bluuebunny/crossref_metadata_2025 huggingface dataset:
Linearity and Bias of Proton Density Fat Fraction Across the Full Dynamic Range (0-100%): a Multiplatform, Multivendor Phantom Study at Two Sites.
Authors: Hu Houchun , Chen Henry , Hernando Diego
Published: November 2024

Motivation: Performance assessment of PDFF in phantoms and in vivo, including linearity and bias, and reproducibility and repeatability, have largely focused between the range of 0-50%. Goal(s): We analyzed PDFF performance in a two-site phantom study across the full 0-100% PDFF range. Approach: We used commercially available quantitative 3D chemical-shift-encoded water-fat MRI pulse sequences across three vendors at 1.5T and 3T. Results: Results demonstrate strong linearity and minimal bias {pooled slope and intercept for 1.5T=0.99 (95% CI: 0.981-0.997), 0.61 (0.17, 1.04); for 3T=1.00 (0.995, 1.005), 0.69 (0.39, 0.97)} of PDFF across 10 MRI systems. Pooled reproducibility coefficient (RDC) across 30 phantom exams was 3.92%. Impact: PDFF across the 0-100% range can be reliably estimated with minimal bias and strong linearity using current commercial offerings from MRI vendors at 1.5T and 3T, with intra-scanner repeatability coefficient<2% (in PDFF%) and inter-scanner, inter-site, and inter-vendor RDC<4% (in PDFF%).
Age dependency of abdominal fat depot volumes and proton density fat fractions in people with obesity
Authors: Wu Mingming , Somasundaram Arun , Rupp Selina , Han Jessie , Junker Daniela , Reik Anna , Naebauer Stella , Raspe Johannes , Patzelt Lisa , Wiechert Meike , Rueckert Daniel , Hauner Hans , Holzapfel Christina , Karampinos Dimitrios
Published: November 2024

Motivation: As cardiometabolic risk in obesity is associated with specific body composition types, we aim at deciphering age-related body composition changes in people with obesity. Goal(s): To assess age-specific abdominal organ volume and proton density fat fraction (PDFF) in people with obesity and predict chronological age. Approach: An nnU-Net-based automatic pipeline was used to segment abdominal organs. Machine-learning-based methods were applied to predict chronological age based on the organs' volumes and PDFF in chemical-shift encoding-based MRI. Results: The best predictors for chronological age were increased visceral adipose tissue volume and elevated ectopic fat deposition in the paraspinal muscle, measured via proton density fat fraction. Impact: Age-specific differences in volumes and PDFF of abdominopelvic fat depots, and ectopic fat in liver and two muscles were found in people with obesity using automated segmentation on quantitative chemical-shift encoding-based MRI scans.
The feasibility of APT and IVIM in renal malignancies: A Preliminary Study
Authors: Liu Xiaofan , Wang Xia , Zhang Sheng , Tian Gang , Yu Chanjuan , Zhao Na , Yue Xiuzheng , Han Yuedong
Published: November 2024

Motivation: Amide proton transfer (APT) imaging studies are gradually expanding to the body, with few applications in renal diseases and a lack of tumor studies. Goal(s): In the present study, we aimed to investigate the ability of APT and voxel-wise intravoxel incoherent motion (IVIM) imaging to detect renal malignancies. Approach: We preliminarily analyzed the ability of APT imaging to discriminate malignant tumors from normal renal tissues, combined with each parameter of IVIM imaging, which has high diagnostic efficacy. Results: The results showed that APT imaging was feasible and superior to IVIM imaging in discriminating renal malignant tumors from normal renal tissues. Impact: APT imaging has potential clinical applications in diagnosing of renal malignancies and provides a reference for subsequent accurate studies of APT imaging of renal tumors.
In-vivo measurement of hepatic lipid composition with J-difference-editing-MRS
Authors: Zhou Yufan , Lin Dingyi , Zhou Jiaqiang , You Shiyang , Cao Yang , Cai Chunli , Hsu Yi-Cheng , Zhao Yuchen , Wang Min
Published: November 2024

Motivation: Hepatic lipid composition is important for diagnosis and prognosis of many hepatic diseases and for studying lipid metabolism. Goal(s): This study aimed to apply J-difference-edited-MRS (JDE-MRS) for better measurement of hepatic lipid composition and evaluated its effectiveness in detecting lipid profile changes among metabolic disorders. Approach: Hepatic lipid composition was measured and compared among healthy, NAFLD and T2DM human subjects using JDE-MRS under 3T, as well as among normal, obese and T2DM rat models using conventional MRS under 7T. Results: The JDE-MRS application in human liver is reliable and the results shows differences between different groups, with similar results in rats. Impact: This study demonstrates the feasibility of applying JDE-MRS in human liver, which can be used to quantify hepatic unsaturated lipid profile and can provide a reliable biomarker for clinical investigations of lipid metabolism in hepatic diseases.
Enhancing Prognosis Prediction for Lung Cancer Patients with Brain Metastasis by Combining Brain MR and Lung CT Radiomic Features
Authors: Chen Jyun-Ru , Lee Cheng-Chia , Yang Huai-Che , Chung Wen-Yuh , Wu Hsiu-Mei , Guo Wan-You , Lu Chia-Feng
Published: November 2024

Motivation: Control of metastatic and primary tumors has been identified as prognostic factors for lung cancer patients with brain metastasis. However, prognosis prediction by combining imaging features of metastatic and primary tumors was less explored. Goal(s): This study investigated the prediction efficacy based on image traits of brain metastasis and primary lung cancer. Approach: The radiomic features separately extracted from brain MRI and chest CT images were merged to build the survival prediction models. Results: The proposed prediction model showed superior performance compared to the models based on a single modality in lung cancer with brain metastasis. Impact: This study suggested that survival prediction can be enhanced by combining features of brain metastasis MRI and lung cancer CT. Imaging characteristics of both primary and secondary (metastatic) tumors are valuable for prognostic prediction in lung cancer with brain metastasis.
Using Multi-sequence MRI-based Convolutional Neural Network to Predict the Methylation Status of MGMT Promoter in Glioma
Authors: Chen Xiaohua , Chen Zhiqiang , Zhang Ruodi , Zhou Yunshu , Liu Shili , Xiong Yuhui
Published: November 2024

Motivation: The MGMT promoter is closely associated with the survival period of glioma patients and their response to chemotherapy drug temozolomide. Predicting the promoter status of MGMT accurately pre-operator is crucial for making personalized treatment decisions for glioma patients. Goal(s): To propose models based on CNNs to predict the MGMT methylation status of gliomas using conventional pre-operative MR images. Approach: Building three CNNs models based on T2WI, T2-FLAIR, CE-T1WI images, respectively. Fusing features to build the fourth model to predict the MGMT methylation status. Results: All models can predict the MGMT status effectively and accurately, the fused-feature model has the best diagnostic performance. Impact: Models based on conventional MRI sequences and VASARI features provide the clinical value for evaluation of molecular typing in gliomas. It is expected to become a practical tool for the non-invasive characterization of gliomas to help the individualized treatment planning.
A deep multimodal fusion framework for MRI-based segmentation of intracranial arterial calcification
Authors: Wang Xin , Canton Gador , Guo Yin , Zhang Kaiyu , Hatsukami Thomas , Zhang Jin , Sun Beibei , Zhao Huilin , Zhou Yan , Mossa-Basha Mahmud , Yuan Chun , Balu Niranjan
Published: November 2024

Motivation: Recently, MRI-based intracranial arterial calcification segmentation has got increasing interest due to its clinical value, but current approaches to this challenging problem suffer from poor performance. Goal(s): To develop a deep learning model for enhancing calcification segmentation on MRI by using CT as additional training resource. Approach: A dissimilarity loss is proposed to align the latent features learned from MRI and CT of the same subject, thus making MR feature simpler and it easier for segmentation. Results: Compared with several commonly used segmentation networks, our model demonstrates superior performance in calcification segmentation. The ablation study further shows the effectiveness of the dissimilarity loss. Impact: The proposed model could be applied in clinical scenarios to automatically segment calcification on cerebral MR scans and it does not require CT imaging. Radiologists could leverage the segmentation result in the analysis of various vessel plaque components.
AtlasSeg: Atlas Prior Guided Dual-UNet for Cortical Segmentation in Fetal Brain MRI
Authors: Xu Haoan , Zheng Tianshu , Xu Xinyi , Shen Yao , Sun Jiwei , Sun Cong , Wang Guangbin , Wu Dan
Published: November 2024

Motivation: Automatic segmentation of fetal brain remains challenging partially due to the dynamically changing anatomical structures during fetal brain development. Goal(s): To enhance segmentation accuracy through incorporating gestational age-specific information as a guidance, we introduce AtlasSeg, a dual-U-shape network with dense attentive interactions. Approach: By providing atlas volume and segmentation label at the corresponding gestational age, AtlasSeg effectively extracts the contextual features of age-specific patterns and structures that assist segmentations. Results: AtlasSeg demonstrated superior performance against six other segmentation networks in both standard and out-of-distribution experiments, in two fetal MRI datasets. Ablation tests further demonstrated the role of atlas guidance. Impact: Through gestational age-specific atlas-guided information, AtlasSeg can serve as an accurate and robust automatic segmentation tool for its superior performance in both in-distribution and out-of-distribution tests, which is useful for quantitative analysis in large-scale fetal brain studies.
Hepatobiliary Phase Synthesis Using Multi-Task Learning GAN: Application to Liver Fibrosis Classification
Authors: Zheng Rencheng , Shi Nannan , Shi Yuxin , Yang Zidong , Xia Xueqin , Chang Hing-Chiu , Chen Weibo , Chu Ying-Hua , Wang Chengyan , Wang He
Published: November 2024

Motivation: Hepatobiliary phase (HBP) has important clinical diagnostic value for liver diseases, but its long acquisition time can pose issues with scanning resources and patient cooperation. Goal(s): Our goal was to design a generative model for HBP synthesis based on early phases in hepatobiliary-specific contrast-enhanced MRI. Approach: We proposed a multi-task learning deep learning model and evaluated its performance on a multi-center dataset. Results: The proposed model exhibited superior HBP synthesis performance compared to the classic Pix2Pix model. The synthetic HBP was comparable to the real HBP, and significantly outperformed early phases in subsequent liver fibrosis grading tasks. Impact: The proposed approach has the potential to accurately synthesize HBP, which is expected to be extended to clinical practice for rapid acquisition of HBP in hepatobiliary-specific contrast-enhanced MRI, thereby significantly reducing scanning time and alleviating clinical stress.
Laminar specific fMRI response is mainly regulated by first synaptic input-driven or more synchronous activity
Authors: Jung Won Beom , Im Geun Ho , Jiang Haiyan , Kim Seong-Gi
Published: November 2024

Motivation: While responses to feedforward inputs have been well-observed in layer-specific fMRI studies, our understanding of responses to feedback projections within the ongoing functional processing remains limited. Goal(s): Our study aimed to investigate how synaptic onset and strength contribute to specificity of laminar fMRI responses. Approach: We performed the ultrahigh resolution CBV-weighted laminar fMRI by modulating thalamocortical and corticocortical projections with stimulus onset asynchrony in mice. Results: We observed that the laminar response is highly sensitive to the strength of synaptic inputs, shifting from early to later input sites with increased strength. Impact: Laminar CBV responses are highly regulated by micro-vessels coupled with earlier synaptic input activity, but potentially driven by the most synchronous activity within neural circuits.
Distinct laminar neurovascular and metabolism responses across eccentricity revealed by multi-contrast visual fMRI at 7T
Authors: Shao Xingfeng , Guo Fanhua , Kim Jung Hwan , Ress David , Zhao Chenyang , Shou Qinyang , Jann Kay , Wang Danny
Published: November 2024

Motivation: To better understand the complex interplay between neurovascular responses and metabolism. Goal(s): The goal was to develop a multi-contrast laminar fMRI tool to concurrently measure CBF, CBV, BOLD, and CMRO2 signals. Approach: We employed a novel pulse sequence to simultaneously acquire ASL CBF, VASO CBV, and T2-BOLD signals at a high spatial resolution of 7T. We also incorporated a calibrated fMRI approach (Davis model) to calculate CMRO2, using parameters estimated from breath-hold induced hypercapnia. Results: We found distinct neurovascular and metabolic responses across cortical layers and eccentricities in response to a ring-shaped visual stimulus. Impact: Multi-contrast laminar fMRI significantly impacts neuroscientific research by providing a more comprehensive understanding of neurovascular (CBF, CBV, BOLD) and metabolic (CMRO2) interactions across cortical layers. It opens doors for exploring complex brain functions and disorders.
Creatine CH2 and PCr dynamics closely correlate in dynamic interleaved MRS of exercising muscle
Authors: Klepochova Radka , Niess Fabian , Trattnig Siegfried , Kautzky-Willer Alexandra , Krššák Martin , Meyerspeer Martin
Published: November 2024

Motivation: To explore quantification of skeletal muscle oxidative metabolism by 1H MRS. Goal(s): We used the increased accuracy of 7T MRS with a dedicated RF-coil, interleaved acquisition and localization of 31P information to compare Creatine-CH2 and Phosphocreatine time courses during exercise and recovery. Approach: Eight volunteers were measured on a 7T MR system with RF-coil and ergometer dedicated for exercise. 1H and 31P MR spectra were acquired interleaved during exercise and recovery. Results: Exercise led to disappearance of the Creatine-CH2 resonance, while the CH3 resonance remained stable during exercise. The recovery time constants were similar (τPCr=37±9s and τCr=34±6s) and positively correlated. Impact: The time course of the Creatine-CH2 resonance in skeletal muscle can be accessed via dynamic 1H MRS. If accurately reflecting oxidative metabolism, this technique has the potential to render non-invasive metabolic studies broadly accessible, without needing multi-nuclear MRI capabilities.
Muscle-specific fat fractions during childhood development in typically developing children and children with cerebral palsy
Authors: Bolsterlee Bart , Chow Brian , Rae Caroline , Davies Suzanne , Morgan Catherine , Ball Iain , Lancaster Ann , Rizzo Rodrigo , Rizzo Claudia , Kyriagis Maria , Novak Iona , Herbert Robert
Published: November 2024

Motivation: Little is known about the fat content of the skeletal muscles of typically developing children or children with cerebral palsy. Goal(s): To describe and compare muscle-specific intramuscular fat fractions in typically developing children and children with cerebral palsy. Approach: Proton density fat fractions were calculated for 11 lower leg muscles using mDixon MRI scans of 280 children (5 to 15 years), including 79 with cerebral palsy. Results: Age and sex did not affect mean fat fractions in typically developing children. Fat fractions varied across muscles. Fat fractions were larger, more variable, and increased with age in children with cerebral palsy. Impact: The comprehensive dataset and automation measurement techniques for measurement of muscle-specific fat fractions in typically developing children and children with cerebral palsy may be used to monitor muscle-specific disease progression or measure the effect of interventions.
Potassium (39K) & Sodium (23Na) MRI of dystrophic skeletal muscle tissue at 7T: impact of fatty infiltration on measured tissue ion concentrations
Authors: Gast Lena , Gerhalter Teresa , Türk Matthias , Sapli Alper , Heiss Rafael , Mathy Claudius , Baudin Pierre-Yves , Marty Benjamin , Uder Michael , Nagel Armin
Published: November 2024

Motivation: Combined 23Na/39K MRI at 7T can highlight ion disturbances related to patho-physiological processes within dystrophic muscle tissue. However, quantification of the apparent tissue potassium concentration (aTPC) using 39K MRI is challenging due to low signal-to-noise and rapid signal decay. Goal(s): Here, we investigated the feasibility of quantitative 39K MRI in dystrophic muscle tissue. Approach: The lower leg of 14 FSHD patients and 11 healthy controls was examined using 39K/23Na and 1H MRI at 7T. Results: We found a strongly reduced aTPC in fat infiltrated muscles. After correction for reduced potassium concentration in fat, aTPC values in dystrophic muscles were similar to healthy muscles. Impact: Potassium concentration in fatty tissue is strongly reduced compared to healthy skeletal muscle tissue. This has to be considered when investigating and interpreting aTPC values measured with 39K MRI in fat-replaced skeletal muscle tissue.
A Magnetic Vector Potential-Based Linear Predictor to Increase Peripheral Nerve Stimulation Thresholds in Gradient Coil Design
Authors: Kang Liyi , Xia Ling , Liu Qian , Zhang Qinwei , Yuan Jianmin , Wu Dan
Published: November 2024

Motivation: The linear predictor incorporating a coupled electromagnetic-neurodynamic model shows reliable estimation of Peripheral Nerve Stimulation (PNS) thresholds, which is important for gradient coil design. However, the computational complexity and long computation time within the coupled model leads to difficulties in application. Goal(s): We proposed a simplified predictor based on the spatial distribution of magnetic fields, circumventing complexity of the coupled model. Approach: The magnetic vector potential was employed to form a simplified predictor, serving as a constraint for PNS-optimized gradient coil design. Results: With the simplified predictor, the optimized coil achieved an 84% increase in PNS threshold at a 10% inductance penalty. Impact: Based on the magnetic vector potential, the proposed predictor enabled the simplified evaluation of PNS thresholds through magnetic field spatial distribution. In addition, the proposed method facilitated PNS optimization in gradient coil design.
Design, construction and first experimental results of the high performance LH7 insertable head gradient set at 10.5T
Authors: Rutt Brian , Bratch Alexander , Alejski Andrew , Wade Trevor , Bester Matthew , Ertan Koray , Roemer Peter , Auerbach Edward , Adriany Gregor , Ugurbil Kamil
Published: November 2024

Motivation: Increased gradient performance can address several of technical and physics challenges of UHF MRI. Goal(s): To develop a head gradient coil (known as LH7) for insertion into the body gradient coil of a 10.5T MRI system. Approach: Design innovations include: symmetric folded geometry with variable end-flange angle optimized for shoulder geometry; double Z-primary layer. Results: With 650A, 2000V gradient drivers, the hardware limits of LH7 are Gmax 117mT/m and Smax 900T/m/s. Thermal results demonstrate cooling capacity >45kW. Compared to body gradients, PNS thresholds are 2-3 fold higher. After interfacing LH7 to the CMRR 10.5T, promising experimental characterizations and imaging results have been obtained. Impact: LH7 provides an order-of-magnitude increase in head gradient performance (Gmax*Smax) over body gradients, which, combined with 10.5T B0, should provide major sensitivity and resolution increases for brain mapping by dMRI or fMRI. Experimental results to date are confirming these expectations.
Accelerating MRI with a Wireless Insert Gradient Coil
Authors: Versteeg Edwin , Weersink Rik , Nouwens Sven , Roos Thomas , Siero Jeroen , Klomp Dennis
Published: November 2024

Motivation: High performance gradients enable fast and high-resolution imaging but are costly and cumbersome to install in an existing MRI-systemGoal(s): Present a wireless (resonant) gradient coil setup that yields additional gradient performance without needing a dedicated amplifierApproach: The increased gradient performance was measured using field camera measurements and acceleration performance was assessed retrospectively using phantom experimentsResults: The wireless gradient yielded a factor 23 improvement in slew rate (from 125 T/m/s to 2900 T/m/s) and 28-fold retrospective acceleration resulted in aliasing free images. Impact: A wireless insert gradient coil enables 28-fold accelerated scanning without a supplementary gradient amplifier. This provides a cost-effective pathway for improving gradient performance with minimal system modifications.
Simultaneous Multi-Slice Imaging in DKI and IVIM for Hepatocellular Carcinoma: Correlation with Microvascular Invasion and Histologic Grade
Authors: Wu Yingyi , Ye Zheng , Song Bin
Published: November 2024

Motivation: IVIM and DKI, effective in HCC malignancy prediction, face limitations due to lengthy scan times. The Simultaneous Multi-Slice (SMS) technology has successfully reduced scan times for ADC studies, but its application in IVIM and DKI remains underexplored. Goal(s): To evaluate SMS-accelerated IVIM and DKI's efficacy in predicting HCC microvascular invasion (MVI) and tumor grading compared to conventional methods. Approach: The study enrolled 42 HCC patients, conducting MRI with both conventional and SMS-accelerated DWI, DKI, and IVIM. Results: SMS significantly reduced MRI scan times while maintaining reliable diffusion metrics, proving more effective than ADC in predicting MVI and tumor grades in HCC. Impact: Integrating SMS into IVIM and DKI protocols can notably shorten scan times while preserving diagnostic accuracy in MVI and tumor grading, potentially improving clinical efficiency and patient management.
Low-rank reconstruction for simultaneous Double-Half-Echo 23Na and undersampled 23Na Multi-Quantum Coherences MRI
Authors: Licht Christian , Reichert Simon , Bydder Mark , Zapp Jascha , Corella Shirley , Guye Maxime , Schad Lothar R , Rapacchi Stanislas
Published: November 2024

Motivation: Sodium (23Na) Multi-Quantum Coherences (MQC) MRI potentially provides richer tissue information. However, 3D 23Na multi-quantum coherences imaging lacks conventional 23Na MRI resolution and requires multiple radiofrequency phase-cycling limiting spatial resolution. Goal(s): We propose an efficient sequence to simultaneously acquire Cartesian double-half echo (DHE) 23Na and accelerated 23Na MQC MRI. Approach: Leveraging advanced low-rank matrix completion frameworks to enable simultaneous DHE 23Na and 23Na MQC MRI were tested on numerical simulations, retro- and prospectively undersampled phantom and in vivo brain data acquired at 7T. Results: Simultaneous Cartesian 23Na and higher resolution 3-fold prospectively undersampled 23Na MQC brain MRI of 4 volunteers were obtained. Impact: The new sequence, in combination with the low-rank reconstruction frameworks, enables efficient 23Na and higher resolution 23Na MQC MRI while supporting conventional 1H-based acceleration techniques and offers, therefore, a convenient sequence for the sodium MRI community.
Simultaneous 1H MRF / 23Na MRI in knee cartilage at 7 T
Authors: Adlung Anne , Pursel Zoe , Busi Baptiste , Rodriguez Gonzalo , Madelin Guillaume
Published: November 2024

Motivation: Sodium MRI can provide tissue sodium concentration (TSC) and enable assessment of knee cartilage degradation. Goal(s): We aim to quantify TSC, proton density (PD) and 1H T1 and T2 in the knee from multinuclear simultaneous acquisition. Approach: We acquired 23Na-only FLORET and simultaneous 1H MRF/23Na MRI data in the knee of four healthy volunteers. We calculated TSC maps from both 23Na acquisitions for comparison, and PD, T1 and T2 maps from 1H MRF. Results: Mean TSC in patellar and femorotibial cartilage, and gastrocnemius muscle showed no significant differences between both sodium acquisitions. Mean TSC, PD, T1 and T2 values were within previously-reported range. Impact: We showed that a 3D simultaneous 1H MRF/23Na MRI acquisition at 7 T can provide reliable quantitative maps of TSC, PD, and 1H T1 and T2 relaxation times in cartilage.
Validation of High Spatial Resolution 23Na Imaging of the Skin
Authors: Slater Theodora , Prestwich Ben , Francis Susan
Published: November 2024

Motivation: The storage of sodium in the skin is thought to be a physiologically important regulatory mechanism for blood pressure, volume regulation, and to change with age, hypertension and disease such as renal and cardiovascular disease. Goal(s): To image the skin at higher spatial resolution for improved estimation of skin sodium quantification. Approach: To develop a dual-tuned 23Na/1H skin coil to image a skin ‘phantom’ and the skin in-vivo. To apply a B1-mapping correction and use the skin ‘phantom’ to validate methods, and study the effects of spatial resolution on skin sodium measures. Results: High resolution skin sodium imaging was achieved, improving 23Na quantification. Impact: Improved spatial resolution of sodium imaging measures of the skin will provide improved assessment of quantification of skin sodium to study the effects of age, ethnicity and disease.
3D whole brain mapping of creatine kinase metabolic rate using 31P-MR fingerprinting.
Authors: Widmaier Mark , Kaiser Antonia , Xiao Ying , Huang Zhiwei , Jiang Yun , Lim Song-I , Wenz Daniel , Xin Lijing
Published: November 2024

Motivation: Using 31P MRS combined with magnetization transfer (MT) experiments including saturation transfer or inversion transfer to assess chemical exchange rate of creatine kinase (kCK) in the human brain are time-consuming and limited to 1D-acquisitions. Goal(s): Acquiring a 3D whole brain kCK map. Approach: In this abstract, we introduce an advanced, fast 3D-31P-MRF sequence for the human brain at 7T. Results: The novel 3D-31P-MRF approach is feasible for whole brain mapping of kCK, enabling the investigation of region-specific energy metabolism under various pathological conditions. Impact: Using the novel 3D-31P-MR Fingerprinting approach for whole brain mapping of kCK enables us to investigate region-specific energy metabolism under various pathological conditions and may enhance our understanding of the underlying molecular and metabolic processes.
Fast Volumetric Mapping of Brain NAD Levels Using 7T 31P-MRSI and Learned Probabilistic Subspaces
Authors: Guo Rong , Yang Shaolin , Wiesner Hannes , Li Yudu , Zhao Yibo , Liang Zhi-Pei , Chen Wei , Zhu Xiao-Hong
Published: November 2024

Motivation: Measuring brain intracellular NAD levels has long been of interest, but the current 31P-MRSI methods would take prohibitively long scan times for mapping NAD. Goal(s): To present a method for fast volumetric NAD mapping of the entire human brain. Approach: In vivo 31P-MRSI scans were performed at 7T with a nominal resolution of 1.0 cc within 20 minutes. A probabilistic subspace-based method integrating spectral prior, spatial constraint, and statistical distributions was applied for denoising. Results: The proposed method successfully provided high-resolution brain NAD mapping within 20-minute scans. The results also showed promises in revealing metabolic tissue heterogeneity and age correlation of NAD. Impact: This work demonstrates the feasibility of volumetric brain NAD mapping with a nominal resolution of 1.0 cc within 20 minutes. It may provide a powerful metabolic imaging tool for many applications.
Towards quantifying Gray Matter “micro-connectivity”: the measurable impact of dendritic spines on metabolite diffusion
Authors: Şimşek Kadir , Palombo Marco
Published: November 2024

Motivation: Dendritic spines are fine microstructures increase the complexity of brain cells. Spines are characteristic morphological feature of neurons and their density can change with pathological conditions. Goal(s): Quantification of dendritic spines in gray matter in human brain using diffusion-weighted MR spectroscopyApproach: Using Monte-Carlo diffusion simulations for metabolites, to investigate how a dMRS signal is sensitive to the dendritic spines. Results: Our findings suggests potential biomarkers for characterizing dendritic spines in human brain gray matter using diffusion-weighted MR spectroscopyImpact: This work establishes a benchmark for spine sensitivity and quantification. Also it offers potential dMRS acquisition parameters for spine detection in human brain.
Investigation of the time- and frequency-dependence of diffusion kurtosis in the human brain with pulsed and oscillating gradient experiments
Authors: Hao Runpu , Michael Eric , Hennel Franciszek , Pruessmann Klaas
Published: November 2024

Motivation: Investigation of the time- and frequency-dependence of diffusion kurtosis, a valuable probe of microstructure and exchange, is becoming feasible in humans due to advances of gradient hardware. Goal(s): To provide more data regarding time- and frequency-dependent diffusion kurtosis in the human brain. Approach: Diffusion MRI with pulsed and oscillating gradients (PGSE/OGSE) at different but partially overlapping diffusion times using a head gradient insert and spiral readouts. Results: Biphasic kurtosis behavior (i.e., increase with time in the short-time range and decrease with time in the long-time range covered by OGSE/PGSE, respectively) was observed, with an explainable mismatch between both sequences in the overlapping range. Impact: Studying the time- and frequency-dependence of diffusion kurtosis using both PGSE and OGSE experiments over a range of diffusion times and length scales can provide valuable information about brain tissue complexity, heterogeneity, and inter-compartmental water exchange.
3D-Yarnball Acquisition and Reconstruction Advancement Yields High Resolution T1-Weighted Whole Brain Images in Just Over 1 Minute
Authors: Stobbe Rob , Baron Corey , Beaulieu Christian
Published: November 2024

Motivation: This study is motivated by the creation of high-resolution T1-weighting whole brain images in considerably less time (1 minute) than currently required for standard MP-RAGE (~4 minutes). Goal(s): The sampling efficient 3D-Yarnball trajectory offers a potential imaging solution, but trajectory/sequence design and reconstruction aspects remain to be explored. Approach: Variably under-sampled Yarnball trajectories with 2-10 ms duration were compared in healthy brain, along with different methods of steady-state sequence excitation. Iterative, off-resonance correcting, wavelet-regularized reconstruction was applied to Yarnball for the first time. Results: Yarnball sequence and reconstruction consideration enabled high-quality 0.77 mm isotropic whole brain images in 1 minute Impact: The image acquisition, sequence, and reconstruction investigation of this work enabled robust, high-quality 0.77 mm isotropic T1-weighted whole brain images in just over 1 minute. The goal of this work is to facilitate considerably shorter MRI protocols.
Echo-planar Imaging-based Rapid Simultaneous MR Angiography and Venography with Dedicated Flow-related Ghosting Suppression
Authors: Wu Yue , Yang Yan , Weng Dehe , An Jing , Zhuo Yan , Xue Rong , Zhang Zihao
Published: November 2024

Motivation: Ghost artifact of large vessels impede the use of echo-planar imaging(EPI) for accelerated MR Angiography(MRA) or MR Venography(MRV) acquisitions. Goal(s): To analyze the physical principles of flow-related ghost, and develop targeted technical approaches to suppress the artifact, enabling EPI-based rapid and high-fidelity simultaneous MRAV. Approach: By employing techniques including point-spread function modeling, alternating flow-compensation scheme, flow-related phase-based reconstruction, and automatic detection and correction algorithms, rapid in-vivo vascular imaging were achieved. Results: DEPSAV-II achieved cerebral MRAV with suppressed ghost artifacts and comparable vascular depiction with GRE-based methods in 6 minutes, thereby improving the accessibility of comprehensive vascular examination in routine clinical practices. Impact: Developed a suite of techniques to overcome flow-related ghosting of large vessels which tackling EPI-based rapid arteriovenous-imaging methods. DEPSAV-II’s simultaneous MRAV and significant time-reduction may benefit clinical studies and practices like small vessel diseases requiring comprehensive arterial and venous examination.
Arc-ZTE: Incoherent k-space sampling in time using continuously-slewed gradients for flexible, dynamic, quiet Zero TE MRI
Authors: Ramachandran Shreya , Wood Tobias , Zhang Gavin , Lustig Michael
Published: November 2024

Motivation: Existing Zero TE methods are constrained due to gradient slew limits between spokes, which hinders their use in dynamic imaging applications. Goal(s): We aim to improve temporal k-space sampling in time by increasing the possible angular distance between consecutive spokes via continuously-slewed gradients, while still maintaining minimal gradient refocusing and minimal acoustic noise. Approach: We parameterize the k-space trajectory using sequential rotations of an arc in k-space, then optimize the rotation angles over metrics for sampling uniformity and refocusing. Results: We demonstrate a proof-of-concept of this trajectory and show improvement over radial ZTE in k-space coverage metrics and reconstructions for various temporal resolutions. Impact: By improving temporal k-space sampling for Zero-TE MRI, our work enables quiet, dynamic imaging with flexible temporal resolution. Potential applications include quiet DCE or respiratory motion-resolved imaging for neonates and other sound-sensitive populations.
Further accelerating spin-echo EPI through combined patterned multislice excitation and SMS acquisition
Authors: Zhou Jiazheng , van Gelderen Peter , de Zwart Jacco , Wang Yicun , Duyn Jeff
Published: November 2024

Motivation: Both the recently introduced patterned multislice excitation (PME) technique and SMS acquisition can be used for faster imaging. Combining these would reduce imaging times further. Goal(s): To demonstrate that the PME is compatible with SMS imaging. Approach: Four RF pulses were combined to achieve acceleration from both SMS and PME. To limit peak RF amplitude, pulse components were time-shifted. The approach was demonstrated using diffusion weighted (DW) imaging at 3T. Results: Close to fourfold acceleration was successfully implemented by combining twofold SMS and PME and evaluated for DW MRI performance versus twofold acceleration based on PME only. Impact: Recently introduced PME approach and SMS can be combined to accelerate the acquisition.
MR Fingerprinting with Dynamic Transmit Shims
Authors: Horger Felix , McElroy Sarah , Hajnal Joseph , Malik Shaihan
Published: November 2024

Motivation: Transmit-inhomogeneities at ultra-high-field cause realized/effective flip-angles to strongly deviate from the nominal. In quantitative MRI, retrospective correction is possible but leads to spatially varying efficiency for parameter estimation. Parallel-transmit enables spatio-temporal modulation of excitation pulses in MR Fingerprinting (PTX-MRF), potentially improving encoding power by filling in regions of poor precision achieved with a static configuration. Goal(s): Investigate an MRF prototype sequence with temporal modulation of parallel-transmit shims. Approach: We sequentially apply different transmit-shims to modulate realized flip-angles and employ temporal low-rank for reconstruction of singular-component-images. Results: We explored the potential and key requirements for PTX-MRF, showing that parallel-transmit could prove advantageous for MRF. Impact: This work is an explorative step towards addressing transmit-field inhomogeneities at ultra-high-field. Its impact is mainly indicating new directions worthwhile investigating, supported by evidence from phantom experiments.
Vendor-Neutral Development and Cross-Center Validation of Flip Angle Modulated 2D Sequential CSE-MRI Technique for Liver Fat Quantification
Authors: Tang Jiayi , Tamada Daiki , Yong Xingwang , Chen Yuting , Fujita Shohei , Starekova Jitka , Kammerman Jeff , Brittain Jean , McMillan Alan , Nielsen Jon-Fredrik , Zaitsev Maxim , Reeder Scott , Bilgic Berkin , Hernando Diego
Published: November 2024

Motivation: 2D sequential chemical-shift-encoded acquisitions with centric encoding and flip-angle modulation (FAM) enables motion-robust and high-SNR liver fat quantification. Originally developed in a single vendor, the performance and relative simplicity of FAM motivate vendor-neutral implementation and validation. Goal(s): Implement FAM in the vendor-neutral framework Pulseq, and determine its feasibility, bias, and reproducibility in a multi-center, multi-vendor study. Approach: Pulseq-FAM was applied in two centers with two vendors on a phantom with controlled PDFF/T1water values, and in volunteers during free breathing. Results: At both centers, Pulseq-FAM shows low bias and good reproducibility in the phantom, and excellent motion robustness and image quality in volunteers. Impact: A vendor-neutral implementation of motion-robust liver fat quantification, as demonstrated in this study, may enable detection, staging, and treatment monitoring of steatotic liver disease with improved availability and standardization.
Dynamic interleaved radial amine CEST and sodium (INTERLACED) at 3T
Authors: Kolkovsky Alfredo Lopez , Wang Chencai , Yao Jingwen , Ellingson Benjamin
Published: November 2024

Motivation: Sodium (23Na) and advanced 1H MRI provides valuable metabolic information but are not routinely used because of the required additional scan time. Goal(s): Employ the idle times in 23Na MRI to perform 1H measurements, reducing total scan time. Approach: An interleaved radial amine CEST and sodium pulse sequence was developed to simultaneously acquire acidity or T2* maps simultaneously with salinity maps in phantoms and in the lower leg during an exercise paradigm. Results: A scan reduction of 46% relative to sequential acquisitions. Dynamic T2*, acidity and sodium changes were successfully tracked and in line with the expected physiological responses. Impact: The achieved scan time reduction could facilitate the inclusion of sodium and advanced 1H imaging in clinical routine. Furthermore, it could benefit functional studies by providing dynamic multinuclear information simultaneously from the same transient state.
Metabolic neuroimaging of ApoE and APP mutational status in mouse models of Alzheimer’s disease
Authors: Gao Xiao , Radoul Marina , Guglielmetti Caroline , Le Page Lydia , Li Huihui , Sei Yoshitaka , Huang Yadong , Nakamura Ken , Chaumeil Myriam
Published: November 2024

Motivation: As metabolic impairment is key in AD, metabolic imaging could potentially improve diagnosis and monitoring of AD. Goal(s): Our goal is to determine which metabolic imaging approach, or combination of approaches, provide the optimal set of biomarkers for AD. Approach: We combined three metabolic imaging methods, 1H MRS, HP 13C MRSI and 18F-FDG PET, with machine learning to characterize the neurometabolic profiles linked to AD-related risk factors, namely ApoE mutation, APP mutation, and sex in AD mouse models. Results: Combining metabolic neuroimaging and machine learning can help discriminate between AD-related mutational status (APP and ApoE) and provide information of AD-related sexual dimorphism. Impact: Knowing which metabolic imaging approach(es) is/are optimal to monitor progression in each subset of AD patients, based on sex and mutational status, would improve patient-centric clinical care and potentially create new avenues for assessment of new metabolism-targeting therapies.
In-vivo evidence for cell body loss in cortical lesions in people with multiple sclerosis
Authors: Krijnen Eva , Noteboom Samatha , Lee Hansol , Chiang Florence , Steenwijk Martijn , Schoonheim Menno , Klawiter Eric , Huang Susie
Published: November 2024

Motivation: Cortical lesions are linked to irreversible cortical atrophy as well as cognitive impairment in multiple sclerosis. High-gradient diffusion MRI is sensitive to the microstructural substrate of neurodegeneration in multiple sclerosis. Goal(s): To identify in-vivo patterns of cell body density alterations, quantified by advanced diffusion MRI, in and surrounding focal cortical demyelination in people with multiple sclerosis. Approach: The intra-cellular signal fraction, reflective of cell body density, was compared between cortical lesions, perilesional and normal-appearing cortex. Results: Multiple sclerosis-related decreases in intra-cellular signal fraction were seen in cortical lesions compared to perilesional and normal-appearing cortex. Impact: High-gradient diffusion MRI has the potential to identify cortical cell body loss in-vivo, potentially attributable to focal demyelination, relevant for cognition.
Obstructive Sleep Apnea: Feasibility of Concurrent Evaluation of Neurometabolic Rate and Upper Airway Architecture During Sleep in the Scanner
Authors: Wehrli Felix , Langham Michael , Wiemken Andrew , Xu Jing , Detre John , Dennison Jeffrey , Schwab Richard
Published: November 2024

Motivation: Obstructive sleep apnea (OSA) is a common disorder predisposing patients to heart disease, stroke, and cognitive dysfunction. Goal(s): To gain insights into the association between brain metabolism and changes in upper airway architecture during spontaneous apneas during sleep in the scanner. Approach: A time-resolved pulse sequence was designed that yields neurometabolic parameters and airway anatomy at 6-second temporal resolution, along with EEG monitoring during a 90-minute scan. Results: Data demonstrate associations between transient airway architectural changes and brain vascular-metabolic alterations, notably a steep drop in cerebral metabolic rate of oxygen (CMRO2) during sleep and following apneic events, providing new insight into the disorder. Impact: Understanding the acute structural and neurometabolic consequences of apneic events in obstructive sleep apnea will provide new insight into the disease and provide a method to evaluate the response to treatment.
Identifying Multiple Sclerosis Lesion Subtypes with Distinct Microstructural Features using Advanced Microstructural MRI
Authors: Shin Hyeong-Geol , Dewey Blake E. , Brabec Jan , Zhang Jinwei , Ezzedin Omar , Ecoff Kaitlyn , Kim Anna , Ramirez Alexandra , DuVal Anna , Fitzgerald Kathryn , Knutsson Linda , Szczepankiewicz Filip , Prince Jerry , Saidha Shiv , Calabresi Peter A. , van Zijl Peter , Li Xu
Published: November 2024

Motivation: Conventional MRI struggles to capture heterogeneous histopathological subtypes within multiple sclerosis (MS) lesions, mainly due to a lack of microstructural specificity. Goal(s): (i) To unveil distinct subtypes of microstructural alteration MS lesions using advanced multi-contrast microstructural MRI; (ii) increase sensitivity to individual microstructure. Approach: K-means clustering was applied to multi-contrast microstructural MRI quantities, including parameters from diffusometry (μFA [axonal integrity marker], MD), susceptometry (QSM, 𝜒dia [demyelination marker] 𝜒para [marker for iron-laden microglia]), and relaxometry (R2*, R2, T1). Results: Five MRI-driven lesion subtypes, each with unique microstructural property combinations, revealed potential histopathological features of MS lesions and showed enhanced sensitivities to clinical outcomes. Impact: We used a novel imaging multi-biomarker for in-vivo MS pathology to assess lesion types for potential treatment monitoring in MS. Some MS subtypes with microstructure alterations, potentially related to disease histopathology, showed improved clinical sensitivity over conventional imaging markers.
Blood and CSF Dynamics During One Cardiac Cycle in the Healthy Brain Measured with Cine Phase-Contrast MRI
Authors: Muccio Marco , Sun Zhe , Li Chenyang , Chu David , Minkoff Lawrence , Ge Yulin
Published: November 2024

Motivation: Quantitative analysis of blood and CSF flow dynamics is vital to understand the intracranial pulsating fluid movement environment and its role in brain homeostasis. Goal(s): To characterize the correlation between blood (arterial/venous) and CSF flow within one cardiac cycle. Approach: Flow dynamic measurements in neck arteries and veins, cervical CSF (CSFc) and CSF in the aqueduct of Sylvius (CSFAq) were obtained using cine phase-contrast MRI from 18 healthy volunteers. Results: Net blood and CSFc flow wave curves depict a compensatory mechanism resulting in balance of total fluid inflow and outflow. CSFAq flow patterns mimic CSFc ones with some temporal delay. Impact: Understanding how blood and CSF flow influence each other in healthy subjects provides a reference frame to investigate alterations caused by neurological disease. We showed a dynamic interplay between neck blood and CSF flow at the cervical and aqueduct level.
Detection of vasomotion in the human brain using Fourier decomposition of T1-weighted Cine-FLASH MRI (FD-FLASH)
Authors: Taso Manuel , Mestre Humberto , Aguirre Geoffrey , Detre John
Published: November 2024

Motivation: Vasomotion has been hypothesized as a mechanism for brain paravascular clearance, which could be impaired in multiple neurodegenerative conditions. Goal(s): To measure vasomotion in vivo in human brains using MRI. Approach: A single-shot T1-weighted Cine-FLASH sequence was optimized to provide high temporal resolution in two adults, as well as during a visual stimulation paradigm in one. We performed a Fourier decomposition of the signal in brain vascular structures. Results: An ultra-low-frequency signal was observed consistent with vasomotion in posterior cerebral arteries while no such signal could be identified in the parenchyma. A substantial amplification of this signal could be observed during visual stimulation. Impact: This method could help studying brain waste clearance and its dysfunction in humans in vivo.
T2 selective saturation labeling for imaging of water exchange between tissues and CSF.
Authors: Alsop David , Jaafar Narjes , Taso Manuel
Published: November 2024

Motivation: Water exchange between tissue and CSF may contribute to CSF production and glymphatic clearance. The large difference in T2 between tissue and fluid suggests T2 saturation transfer can be used to image this exchange. Goal(s): We aimed to develop a method for water exchange imaging using T2 saturation. Approach: A novel strategy to control for systematic errors from direct effects of T2 saturation on fluid is proposed and evaluated in healthy volunteers. Results: Three dimensional images at longer TE show exchange signal surrounding the choroid plexus, but also more modest exchange near the cerebellar vermis and the cerebellar and cerebral cortices. Impact: A new strategy for T2 selective water exchange imaging can enable in vivo studies of CSF exchange that may reflect changes in glymphatic clearance or CSF production with aging, Alzheimer’s disease, intracranial hypertension and other disorders.
Test-retest reliability of coupling between cerebrovascularoscillations and cerebrospinal fluid flow fluctuations
Authors: Zhao Weiwei , Mao Tianxin , Deng Yao , Rao Hengyi
Published: November 2024

Motivation: The coupling strength of global blood-oxygen-level-dependent (gBOLD) signals and cerebrospinal fluid (CSF) inflow have been suggested to be an indicator of glymphatic system function. However, few studies have validated its test-retest reproducibility. Goal(s): To assess the reproducibility of gBOLD-CSF coupling. Approach: Thirteen adults of the sleep deprivation (SD) group and 14 adults of the control group underwent three fMRI. The reliability of gBOLD-CSF coupling was evaluated by the intraclass correlation coefficient (ICC). Results: A higher ICC (0.525, P = 0.001) was observed in the control group compared with the SD group (0.137, P = 0.086). Impact: The gBOLD-CSF coupling shows good reproducibility, but care should be taken when interpreting longitudinal changes of the gBOLD-CSF coupling that may be influenced by participants’ drowsiness. Sleep should be considered an important factor in future studies exploring the glymphatic system.