bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of Time-to-Total Knee Replacement Surgery with Deep Learning using MRI and Clinical Data
Authors: Cigdem Ozkan , Hedayati Eisa , Rajamohan Haresh R. , Cho Kyunghyun , Chang Gregory , Kijowski Richard , Deniz Cem M.
Published: November 2024

Motivation: The combination of deep learning, MRI, and clinical data for predicting the time to total knee replacement surgery in knee osteoarthritis patients has been investigated. Goal(s): The 3D Resnet18 model was employed to extract features from MRI scans, and relevant clinical variables were integrated to establish a comprehensive predictive model. Approach: Time-to-surgery probabilities were estimated using the ensemble random survival forest model. The model’s performance was evaluated across clinical variables, two MRI sequences, and their combinations. Results: The proposed approach aims to help the precision of TKR surgery decision-making using artificial intelligence. Impact: This study fuses deep learning, survival analysis, MRI, and clinical data to accurately predict time-to-TKR surgery. Our approach has the potential to enhance TKR surgery decision precision.
Test-Retest analysis of atTRACTive with a dissimilarity uncertainty sampling scheme on the Corpus Callosum of mice
Authors: Peretzke Robin , Bohn Jonas , Kirchhoff Yannick , Roy Saikat , Schroers Julian , Kurz Felix , Lenga Pavlina , Becker Daniela , Brandt Geva , Hirjak Dusan , Maier-Hein Klaus , Neher Peter
Published: November 2024

Motivation: Accurate tractography-based segmentation of white matter tracts is crucial for tasks such as pre-surgical planning. Fully automated methods are limited to predefined tracts and struggle with anatomical deviations, e.g. caused by tumors. Goal(s): Our goal is to enhance the manual segmentation process through a novel and intuitive approach. Approach: We recently developed atTRACTive, a tool for semi-automatic fiber dissection relying on entropy-based active learning. In this work, we have improved atTRACTive and conducted an initial evaluation of its test-retest reliability in comparison to traditional ROI-based tract segmentation methods. Results: atTRACTive has demonstrated superior test-retest reliability compared to traditional ROI-based segmentation approaches. Impact: The method offers guidance to researchers in the intuitive and efficient segmentation of arbitrary white matter tracts. Instead of drawing challenging-to-reproduce ROIs, users can simply annotate meaningful streamlines, which are then used to train a classifier.
MOdel-free Diffusion-wEighted MRI (MODEM) with Machine Learning for Accurate Tissue Characterization
Authors: Dan Guangyu , Feng Cui , Zhong Zheng , Sun Kaibao , Karaman Muge , Hu Daoyu , Li Zhen , Zhou Xiaohong Joe
Published: November 2024

Motivation: Mathematical, biophysical, and/or statistical models are typically used to analyze diffusion-weighted imaging signals, yielding quantitative biomarkers. Those model-based approaches, however, often suffer from limited model capability, fitting instability, and degeneracy. Goal(s): To use a MOdel-free Diffusion-wEighted MRI technique (MODEM) to differentiate underlying tissues based on diffusion signal intensities. Approach: We developed a machine-learning-based approach which we call MOdel-free Diffusion-wEighted MRI technique(MODEM) and assess its performance by using synthetic DWI data from Monte Carlo simulations and cervical staging dataset. Results: MODEM exhibited superior diagnostic performance to the model-based approach in both Monte Carlo simulations and cervical cancer staging data. Impact: A model-free machine-learning-based approach provides superior performance to the conventional diffusion-model-based approach for differentiating the underlying tissue properties.
Automated image prescription for liver MRE using an AI method trained without manual labeling
Authors: Fullerton Garrett , Buelo Collin , Rettmann Dan , Guidon Arnaud , Reeder Scott , Hernando Diego , Starekova Jitka
Published: November 2024

Motivation: MRE is a reliable, quantitative method for the assessment and staging of liver fibrosis. The standard manual MRE image prescription requires proper placement over the liver to ensure consistent MRE quantification. Scan positioning is relatively time-consuming and prone to error and inconsistency.Goal(s): To develop and implement an automated methodology for MRE prescription from localizers, trained entirely from technologist-prescribed clinical exams. Approach: Extracted MRE scan coordinates from 354 clinical exams and trained a YOLOv8-nano object detection network to predict prescription planes from a multi-plane localizer series. Results: We successfully developed a method for automated MRE prescription with implementation on a clinical MRI system. Impact: Automatic image plan prescription for MRE can minimize technologist-dependent planning errors and scan inconsistency. This may lead to subsequent improvements in both the value and reproducibility of MRE as a quantitative biomarker of liver fibrosis.
Automated Detection of Suboptimal Fat Suppression - A Simulation Study
Authors: Vasanawala Sauram , Syed Ali , Pauly John
Published: November 2024

Motivation: Fat suppression on MR images is not always completely successful. Identification of inadequate fat suppression can be difficult for technologists while they are multitasking. Unidentified low quality images inhibit radiologists’ ability to diagnose. Goal(s): This work develops an automatic method to detect inadequate fat suppression in extremity MRI exams. Approach: Two-point Dixon fat-water image pairs were combined to simulate varying degrees of fat suppression failure and serve as training data for a CNN. Results: Greater than 85% accuracy was obtained on simulated data, which motivates future effort on prospective validation study. Impact: This work may lead to on-scanner software that auto-identifies inadequate fat suppression, prompting repeat scans with more refined shimming or alternative fat suppression methods. This may improve image quality.
Evaluating the performance of deep learning system for detecting focal liver lesions on contrast-enhanced MRI
Authors: Dai Haoran , Xiao Yuyao , Fu Caixia , Grimm Robert , Busch Heinrich , Stieltjes Bram , Choi Moon , Yang Chun , Zeng Mengsu
Published: November 2024

Motivation: The number of focal liver lesions (FLLs) detected by imaging has increased worldwide, highlighting the need to develop a robust, objective system for automatically detecting FLLs. Goal(s): This study aimed to evaluate the application value of deep learning based artificial intelligence (AI) software in detecting FLLs. Approach: We compared the performance and agreement of deep learning based AI software with those of radiologists in detecting and evaluating malignant lesions in enhanced MRI of patients with FLLs. Results: AI displayed effective detection performance for malignant lesions down to <10 mm. The measured size of malignant tumors was consistent with the pathologic and manual sizes. Impact: Our results indicated that the use of AI might promote the detection ability of sub-centimeter-sized liver malignant lesions, providing a reference for selecting clinical treatment schemes.
A maximum a posteriori method for quantitative $$$T_1$$$ mapping with uncertainty using MP2RAGE
Authors: Saunders Adam , Schilling Kurt , O'Grady Kristin , Smith Seth , Landman Bennett
Published: November 2024

Motivation: The MP2RAGE sequence allows for quantitative MRI imaging of $$$T_1$$$ in the brain, but current methods do not provide a way to measure uncertainty in this mapping. Goal(s): We introduce a probabilistic signal representation to allow for $$$T_1$$$ mapping with uncertainty maps. Approach: Using a Monte Carlo simulation, we generate a probability distribution for the MP2RAGE images that allows us to map the posterior distribution of $$$T_1$$$ and generate a measure of uncertainty. Results: Our $$$T_1$$$ map numerically agrees with previous single-echo MP2RAGE methods with limited data while providing a way to map statistical measures like expected value or standard deviation. Impact: Our posterior distribution allows for uncertainty quantification in $$$T_1$$$ mapping with MP2RAGE, and it opens up the possibility for other probabilistic methods. The proposed method allows for a better quantitative understanding with only a minor modification to the acquisition sequence.
Multi-contrast quantitative mapping with an unsupervised reconstruction method based on implicit neural representation
Authors: Lao Guoyan , Feng Ruimin , Wei Hongjiang
Published: November 2024

Motivation: Multi-contrast quantitative MRI usually requires multiple scans, leading to long acquisition time and potential inter-scan misalignment. Goal(s): To achieve the multi-contrast quantitative MRI acquisition in a single scan and improve the accuracy of the quantitative mapping. Approach: We developed a multi-contrast quantitative mapping sequence to simultaneously obtain T1, T2, T2* maps and subvoxel QSM. Reconstruction was conducted to directly estimate the underlying quantitative maps from the highly undersampled high-dimensional k-space data. The proposed framework was validated on the simulation, phantom and healthy volunteers. Results: The results demonstrated that our proposed method exhibited a high correlation with references on the quantitative maps. Impact: The proposed acquisition and reconstruction framework can simultaneously provide multi-contrast quantitative maps of the whole brain within a 5.8-minute scan. This new technique is clinically promising for tissue characterization and pathological research in neurosciences.
Rapid T2 mapping with blip-reversed multi-echo planar imaging
Authors: Utkur Mustafa , Timms Liam , Wang Zhe , Wallace Tess , Kurugol Sila , Afacan Onur
Published: November 2024

Motivation: Current methods for T2 mapping are time-consuming and susceptible to motion artifacts, hindering their clinical utility. Goal(s): Our goal is to develop a rapid and motion-robust T2 mapping technique. By significantly reducing scan times and eliminating motion artifacts, we aim to enhance the clinical feasibility of quantitative T2 mapping across diverse patient populations. Approach: Standard spin-echo EPI sequence was modified by incorporating additional readouts with alternating phase-encoding directions. Geometric distortions due to susceptibility-induced effects were corrected using TOPUP tool. Results: T2 maps generated using our sequence showed good correspondence with the T2 map from 3D GRASE reference both in phantom and volunteer studies. Impact: Our single-shot T2 mapping technique based on multi-echo spin echo EPI sequence not only advances imaging speed and accuracy but also caters to uncooperative populations, including pediatric patients and individuals prone to movement.
Quick, Quiet and Quantitative Magnetization Transfer Imaging
Authors: Pinna Oliver , Wood Tobias , Barker Gareth
Published: November 2024

Motivation: Quantitative magnetization transfer (qMT) imaging has been long known to provide valuable information for MS imaging. To promote the widespread adoption of this technique faster and efficient scan protocols are needed. Goal(s): To develop a patient-friendly, rapid, and reliable quantitative magnetization transfer scan. Approach: Our sequence consists of an inversion pulse followed by a zero-echo time (ZTE) readout. We observe magnetization transfer (MT) exchange effects between a fully inverted free water pool and a partially inverted bound water pool. Results: We show the feasibility of the method by producing quantitative maps of MT parameters. Impact: Fast patient-friendly quantitative scans will enable informative and frequent monitoring of MS. This is useful for personalised management of therapeutic courses and for drug development. We demonstrate a quick, quiet quantitative MT scan targeted to multiple sclerosis.
In vivo application of MP-PCA denoising of quantitative T2* and magnetic susceptibility maps (QSM) in normal and pathological cerebral tissues
Authors: Doniza Liad , Fuchs Patrick , Karsa Anita , Lee Mitchel , Blumenfeld-Katzir Tamar , Radunsky Dvir , Shmueli Karin , Ben-Eliezer Noam
Published: November 2024

Motivation: Higher spatial resolution can increase the diagnosis quality of Quantitative Susceptibility Mapping (QSM) by improving the sensitivity to local field variations and minimizing partial volume effects, yet, at the cost of reduced signal-to-noise ratio (SNR). Goal(s): Improve the SNR of high-resolution QSM data, while preserving structural properties of the tissue. Approach: Use Marchenko-Pastur principal component analysis (MP-PCA) to denoise T­2*-weighted images, and generate quantitative T2* and QSM maps with higher SNR. Results: MP-PCA denoising was able to efficiently improve the SNR on numerical phantom and in vivo. Proof of concept is provided for healthy brain anatomy and for a patient with brain metastases. Impact: Marchenko Pastur principal component analysis can be used to enhance the SNR of T2*-weighted images, T2* maps, and QSM maps while preserving the fine details of the tissue.
Differentiation between high-grade gliomas and solitary brain metastases: a comparison of five diffusion weighted MRI models
Authors: He Libing , Chen Meining , Yi Yinqiao , Yan Xu , Zhang Qin , Xu Xiaoxue
Published: November 2024

Motivation: Differentiating high-grade gliomas (HGGs) from solitary brain metastases (SBMs) using conventional MRI remains challenging due to similar imaging features. Goal(s): Evaluating the diagnostic performance of advanced diffusion models, like NODDI and MAP, against traditional techniques like DWI, DTI and DKI in distinguishing HGGs from SBMs. Approach: Using a 12-minute sequence, parameters of NODDI, MAP, DKI, DTI, and DWI were reconstructed using specialized postprocessing tools. Results: NODDI_Viso was the most effective parameter in distinguishing HGGs from SBMs, and combining parameters of DTI_AD, DTI_RD, MAP_MSD and NODDI_Viso further enhanced classification accuracy. Impact: Combined models from DTI, MAP and NODDI shows promise as sensitive imaging biomarkers for neuro-oncology and potentially improves treatment strategies for HGGs and SBMs.
Pixel-wise correlation among DCE/DSC metrics in brain tumor with Multitasking-based dynamic imaging for cerebrovascular evaluation (MT-DICE)
Authors: Xiao Jiayu , Chen Yang , Wu Jushen , Ye Jason , Chow Frances , Zada Gabriel , Shiroishi Mark , Cen Steven , Fan Zhaoyang
Published: November 2024

Motivation: DCE and DSC-derived Ktrans, ve, CBV, and kio are measures of microcirculatory function, perfusion, and water channel in brain tumors. They have shown clinical values in tumor grading, treatment response, and prognosis evaluation. However, their pixel-wise inter-correlation remains unclear, partially due to separate scans in conventional protocol or having one of them omitted. Goal(s): To investigate the pixel-wise correlation of Ktrans, ve, CBV, and kio in patients with brain tumors using MT-DICE. Approach: The multiparametric maps simultaneously quantified by MT-DICE were analyzed pixel-by-pixel within the slice showing the largest enhancing tumor. Results: Ktrans and ve correlate well with kio in the spatial distribution. Impact: MR multitasking-based dynamic imaging for cerebrovascular evaluation (MT-DICE) provides spatial quantitative maps of BBB permeability, tumor perfusion, and water channel. The information helps better understand intra-tumor heterogeneity and may assist in selecting biopsy sites and precisely monitoring treatment response.
Orientation Dispersion Index identifies sub-areas in the edema tissue of glioblastoma
Authors: Debiasi Giulia , Salvalaggio Alessandro , Colpo Maria , Cecchin Diego , Corbetta Maurizio , Bertoldo Alessandra
Published: November 2024

Motivation: Edema tissue in glioblastoma is not included in surgical resection, even though tumor cells infiltration could be mediated by it. Goal(s): The aim of the study is to investigate the heterogeneity of edema. Approach: Clustering analysis within edema is performed on the orientation dispersion index derived from diffusion magnetic resonance imaging. Then, a non-parametric statistical test is carried out to assess the difference between the resulting edema sub-tissues (e.g., clusters). Results: Two spatially separated clusters are found for all subjects. Statistically significant differences are observed between each couple of resulting clusters. Impact: Edema is not a healthy tissue and the possibility of identifying sub-tissues within it could aid clinical practice and pre-surgical planning. This study works at single-subject level, allowing the focus on the specific glioblastoma cases.
Comparison of Tracer Kinetic Models for Differentiating Glioblastoma and Primary Central Nervous System Lymphoma
Authors: Zhou Jianan , Hou Zujun , Zhu Zhengyang , Tian Chuanshuai , Zhang Bing , Zhang Xin
Published: November 2024

Motivation: The overlapping radiographical features between glioblastoma and primary central nervous system lymphoma (PCNSL) make it difficult to distinguish the two clinically. Goal(s): This study aimed to compare values of conventional and advanced tracer kinetic models based on dynamic contrast enhanced (DCE)-MRI in differentiating glioblastoma and lymphoma. Approach: Patients diagnosed as glioblastoma or lymphoma were examined using dynamic contrast-enhanced MRI. Imaging data were analyzed using tracer kinetic models. Results: Permeability parameters of DP model attained best performance in differential diagnosis, with dominant features comprising significantly higher PS and E in the tumor region of lymphoma than in that of glioblastoma. Impact: Distributed parameter (DP) model demonstrated excellent performance in differentiating PCNSL and glioblastoma and permeability parameters of advanced tracer kinetic models such as PS and E could be promising imaging biomarkers.
Longitudinal brain age is informative of future executive function in Asian children and elderly
Authors: Cheng Susan , Yue Wan Lin , Ng Kwun Kei , Qian Xing , Liu Siwei , Tan Trevor , Nguyen Kim-Ngan , Leong Ruth , Law Evelyn , Gluckman Peter , Chen Christopher , Meaney Michael , Chee Michael , Yeo B.T. Thomas , Zhou Juan Helen
Published: November 2024

Motivation: Brain age models have not been well-tested in non-Caucasian populations or longitudinally. Goal(s): We aimed to determine whether brain age models generalize to an Asian population and whether longitudinal changes in brain age associate with future cognition. Approach: We applied a pretrained brain age model to Singaporean elderly and children, compared our results after finetuning the model, and examined cross-sectional and longitudinal associations with cognition. Results: The model could be directly applied to elderly, but finetuning was necessary for children. The longitudinal change in brain age gap significantly associated with future executive function performance in both elderly and children. Impact: We show that there is real potential for generalizing brain age models to diverse populations, and that the longitudinal change in brain age contains additional information about future executive function, compared to baseline brain age.
Healthy aging in human thalamic nuclei: an evaluation of volumetric atrophy and kurtosis microstructural metrics
Authors: Hübner Sebastian , Novello Lisa , Ianus Andrada , Jovicich Jorge
Published: November 2024

Motivation: Volumetric and microstructural characterization of thalamic nuclei is currently meeting growing interest in neuroimaging. Thalamic nuclei microstructural features, especially, may be used as biomarkers to study changes in both normal aging and degenerative diseases. Goal(s): Quantify age-related differences in volumetry and microstructure of thalamic nucleiApproach: We used 3T structural MRI (volumetry) and Diffusion Kurtosis Imaging (microstructure)Results: Our main result is that thalamic volumetric atrophy effects related to healthy aging are significant and stronger than those given by microstructure estimates. Impact: Macroscopic atrophy is more sensitive to healthy aging differences relative to microstructure effects derived from Diffusion Kurtosis Imaging.
Cognitive impairment is associated with elevated oxygen extraction and metabolism in the medial temporal lobe
Authors: Song Jie , Shi Wen , Hazel Kaisha , Jones Ebony , Pottanat George , Xu Cuimei , Suconic Julia , Lin Doris , Rosenberg Paul , Yasar Sevil , Kalyani Rita , Moghekar Abhay , Albert Marilyn , Lu Hanzhang , Jiang Dengrong
Published: November 2024

Motivation: Currently, the primary MRI-based biomarker for cognitive dysfunction is the atrophy of medial-temporal-lobe (MTL). However, MTL atrophy represents a late stage of tissue damage. Functional biomarkers such as the MTL oxygen metabolism may be more sensitive in early stages. Goal(s): To evaluate the association of MTL oxygen metabolism with cognitive function in non-demented elderly individuals. Approach: We used a novel MRI technique to evaluate the MTL oxygen metabolism in 48 elderly subjects. Cognitive function of the participants was assessed. Results: Worse cognitive scores were associated with elevated oxygen extraction and metabolic rate in the MTL, but not with the volume of MTL. Impact: Our findings indicated that measuring the oxygen extraction and metabolic rate in the medial temporal lobe may be more sensitive than structural atrophy in detecting tissue damage in early stages of cognitive impairment.
Thalamic Subnuclear Volumetry for Early Detection of Alzheimer's Disease in Postmenopausal Women
Authors: Kim Gwang-Won , Park Kwangsung , Kim Yun-Hyeon , Jeong Gwang-Woo
Published: November 2024

Motivation: Women are at a heightened risk of Alzheimer's disease (AD) compared to men. Also, AD and aging are intrinsically interconnected to each other and are mediated by molecular, cellular and biological system. Goal(s): This study aimed to evaluate volume changes of the subcortical regions including the thalamic subnuclei in women with AD vs. postmenopausal women. Approach: Twenty-five thalamic subnuclei were extracted extracted from each hemisphere of the subject's T1 image. Results: Our findings suggest that reduced volume in both the right laterodorsal thalamic nucleus and right hippocampus could represent a key biomarker for predicting early stage of AD in postmenopausal women. Impact: These findings may be helpful for a better understanding of AD pathogenesis and also for providing an objective target for early interventions to prevent AD.
Insights into neurodegeneration in Alzheimer’s disease from regional Aβ aggregation, iron level, and gene expression in postmortem human brain
Authors: Yao Junye , Li Zhenghao , Zhou Zihan , Bao Aimin , Zhong Jianhui , Wei Hongjiang , He Hongjian
Published: November 2024

Motivation: Quantifying Aβ in patients with Alzheimer's disease poses a challenge due to the colocalization of Aβ accumulation and iron deposition. Goal(s): Our goal was to simultaneously quantify Aβ and iron in ex-vivo human brains affected by AD. Approach: We used a novel subvoxel QSM method to measure Aβ and iron levels. The gene transcriptomic profiles were further investigated using PLS and ontological analysis. Results: Regions with higher diamagnetic and paramagnetic susceptibility were found higher levels of gene expression relating to the protein modification process and metal ion binding, as well as a relative abundance of exCA and glutamatergic neurons.Impact: The quantification of diamagnetic and paramagnetic susceptibility via APART-QSM can offer valuable insights into regional-specific vulnerabilities in Alzheimer’s disease, particularly those related to Aβ aggregation and iron accumulation. This can aid clinicians to better find therapeutic targets.
Effect of diagnostic and genetic status on the relationship between rs-fMRI complexity and tau & amyloid PET in Alzheimer’s disease.
Authors: Jann Kay , Cen Steven , Santos Mariella , Wijesinghe Dilmini , Zhang Ru , Ringman John , Wang Danny
Published: November 2024

Motivation: Decreased brain function in Alzheimer’s Disease can be assessed by complexity of resting-state fMRI. Specifically, in precuneus and medial temporal lobe rsfMRI-complexity is reduced in MCI and AD and negatively associated with tau-PET uptake. However, its association with amyloid deposition or effects of genetic characteristics (APOE4) remains unknown. Goal(s): To investigate the association between rsfMRI-complexity, tau-PET and amyloid-PET as well as influence of APOE4 status. Approach: Multivariate linear models assessing rsfMRI-complexity, tau-PET, amyloid-PET and APOE4 in select regions of interest. Results: rsfMRI-complexity shows a strong significant inverse relationship with tau but not amyloid and APOE4 increases this effect. Impact: We show that rsfMRI-complexity shows a strong association with tau but not amyloid deposition and that genetic risk in form of APOE4 strengthens this effect. Thus rsfMRI-complexity adds a novel tool to investigate impaired brain functionality in AD progression.
Eddy current heating of weakly conductive objects in high-performance gradient coils
Authors: Lee Seung-Kyun , Li Ke , Spence Dan
Published: November 2024

Motivation: Conductive objects such as RF shield can pose heating risk due to eddy current in fast-switching gradient fields. Goal(s): To develop a systematic method to calculate eddy current heating when multiple gradient coils pulse simultaneously with independent waveforms. We explicitly consider interaction of different coils. Approach: Our method was tested against experimental measurement of temperature rise in a high-performance head-only gradient coil (MAGNUS) at 3T. Results: Predicted and measured local eddy current heating showed good qualitative agreement. Importance of coil coupling was demonstrated by the experimental data. Impact: We present a systematic method to calculate eddy-current heating induced by multiple independent field coils. The work permits accurate prediction of RF shield heating in high-performance gradient systems to ensure patient safety.
Addressing Gradient Imperfection Related Bias in Stack-of-Stars MRI for Free-Breathing, Confounder-Corrected T1 Mapping
Authors: Muslu Yavuz , Wang James , Cashen Ty , Hernando Diego , McMillan Alan , Reeder Scott
Published: November 2024

Motivation: Non-Cartesian sampling strategies enable free-breathing imaging due to their robustness against motion but are susceptible to artifacts related to gradient imperfections. Such artifacts may manifest as bias or structured noise in quantitative imaging applications. Goal(s): In this study, we explore the effects of gradient imperfections and evaluate the performance of gradient correction methods in non-Cartesian, confounder-corrected T1 mapping using both phantom and in vivo imaging experiments. Approach: For this purpose, we compare confounder-corrected T1 maps reconstructed with data-driven and calibration-based gradient correction approaches. Results: Our initial results indicate that gradient correction methods are essential for mitigating the bias due to gradient imperfections. Impact: This study confirms that gradient imperfections result in bias in non-Cartesian quantitative imaging applications. Our findings indicate that T1 relaxometry is less susceptible to gradient imperfections than PDFF and R2* quantification. The application of gradient correction methods mitigates this bias.
Practical Utilization of Nonlinear Spatial Encoding: Fast Field Mapping and FRONSAC-wave
Authors: Zhang Horace , Constable R. Todd , Galiana Gigi
Published: November 2024

Motivation: Nonlinear gradient imaging is impeded by time-consuming field mapping and the encoding ability is yet to be unleashed. Goal(s): To accelerate nonlinear field mapping and make use of nonlinear encoding. Approach: We report a fast and robust estimation method for nonlinear field mapping and studied the utility of simultaneously applying nonlinear and linear gradients, referred to as FRONSAC-wave, where the high-frequency nonlinear field waveform is complementary to a lower frequency linear field waveform. Results: The fast field mapping decreases the field mapping time from 10 hours to <0.5 hour. FRONSAC-wave demonstrates better imaging ability compared to wave at various acquisition settings. Impact: This study demonstrates the advantage of combined sinusoidal waveforms on linear and nonlinear gradients and proves the feasibility of fast mapping for nonlinear fields. It opens prospects for utilization of nonlinear field encoding in clinical scenarios.
Gradient Preemphasis Predicted by Reinforcement Learning
Authors: Martin Jonathan , Banik Rana , Does Mark , Harkins Kevin
Published: November 2024

Motivation: Gradient hardware chains can exhibit dynamic nonlinearities that cannot be easily corrected with linear models and require more sophisticated approaches. Goal(s): Our goal was to develop a flexible and dynamic approach to correct nonlinear MRI system imperfections. Approach: We developed a reinforcement learning method for predicting gradient preemphasis and evaluated it in a realistic simulated environment with obscured state information. Results: Reinforcement learning is able to accurately predict gradient preemphasis even when system state information is unknown. Impact: The ability to dynamically correct system imperfections through reinforcement learning may allow the development of more robust imaging systems that can adapt to complex, nonlinear distortions, reducing the need for expensive hardware corrections or inflexible, system-specific system models.
Feasibility of motional eddy current-reduced, passive eddy current shielding of MRI gradient coils
Authors: Lee Seung-Kyun , Hua Yihe
Published: November 2024

Motivation: High-performance gradient coils can induce substantial eddy current in the magnet causing heating and artifacts. Motional eddy current at high B0 exacerbates the problem. Goal(s): To investigate the feasibility of patterned, additional passive shielding to reduce both electromagnetically-indued and motional eddy currents. Approach: A proof-of-concept experiment was conducted in flat geometry, where shielding efficiency at 3T was compared between a solid copper and a patterned copper plate that mimicked the eddy current image of a driving coil. Results: The leakage field of patterned copper agreed with theory and was more localized in frequency and space. The shielding efficiency was improved at high frequencies. Impact: We demonstrated that vibration-induced motional eddy current of a passive conductive shield can be dramatically altered by eddy current cut-outs. The results can be used to build a compact, high-field scanners with reduced magnet-gradient interaction.
B0 Eddy Current Compensation of an Unshielded Pulsed Z2 Gradient for Applications in Human Brain Proton MRSI
Authors: Kumaragamage Chathura , Nixon Terry , McIntyre Scott , De Feyter Henk , de Graaf Robin
Published: November 2024

Motivation: ECLIPSE1 is a novel method to achieve robust outer volume suppression (OVS) in 1H-MRSI of the human brain. To-date ECLIPSE has been performed with an unshielded-Z2 coil that led to significant B0-eddy currents, necessitating the use of pre/post gradient pulses2,3 for MEGA-edited MRSI acquisitions. Goal(s): An inner volume selection (IVS) based ECLIPSE approach would provide B1 and T1 independent lipid suppression, however editing efficiency is compromised due to B0-eddy currents. Approach: A home-built 64-channel gradient controller4 was extended with B0-compensation capabilities to drive a Z0-shim coil. Results: B0-eddy currents were attenuated by 200-fold following B0-compensation, and allows robust MEGA-edited ECLIPSE-IVS based MRSI acquisitions. Impact: Constructing a shielded-Z2 coil for ECLIPSE is complex compared to an unshielded coil. A simpler approach is to construct an unshielded-Z2 with B0 compensation and gradient pre-emphasis, provided that eddy currents induced by switching an unshielded-Z2 gradient can be well-characterized.
Enhanced parallel imaging with pseudo-linear magnetic fields using multi-channel matrix gradient coil
Authors: Qu Shuxian , Gao Yang , Huang Yiman , Shang Haifang , Wang Haifeng , Zhang Xiaotong
Published: November 2024

Motivation: Nonlinear magnetic fields have been used as an effective alternative to linear counterparts to offer improved spatial encoding efficiency. Goal(s): Nonlinear encoding methods often encounter center imaging blurring and require additional information for non-bijective encoding fields to differentiate mis-localized intensities. Approach: We propose to use pseudo-linear spatial encoding magnetic fields to address these challenges and enhance encoding efficiency. Based on that, two encoding strategies were proposed. Results: Center resolution discrepancy could be mitigated according to numerical simulations and preliminary experiments. Impact: The mitigation of the center blurring presents a reference for future research employing nonlinear gradient encoding.
Shear-induced Sodium Dynamics within Red Blood Cells membrane using advanced 23Na Single and Triple Quantum Filtered Rheo-NMR methods.
Authors: Pavlovskaya Galina , McBride Mark , Khan Raheela , Selby Nick , Meersmann Thomas
Published: November 2024

Motivation: Increased blood viscosity has been reported in red blood cell senescence and pathologies of decreased perfusion such as chronic kidney disease. Goal(s): Rheological NMR is a powerful, although still underutilized, tool to assess the molecular-mechanical links in flowing media. This study's primary objective was to explore the dynamic alterations in Na+ interaction with glycocalyx of red blood cells exposed to the physiological shear forces experienced within the microvasculature in health and disease.Approach: 23Na multiple quantum filtered (MQF) rheo-NMR in RBCs suspensions at varied haematocrit. Results: 23Na MQF rheo-NMR are efficient to detect Na+ interaction with glycocalyx of red blood cells under deformationImpact: Potential sodium “rheo-markers” reflective of blood viscosity in health and disease are proposed.
Physiological and macropathological results in swine model at 123 MHz in experimental setup for investigating thresholds of tissue damage
Authors: Cho Chie-Hee , Lüdemann Lutz
Published: November 2024

Motivation: Radiofrequency used during MRI exams heat tissue. The temperature increase is unknown and the thermoregulatory responses still need to be analyzed. Goal(s): To analyse the temperatures within the thresholds. Are any changes seen. Is the biological simulation replicable in living swine. Approach: SAR levels in the 2.mode were planned in the swine as an animal model. Results: The thermoregulatory model (temperature going into a plateau) is only one pattern next to 3 other patterns (linear, parabolic, and sinusoidal). So these will change the calculations of simulations for temperatures in humans receiving MRI exams. Impact: Radiofrequency induced temperature changes in MRI exams need to be reevaluated as new thermoregulatory patterns are observed. Increased internal temperatures are subconsciously discerned causing thermoregulation to avoid tissue damage.
PET/MRI dual-model Granzyme B targeted probe for non-invasive early diagnosis of acute heart allograft rejection
Authors: Wei Zhuxin , Zhao Shihua
Published: November 2024

Motivation: Early diagnosis of transplant rejection can help to improve the immune-related management of transplant recipients. Goal(s): Developing the new methods for early and non-invasive diagnosis of acute cellular rejection to unmet clinical needs. Approach: Develop a PET/MRI dual-model granzyme B (GzmB) targeted probe for non-invasively detection of transplant acute cellular rejection. Results: In preclinical heart graft models of rejection, our PET/MRI dual-model GzmB targeted probe allow noninvasive discrimination of early acute cellular rejection mediated by recipient cytotoxic CD8+ T cells. Impact: In the future, this technology developed a PET/MRI dual-model probe for imaging GzmB produced by cytotoxic CD8+ T cells, enabling early non-invasive diagnosis of allograft rejection with high sensitivity and high spatial resolution.
Echo-planar spectroscopic imaging with flyback readout: ghost peaks and micro-imaging
Authors: Weis Jan , Babos Magor , Estrada Sergio , Selvaraju Ram
Published: November 2024

Motivation: To assess echo-planar spectroscopic imaging (EPSI) with flyback readout gradients in preclinical MR system. Goal(s): To demonstrate spectral ghost artifacts produced by two, three, and four interleaved gradient echo trains and to measure water, fat, and water-fat shift artifacts free images. Approach: Flyback EPSI with two, three, and four interleaved gradient echo trains. Results: The proposed approach with four interleaved gradient echo trains and with four echoes in each train enables high spectral bandwidth in combination with narrow receiver bandwidth and a very good water/fat signals separation. It improves SNR without the undesired consequence of water-fat shift artifacts. Impact: Echo-planar spectroscopic imaging with flyback readout enables measurement of water, fat, and water-fat shift artifact-free images. Four interleaved echo trains with four echoes in each train provide high spectral, and narrow receiver bandwidth, and a very good water-fat separation.
Perfluorocarbon-PLGA particle ultrastructure affects pH sensitivity in 19F NMR and MRI
Authors: Mali Alvja , White Paul , Stumpe Nicolas , van Riessen Koen , Cadiou Cyril , Chuburu Françoise , Srinivas Mangala
Published: November 2024

Motivation: We aim to advance biocompatible 19F-MR contrast agent to enhance imaging diagnostic in cancer. Goal(s): Nanoparticles (NPs) internal structure impacting Gd-enhanced effect on 19F-MR signal strength, relaxation times and pH-sensitivity. Approach: Systematic investigation using 1H/19F-MR to understand how NPs structure affects the interaction between co-encapsulated Gd and 19F and focusing on multi-core NPs and their acidic pH-sensitivity on 19F-MR relaxation times. Results: Our study revealed that 19F-MR signal strength is pH-dependant. After cellular uptake, multi-core NPs co-encapsulating Gd and PFCE exhibited higher T2 values and stronger signal, influenced by lysosomal acidity, highlighting pH role in MR signal modulation. Impact: The pH-sensitive 19F-MR probe enhance NPs tracking after cell internalization and by that it holds great promise for tissue pathology imaging, as cancer diagnostics.
Exploring enhanced abscopal effect: Molecular imaging insights into tumor physiologic changes in combined radiation and PD-1 blockade therapy
Authors: Yamashita Kota , Kishimoto Shun , Horie Kazumasa , Yamamoto Kazutoshi , Brender Jeffery , Devasahayam Nallanthamby , Merkle Hellmut , Krishna Murali
Published: November 2024

Motivation: Radiation therapy (RT) for primary tumors triggers regression in non-irradiated metastatic lesions via the abscopal effect, can potentiate the effects of immune-checkpoint blockade on the non-treated tumors in the same animal. Goal(s): To examine physiological alterations of the treated tumor linked to the abscopal effect. Approach: We used MRI-based imaging techniques, such as EPR oximetry, DCE MRI, and 13C DNP MRI. Results: After RT and PD-1 blockade, we observed improved oxygenation, permeability, perfusion, and CD8+ T cell infiltration in metastatic (untreated) tumors. Interestingly, primary tumor with increased permeability and perfusion and reduced hypoxic fraction (HF10) before treatment correlated with augmented abscopal effect post-treatment. Impact: Metastatic tumor conditions improved with RT and ICB, enhancing oxygenation, permeability, perfusion, and CD8+ T cell infiltration. Primary tumor's elevated permeability and lower HF10 correlated with higher AE in metastatic tumors, confirmed through carbogen-enhanced perfusion.
the application value of automatic extraction of intratumoral susceptibility signal intensities in abdominal tumors
Authors: An Qi , Ma ChangJun , Zhuang MingRui , Liu Ailian , Liu Ailian
Published: November 2024

Motivation: By studying the application of ITSS ratio values measured under different threshold conditions, we hope to be able to quickly identify and predict abdominal tumors preoperatively. Goal(s): To explore the application value of automatic extraction of ITSS in abdominal tumors. Approach: Friedman The rank sum test was used to compare the differences of ITSS measurements under different threshold conditions. Results: Under different threshold conditions, the ITSS ratios of uterine sarcoma, ovarian cystadenocarcinoma, hepatic vascular carcinoma and prostate cancer were respectively higher than those of degenerative uterine fibroids, ovarian cystadenomas, hepatic hemangioma and prostate hyperplasia. Impact: The automatic extraction of ITSS can effectively, quickly and subjectively predict the differential diagnosis of abdominal tumors under different threshold conditions, which has a good clinical application prospect.
Prognostic Performance of LI-RADS v2018 Features and Clinical-Pathological Factors in Alpha-Fetoprotein-Negative Hepatocellular Carcinoma
Authors: Wang Leyao , Wang Sicong , Ma Xiaohong , Zhao Xinming
Published: November 2024

Motivation: Evaluate the performance of the LI-RADS v2018 features and clinical-pathological factors for predicting the prognosis of AFP-negative HCC. Goal(s): To evaluate the performance of the LI-RADS v2018 features and clinical-pathological factors for predicting the prognosis of AFP-negative HCC. Approach: A total of 169 AFP-negative HCC patients were enrolled. Risk factors associated with prognosis were identified by Cox regression analysis. Results: Six risk factors, namely the LI-RADS category, blood products in mass, MVI, tumor size, cirrhosis, and ALBI grade, were associated with recurrence-free survival. The model effectively stratified patients with AFP-negative HCC into high- and low-risk groups with significantly different outcomes (p < 0.05). Impact: In this study, our prognostic model composed of the LI-RADS category, blood products in mass, MVI, tumor size, cirrhosis, and ALBI grade accurately classified patients into different recurrence risk groups.
Differentiation between inflammatory myofibroblastic tumor and colorectal liver metastasis on gadoxetic acid-enhanced MRI
Authors: Li Jinkui , Lei Junqiang , Zhu Yi
Published: November 2024

Motivation: Inflammatory myofibroblastic tumors (IMT) of the liver can mimic malignant tumors, yet, they lack definitive radiological characteristics. Goal(s): To identify gadoxetate acid-enhanced MRI (Gd-EOB-MRI) features distinguishing hepatic inflammatory myofibroblastic tumor (IMT) from colorectal liver metastasis (CLM). Approach: This retrospective study included 10 IMT (0.7-7.1 cm) and 28 CLM (0.4-5.4 cm) patients who underwent Gd-EOB-MRI. Two reviewers assessed tumor characteristics. Results: Peripheral hypointense rim on T1WI, and arterial phase and/or portal venous phase, corresponding to the delayed enhanced rim on transitional phase, layered appearance on T2WI, and obscure hypointensity on hepatobiliary phase were commonly in IMTs, but rare in CLMs. Impact: The distinctive imaging features on Gd-EOB-DTPA MRI such as early target appearance and delayed enhanced rim and obscure hypointensity on Hepatobiliary phase, are helpful in differential diagnosis of IMT from colorectal liver metastasis.
Elevation of HCC perfusion by diffusion-derived vessel density (DDVD) biomarker: Higher HCC perfusion than earlier IVIM reports.
Authors: Yao Dian-Qi , Li Xin-Ming , Lu Hao-Jun , Chen Wei-Bo , Quan Xian-Yue , Wang Yi-Xiang
Published: November 2024

Motivation: HCCs mostly show higher perfusion values compared with the adjacent normal liver tissue. Paradoxically authors reported a decrease IVIM-PF(perfusion fraction) of HCC relative to adjacent liver. Goal(s): DWI-derived surrogate biomarker DDVD (diffusion-derived vessel density) is a physiological surrogate of the area of micro-vessels per unit tissue area. This study applied DDVD to assess perfusion of HCC. Approach: 72 patients were included. DDVD= (signal intensity at b=0)/ROIarea – (signal intensity at b=2/ROIarea). Results: (tumor DDVD)/(liver DDVD) was 2.942 (median), majority of HCC showing a much higher DDVD than liver. Impact: DDVD overcome the pitfalls associated with IVIM PF.
Assessment of decompensation in patients with cirrhosis based on gadoxetic acid enhanced MR imaging parameters
Authors: liu maotong , zhang Tao , Zhang Xue-Qin , Zhao Xian-ce
Published: November 2024

Motivation: It is important to identify patients with cirrhosis at high risk of decompensation or death using noninvasive methods to stabilize disease progression and reduce patient mortalityGoal(s): To investigate whether the functional parameters from gadoxetic acid–enhanced MRI can predict decompensation in cirrhosis. Approach: To compare MRI parameters and clinical parameters between CACLD and DACLD groups. Associations between MRI parameters and clinical parameters were investigated. To differentiate the diagnostic performance of MRI parameters and clinical parameters between CACLD and DACLD groups. Results: The functional parameters from gadoxetic acid–enhanced MRI can predict decompensation in cirrhosis. Impact: This study confirms that non-invasive imaging parameters can predict the decompensation of cirrhosis and provides a new method for clinicians to evaluate the condition of patients with cirrhosis.
Investigating Respiratory Cycle-Dependent B0 in Liver MRI at 3T
Authors: Strasser Timo , Stelter Jonathan , Spieker Veronika , Weiß Kilian , Braren Rickmar , Schnabel Julia , Karampinos Dimitrios
Published: November 2024

Motivation: Respiratory motion disturbs the stability of the primary magnetic field (B0), leading to potential image artifacts. Despite the significant influence of respiratory motion on B0, understanding these variations in the liver remains understudied in quantitative MRI. Goal(s): To provide a comprehensive analysis of respiration-induced B0 variations in the liver. Approach: The study used direct simulations, acquisition simulations followed by reconstruction, and in vivo scans to quantify B0 variations in the liver. Results: Maximal temporal fieldmap variations were subject dependent and showed a mean variation in the order of 24.9 Hz across the respiratory cycle in the region close to the liver-diaphram interface. Impact: This research provides a clearer understanding of respiratory motion effects on MRI, particularly in the liver. These insights could lead to improved image clarity for quantitative imaging.
Free-breathing simultaneous quantification of fat fraction, R2*, and T1 at 0.55T: Validation in a clinical cohort
Authors: Ohliger Michael , Remick Isabelle , Hong Cheng , Hope Thomas , Chen Jingjia , Sodickson Daniel , Chandarana Hersh , Li Zhitao , Feng Li , Yang Yang
Published: November 2024

Motivation: Improve accessibility of MRI by measuring quantitative liver biomarkers at 0.55T. Goal(s): Perform and validate free-breathing radial stack-of-stars for simultaneous measurement of liver fat fraction, R2*, and T1 on a 0.55T system in patients with chronic liver disease. Approach: 11 subjects undergoing 3T MRI were offered a 0.55T examination. Fat fraction and R2* were compared at both field strengths. Composite T1 was compared to water-only T1. Results: Fat fraction at 0.55T was highly correlated to 3T, with minimal bias and variance. R2* correlation did not achieve statistical significance. Composite T1 was linearly related to water-only T1. Impact: Free-breathing simultaneous measurement of important liver biomarkers is achievable in a low-cost commercially available MRI system, which promises to help make the benefits of MRI more accessible to patients who need it.