.
Quantification of extravascular lung water using a dual contrast extracellular volume approach
Authors: Seemann Felicia , Halaby Rim , Jaimes Andrea , Wang Haiyan , O'Brien Kendall , Kellman Petre , Herzka Daniel , Lederman Robert , Campbell-Washburn Adrienne
Published: November 2024

Motivation: Extravascular lung water is a feature in heart failure. Current lung water MRI methods cannot distinguish between intravascular and extravascular fluid, and therefore cannot fully isolate the pathology. Goal(s): To isolate and quantify extravascular lung water by developing a dual-contrast extracellular volume (ECV) method, leveraging different extracellular compartmentalization of gadolinium and ferumoxytol. Approach: We calculated ECVextravascular=ECVgadolinium-ECVferumoxytol from lung T1-maps with native, gadolinium and ferumoxytol contrast. Validation was performed in porcine models of increased extravascular and intravascular lung water. Results: As expected, ECVextravascular differed between baseline and the extravascular intervention (27±4.1% vs 32±1.6%, p=0.005), but not for the intravascular model (22±4.7% vs 22±4.4%, p=0.91). Impact: Dual contrast extracellular volume measurements, leveraging the different compartment uptakes of gadolinium and ferumoxytol contrasts, is a promising method for extravascular lung water quantification, and may enable mechanistic studies of lung water accumulation in patients with dyspnea.
Estimating microstructural parameters from gradient-echo and spin-echo data: a test of the strong collision approximation
Authors: Storey Pippa , Novikov Dmitry
Published: November 2024

Motivation: To develop noninvasive methods to interrogate magnetic microstructure. Goal(s): To test whether the strong collision approximation can accurately characterize microstructure of known geometry and magnetic susceptibility from gradient-echo and spin-echo signals. Approach: Experimental data were acquired from phantoms containing polystyrene microbeads of 10$$$\mu$$$m, 20$$$\mu$$$m and 40$$$\mu$$$m diameter suspended in gadolinium-doped gelatin. Data were fitted using a published model based on the strong collision approximation and a lookup table prepared from Monte Carlo simulations. Results: The strong collision approximation overestimated bead size and underestimated magnetic susceptibility from gradient-echo data. For spin-echo data, it yielded poor estimates of susceptibility and was insensitive to bead size. Impact: The strong collision approximation is a non-perturbative approach for predicting gradient-echo and spin-echo signals in the presence of magnetic microstructure. It employs the Krogh construction and a simplified diffusion propagator. We show how those simplifications affect estimates of microstructural parameters.
Lifespan Iron Accumulation in Dopaminergic Neurons Studied by Quantitative MRI and X-ray Fluorescence
Authors: Büttner Felix , Reinert Tilo , Jäger Carsten , Brammerloh Malte , Morawski Markus , Lipp Ilona , Falkenberg Gerald , Brückner Dennis , Bazin Pierre-Louis , Crockford Catherine , Wittig Roman , Kirilina Evgeniya , Weiskopf Nik
Published: November 2024

Motivation: Dopaminergic neurons require iron for their function but suffer from iron overload in age. Goal(s): To non-invasively monitor the age-related iron accumulation in dopaminergic neurons, we investigated mechanisms of iron-induced MR contrast in the substantia nigra across the lifespan. Approach: We combined quantitative MRI, X-ray fluorescence imaging and biophysical modelling in a unique animal model: ethically collected postmortem chimpanzee brains. Results: The iron load of dopaminergic neurons and the effective transverse relaxation rates in the substantia nigra increased with age. The biophysical model accurately links the relaxation rate to the iron load and neuronal density, which demonstrated its suitability for ages above puberty. Impact: Monitoring cell-specific iron concentrations of dopaminergic neurons and neuronal densities in the substantia nigra throughout the lifespan holds potential of an early neuroimaging biomarker for Parkinson’s disease.
Derivation of a suitable exchange fraction expression to model diffusion-driven exchange with MR measurements.
Authors: Ordinola Alfredo , Özarslan Evren , Yin Yu , Bai Ruiliang , Herberthson Magnus
Published: November 2024

Motivation: Transmembrane water exchange in brain tissue is a process often modelled via the first order kinetics reaction (1OKR) expression. However, this expression does not account for diffusion dynamics, suggesting it is not suitable to describe diffusion-driven exchange. Goal(s): Assess the difference between the 1OKR expression and the exchange fraction derived from a generally defined system. Approach: The exchange fraction was derived considering geometry, and compartment-specific relaxation processes of a system via the diffusion-reaction equation. Results: The derived exchange fraction features a multi-exponential recovery at short times and a mono-exponential decay at long times, both of which are not captured by the 1OKR expression. Impact: The two additional features of the exchange fraction found in this work provide additional insight on a system’s microstructure and properties. This expression can therefore be the basis of new biophysical models which more accurately describe the water exchange process.
Modular Dynamic Torso Motion Phantom for MRI
Authors: Tamm Ernesto Gomez , Hodul Andreas , Ornter Markus , Chalampalakis Zacharias , Nguyen Quang , Soanca Onisim , Janicaud Vivian , Laistler Elmar , Rausch Ivo , Frass-Kriegl Roberta
Published: November 2024

Motivation: The development of motion tracking and correction methods requires suitable motion phantoms. Goal(s): The design, fabrication, assembly and testing of a modular dynamic torso phantom. Approach: The phantom consists of a saline-filled acrylic shell, with dimensions comparable to a human torso and three distinct interior motion modules. Two linear piezo stages are used to mimic breathing motion of the chest wall and the abdominal organs including the heart, respectively. A pneumatic system is used to move a heart mock-up to represent cardiac motion. Results: The motion capabilities and MR compatibility of the phantom are validated in 3 T MRI experiments. Impact: This work presents the development of a dynamic torso phantom for MR applications, i.e. a scientific instrument that can serve as ground truth for the investigation and characterization of novel motion compensation and tracking methods.
Simultaneous EEG-fMRI at 7T with adapted EEG leads and reference sensors for high-quality, high-resolution imaging: human evaluation
Authors: Martinez Cristina Sainz , Wirsich Jonathan , Vulliémoz Serge , Lemay Mathieu , Bastiaansen Jessica , Wiest Roland , Jorge João
Published: November 2024

Motivation: The combination of BOLD-fMRI at 7T with EEG could bring novel insights to neuroscience. However, the combination has remained challenging due to accentuated artifacts and RF-coil constraints. Goal(s): To implement a first-of-its-kind 7T EEG-fMRI framework combining key developments from recent studies, and assess its safety, data quality and functional sensitivity in humans. Approach: Extensive tests in phantom and humans(N=8) including field mapping, structural MRI and fMRI (1.6 and 0.8mm-resolution) acquired with+without EEG. Comparisons of data quality and functional sensitivity. Results: The framework proved safe and feasible with fMRI down to sub-mm resolution, with moderate quality losses and potentially negligible impact on functional sensitivity. Impact: This study characterizes the feasibility of 7T-EEG-fMRI with high sensitivity and acceleration capabilities, which could bring valuable insights to research in e.g. laminar functional connectivity, or localization of epileptogenic sources and their propagation pathways, for clinical diagnostic and pre-surgical planning.
Hippocampal amide proton transfer value is associated with the imaging marker and total burden of cerebral small vessel disease
Authors: Mu Ronghua , Qin Xiaoyan , Zheng Wei , Yang Peng , Huang Bingqin , Deng Kan , Shen Zhiwei , Zhu Xiqi
Published: November 2024

Motivation: Exploring the CSVD imaging markers can provide insights into the pathophysiology of CSVD, which is crucial for understanding its etiology, development, and clinical interventions. Goal(s): To investigate potential variations in hippocampal APT values among individuals with CSVD imaging markers and varying degrees of CSVD total burden. Approach: All the participants conducted the cognitive assessment and the MRI scans. And statistical analysis was used for evaluation. Results: The hippocampal APT values among different CSVD total load groups were significantly different (p<0.001). The mediation models demonstrated that the APT values of the hippocampus partially mediated the association between CSVD total load and MoCA score. Impact: Hippocampal APT values may serve as a biomarker for the early detection of neurodegeneration in CSVD patients.
Non-invasive segmentation of individual watershed areas allows detection of hemodynamic impairments in internal carotid artery stenosis
Authors: Hoffmann Gabriel , Preibisch Christine , Richter Franziska , van Osch Matthias , Václavů Lena , Kufer Jan , Bodden Jannis , Kallmayer Michael , Göttler Jens , Zimmer Claus , Kaczmarz Stephan , Schmitzer Lena
Published: November 2024

Motivation: Internal carotid artery stenosis (ICAS) accounts for ≈10% of strokes. Individual watershed areas (iWSA) are especially susceptible to hemodynamic impairments. Currently, iWSA are segmented from contrast agent-based time-to-peak (TTP), limiting applicability. Goal(s): We aimed towards non-invasive iWSA segmentation based on arterial transit time (ATT) from Hadamard-encoded pseudo-continuous ASL. Approach: Overlap of iWSA from ATT and TTP was investigated and agreement of extracted hemodynamic parameter values such as cerebrovascular reactivity (CVR) was evaluated and ICAS-induced parameter-lateralization was investigated. Results: ATT-based and TTP-based iWSAs overlapped well, with excellent agreement in quantitative parameters and significant lateralization of hemodynamic parameters in ICAS within both iWSA delineation approaches. Impact: We successfully segmented iWSA from non-invasive ATT and demonstrated sensitivity to ICAS-related impairments, in agreement with TTP-based iWSA segmentation. ATT-based iWSAs facilitate longitudinal investigation without contrast application in cerebrovascular diseases such as ICAS or Moyamoya.
Two-axon population (TAP) modelling for large axon diffusion imaging in the peripheral nervous system
Authors: Grussu Francesco , Boonsuth Ratthaporn , Battiston Marco , Wheeler-Kingshott Claudia Gandini , Yiannakas Marios
Published: November 2024

Motivation: The stick (zero-radius cylinder), a standard diffusion MRI model for the intra-axonal brain white matter signal, may not be suitable in the peripheral nervous system (PNS), due to co-existence of small and large axons. Goal(s): To test the feasibility of replacing the stick model with a two-axon population (TAP) approach, accounting for large axons, in the PNS. Approach: We compared TAP versus standard stick modelling in simulations, and derived TAP metrics in the sciatic nerve in vivo. Results: TAP enables more accurate parameter fitting than stick modelling, and is shown to be feasible in vivo in healthy controls and multiple sclerosis patients. Impact: We propose two-axon population (TAP) diffusion-weighted MRI, a method tailored for imaging of the peripheral nervous system, characterised by co-existence of small and large axons. TAP may enable more accurate microstructural imaging than standard approaches, providing non-invasive markers of neurophysiology.
Simultaneous self-supervised reconstruction and denoising for low SNR, sub-sampled training data with Robust SSDU
Authors: Millard Charles , Chiew Mark
Published: November 2024

Motivation: For low SNR training data, such as from low-field scanners, sub-sampled images reconstructed via deep learning can be susceptible to errors due to measurement noise. Goal(s): To evaluate the performance of the proposed Robust Self-Supervised Learning via Data Undersampling (Robust SSDU), which removes corruptions due to aliasing and measurement noise in an entirely self-supervised manner. Approach: On the fastMRI dataset and low-field dataset M4Raw, Robust SSDU was compared with a number of benchmarks including supervised training. Results: Robust SSDU exhibited a substantially higher fidelity image restoration than standard SSDU and sharper reconstructions than competing methods that remove measurement noise. Impact: This study demonstrates that high quality image reconstruction with deep learning is achievable when only sub-sampled, low SNR data is available for training. The proposed method could particularly impact the diagnostic potential of images acquired from low field scanners.
Intracranial aneurysm wall enhancement predicts aneurysm growth and rupture: a large-scale multi-center longitudinal study
Authors: Zhu Chengcheng , Liu Qingyuan , Mossa-basha Mahmud , Levitt Michael , Wang Shuo
Published: November 2024

Motivation: Unruptured intracranial aneurysm (UIA) with wall enhancement identified on vessel wall MRI was considered at high risk of rupture and growth. But previous longitudinal studies were limited by small sample size (n<130). Goal(s): To evaluate whether wall enhancement can predict UIA growth or rupture in a large-scale multi-center longitudinal study. Approach: 709 UIA patients were followed by 2 years. Growth or rupture was recorded as primary outcome. Results: Size ratio, aspect ratio, irregular shape and wall enhancement index were identified as factors of UIA instability. The final model has an AUC of 0.89, which was superior to traditional risk models (AUC 0.67-0.70, p<0.001). Impact: To our best knowledge, this is the largest longitudinal study using vessel wall MRI to predict the natural risk of UIA rupture and growth. The model can potentially help select small but high-risk UIAs for early intervention.
Association of duration of dialysis and myocardial damage in end-stage renal disease patients: assessed by cardiovascular magnetic resonance
Authors: Wang Zhiyue , Guo Haodong , Liu Fei , Wang Xiaoping , Li Haige , Liu Weiyin
Published: November 2024

Motivation: Explore relationship between cardiac image and duration of dialysis. Goal(s): To evaluate myocardial damage using CMR in end-stage renal disease (ESRD) patients undergoing hemodialysis and further explore its relationship with duration of dialysis. Approach: Patients with long- and short-term dialysis were included. CMR parameters (native T1 value and ECV) and two biochemical results (brain pro-natriuretic peptide and troponin T) were compared. Results: Native T1 value, ECV, brain pro-natriuretic peptide and troponin T were significant different in two groups. Multiple linear regression analysis showed that native T1 value and ECV were independently associated with duration of dialysis and troponin T. Impact: Quantification of myocardial fibrosis in ESRD is challenging. CMR imaging is useful in the detection of cardiac damage. Longer durations of dialysis may lead to poor outcomes. Our purpose was to explore relationship between cardiac image and duration of dialysis.
Intraoral Coax-based Dipole Antenna for Improved Dental Magnetic Resonance Imaging
Authors: Hayat Shahzeb , Shah Izaz , Yoo Hyoungsuk
Published: November 2024

Motivation: In this work, we investigated the performance of a coaxial dipole antenna compared with a single wire for dental MRI at 3 T. Goal(s): A fully flexible coaxial dipole antenna was designed and optimized with an aim to improve the signal-to-noise ratio, image quality, and sensitivity while maintaining safety performances. Approach: Based on electromagnetic simulations and MRI results it is demonstrated that in single conductor has a current distribution, which is strongly inhomogeneous leading to inhomogeneous B1+ field distribution. Results: In contrast, coaxial cable with multiple gaps offers homogenous current distribution yielded to optimum B1+ field distribution. Impact: The development of a fully flexible coaxial intraoral antenna with lightweight, capable of overcoming impedance and homogeneity challenges, has the potential to revolutionize dental MRI. Enhanced patient comfort and adaptability improve image quality, advancing dental MRI's utility in medical imaging.
Calibration-Free pTx of the Cervical, Thoracic, and Lumbar Spinal Cord at 7T
Authors: Aigner Christoph , Alarcon Manuel Sánchez , D'Astous Alexandre , Alonso-Ortiz Eva , Cohen-Adad Julien , Schmitter Sebastian
Published: November 2024

Motivation: Addressing the issue of lengthy parallel transmit (pTx) adjustment times caused by the absence of a dedicated spinal cord (SC) coil setting, which limits SC imaging at ultra-high field. Goal(s): Enhance imaging efficiency by universal shim modes that can be applied without the need for additional adjustment time for different SC regions and coils. Approach: We have built a library of channel-wise B1+ maps and optimized universal RF shims to optimize transmit homogeneity and efficiency. Results: The proposed universal shims significantly improve B1+ efficiency, achieving a 50% enhancement compared to the default shim mode, while eliminating the need for subject-specific pTx adjustments. Impact: The development of universal shims not only enhances SC imaging efficiency at ultra-high field but also streamlines the process by eliminating lengthy subject-specific pTx adjustments, expecting SC imaging to become more usable for non-pTx experts.
A size-adaptive RF coil with integrated NMR field probes for pediatric brain Imaging at 7 T
Authors: Yazdanbakhsh Pedram , Sprang Christian , Couch Marcus , Feizollah Sajjad , Tardif Christine , Rudko David
Published: November 2024

Motivation: To develop a safe, size-adaptive RF head coil with an integrated commercial field monitoring system for pediatric imaging at 7T MRI. Goal(s): Performance of the size-adaptive RF head coil was quantitatively evaluated and compared to that of a commercial receive adult head coil (Nova Medical). Approach: The coil performance was evaluated at the largest and smallest dimensions of the receive former, with and without integrated field probes. Results: Simulations of transmit coil demonstrated that the coil is safe for pediatric imaging of subjects below 30 kg at 7T. The SNR performance of the coil was comparable to the commercial coil. Impact: The eight channel dipole transmit and 32 channel size-adaptive receive array with integrated 16 NMR commercial field monitoring probes for imaging pediatric (4-9 years old) brain at 7T enables safe and high-quality imaging of subjects below 30 kg at 7T.
Inexpensive Easy-To-Use Commercial MRI Readable Thermometer
Authors: Russek Stephen , Keenan Kathryn , Stupic Karl , Stoffer Cassandra , Wilkes Teryn , Brittain Jean , Rutkowski David , Kammerman Jeff , Kim Jeehun , Li Xiaojuan
Published: November 2024

Motivation: To demonstrate the utility of inexpensive easy-to-use commercial MRI-readable thermometers for monitoring phantom temperatures during imaging and enable temperature corrections in an MSK relaxometry phantom developed for inter-site relaxation time (T1, T2, T1ρ) comparisons. Goal(s): Provide convenient thermometry for temperature corrections for phantom based intersite comparisons of relaxation time and diffusion measurements. Approach: Commercial incubator thermometers with a temperature range of 15°C to 50°C were characterized for phantom thermometry. Results: Commercial incubator thermometers demonstrated to be MRI readable with an accuracy of ±0.2°C using standard imaging protocols, as long as the thermometer axis is perpendicular to the readout direction. Impact: Easy to use MRI-readable thermometry is available to enable temperature corrections to minimize confounding factors in inter-site comparisons.
A contact-free signal and power transfer system.
Authors: Wang Bili , Lakshmanan Karthik , Rehner Robert , Bollenbeck Jan , Wang Jianmin , Brown Ryan
Published: November 2024

Motivation: Wireless MRI signal transfer reduces the need for physical cabling that can complicate patient table design and impede local coil preparation. Proposed techniques to eliminate cabling can involve complex subsystems for clock synchronization, high-fidelity ADC, low EMI, and high-speed data transfer. Goal(s): Our goal was to implement a short distance contact-free signal and power transfer system without complex circuitry. Approach: We designed a system to eliminate coil-to-scanner connections by transferring coil signals and preamplifier power over short distances using inductively coupled loops. Results: SNR in images acquired with the contact-free and traditional (wired) systems were within 3-5%. Impact: The proposed contact-free signal and power transfer system eliminated the physical connection between the coil and scanner while maintaining SNR, which opens the door to wireless coils and more robust and low-cost, detachable patient tables.