bluuebunny/crossref_metadata_2025 huggingface dataset:
Image sequence partitioning in CRNN-based reconstruction improves ventilation defect detection of 3D-PREFUL with undersampled data
Authors: Zubke Maximilian , Klimeš Filip , Voskrebenzev Andreas , Wernz Marius , Kaireit Till , Kern Agilo , Gutberlet Marcel , Müller Robin , Wacker Frank , Vogel-Claussen Jens
Published: August 2024

3D-phase-resolved-functional-lung (3D-PREFUL) MRI enables a non-contrast-enhanced detection of lung ventilation defects. Convolutional, recurrent neural networks (CRNN) can accelerate data acquisition by reconstructing dynamic lung images from undersampled data. However, a remaining bias in reconstruction led to incorrect detection of ventilation defects. Reducing the number of respiratory phases per reconstruction step improved the accuracy of the defect detection. This improvement is demonstrated by comparison of 2 complementary ventilation defect metrics derived from the original data and the 2x, 4x and 6x undersampled data of Asthma, COPD and post-COVID-19 patients reconstructed from a CRNN in partitions of 30,20 and 10 respiratory phases.
Improving JSENSE Using an Initial Reconstruction with an Unrolled Deep Network Prior
Authors: Saju Gulfam , Li Zhiqiang , Abiri Reza , Liu Tianming , Chang Yuchou
Published: August 2024

JSENSE iteratively optimizes sensitivity maps and the image, so the sensitivity profile can be gradually improved during the reconstruction process. The initially reconstructed image in the first iteration is obtained by the initially estimated coil sensitivity maps. The initial coil sensitivity profiles may be inaccurate and therefore degrade the quality of the subsequent image quality and coil sensitivity map estimation in the iterative optimization process. We propose to use unrolled deep network prior to replace the initial reconstruction in the conventional JSENSE for improving the image reconstruction quality. Experimental results show that the proposed method outperforms CG-SENSE and JSENSE.
MR reconstruction in k-space using Vision Transformer boosted with Masked Image Modeling
Authors: Lee Jaa-Yeon , Park Sung-Hong
Published: August 2024

Masked image modeling (MIM) skim has recently been shown to pre-train vision transform (ViT) and works as an effective data augmentation. In this study, we proposed MR reconstruction algorithm using ViT with MIM in k-space. The proposed method showed better performance than the original 1D and 2D ViT. Our study showed that MIM can be used to enhance the reconstruction quality to help learn the data distribution and that combining the loss in both k-space and spatial domain reconstructs images with better perceptuality.
Highly Accelerated Multi-channel 3D Knee Imaging Using Denoising Diffusion Probabilistic Model (DDPM) and GRAPPA
Authors: Liu Ruiying , Kim Jee Hun , Li Hongyu , Huang Peizhou , Li Xiaojuan , Ying Leslie
Published: August 2024

Deep learning methods have achieved superior reconstruction results in MRI reconstruction. Recently, denoising diffusion probabilistic models (DDPM) have demonstrated great potential in image-processing tasks. In this study, we combine denoising diffusion probabilistic models (DDPM) and GRAPPA for highly accelerated 3D imaging. The method sequentially performs DDPM and GRAPPA with specially designed sampling masks such that the benefits of the diffusion model and the availability of multi-channel data can be utilized jointly. Our results demonstrate that the proposed method can achieve an acceleration factor of up to 16 which is the product of the factors achieved by DDPM and GRAPPA alone.
In Vivo Mapping of Muscle Fibrosis: The Influence of Signal Model Inputs
Authors: Hall Mary , Vainberg Yael , Gold Garry , Mazzoli Valentina
Published: August 2024

Fibrosis could be an early sign of declining muscle quality. Short T2*-signal fraction, which can be calculated by fitting a 3-exponential model to UTE data, has been shown to be correlated with collagen content, which is related to fibrosis. However, this type of signal model has 8 fitting parameters, which could result in overfitting to a limited number of echoes. We constrained the signal model 3 different ways, and compared the resulting short T2*-signal fraction values. There were significant differences between methods, demonstrating that these choices can affect parameter values and diagnostic sensitivity of short T2*-signal fraction for fibrosis detection.
Variational Model Augmented Deep Learning for Small Training Data MRI Thigh Muscle Segmentation
Authors: Mohapatra Paramjyoti , Guo Weihong , Yang Mingrui , Lartey Richard , Li Xiaojuan
Published: August 2024

Accurate automatic MRI thigh muscle group segmentation is essential for muscle morphology and composition which are related to osteoarthritis and sarcopenia. Due to challenges caused by lack of contrast between muscle groups, Deep Learning (DL) becomes a more natural choice than traditional model based approaches. It is however expensive to obtain a large amount of training data and DL using small training data often results in overfitting. We use a variational model based segmentation method in conjunction with a Bayesian neural network to optimize the train framework, producing about 1.6% increase in dice coefficients while working with minimal annotated data.
Compact 16T MRI Magnet: Feasibility Study and Risk Reduction
Authors: Xu Minfeng , Buresh Steve , Wu Anbo , Huang Shike , Foo Thomas
Published: August 2024

An electromagnetic design of a 16.0 T MRI magnet using a combination of Nb3Sn and NbTi superconductors has been completed. It consists of a 9.0 T inner Nb3Sn solenoid and a set of outer NbTi coils that produces 7.0 T field, for a combined 16.0 T field. The design revealed very high hoop tensile and axial compressional stresses in the Nb3Sn coil. Alloy-reinforced high-strength Nb3Sn wires were selected for use in this project. For a magnet to operate in a persistent mode, superconducting joints between Nb3Sn wire segments need to be developed. Various joint configurations were attempted with some success.
Susceptibility Managed Optimization (SUMO) : Very HIgh order shimming for Single Voxel Spectroscopy at 7T
Authors: Hetherington Hoby , Kim Junghwan , Terpstra Melissa , Pan Jullie
Published: August 2024

B0 shimming for single voxel spectroscopy (SVS) is of importance due to its role in determining linewidth, accuracy of the analysis and interpretation. However, for difficult brain regions, such as the prefrontal cortex, where shifts of 3-6mm in voxel position can dramatically alter the achieved linewidth in SVS, the lack of a reliable method to predict the achievable homogeneity results in failed studies and/or increased study times. In this work we demonstrate an objective and non-iterative method (SUMO) for voxel positioning that predicts and ensures adequate B0 homogeneity is achievable.
Hyperpolarized 13C Metabolic Imaging of the Human Abdomen with Spatiotemporal Denoising
Authors: Nickles Tanner , Kim Yaewon , Lee Philip , Chen Hsin-Yu , Ohliger Michael , Larson Peder , Wang Zhen , Vigneron Daniel , Gordon Jermey
Published: August 2024

A substantial challenge in hyperpolarized (HP) 13C MRI is the limited signal-to-noise ratio (SNR) of downstream metabolites, which restricts the achievable spatial resolution. To overcome this for large coverage abdominal studies, a patch-based spatiotemporal denoising approach was applied to denoise dynamic imaging data in [1-13C]pyruvate echo-planar imaging (EPI) human datasets. With denoising, a 11.4 ± 1.8 and 8.7 ± 2.4 fold sensitivity gain was achieved for [1-13C]alanine and [1-13C]lactate, along with improved spatial coverage. These results support the potential of spatiotemporal denoising to improve quantification in HP 13C MRI for normal and cancer studies.
Estimation of Metabolite Signals for In Vitro MRI of Glycolytic Flow in Hyperpolarized Carbon-13
Authors: Hsieh Ching-Yi , Lai Ying-Chieh , Lu Kuan-Ying , Lin Gigin
Published: August 2024

Downstream metabolites may have a poor SNR in hyperpolarized carbon-13 MRI, generating apparent exchange rate constant discrepancies when studying glycolytic flow in vivo or in vitro dynamically in real-time. We developed a method for estimating metabolite signal. This approach estimates metabolite signals using kinetic modeling and noise. The process was evaluated using simulations and in vitro studies. In vitro findings were also compared to 13C NMR cell media AUC. Comparing in vitro data from our method and NMR, both demonstrated consistency when uncertainty was included, suggesting that our method can accurately quantify metabolite signals and indicate how glycolytic flow changes.
Assessment of Pulmonary Morphometry using Hyperpolarized 129Xe DWI with Variable-Sampling-Ratio Compressed Sensing Patterns
Authors: Zhou Qian , Li Haidong , Rao Qiuchen , Zhang Ming , Zhao Xiuchao , Shen Luyang , Fang Yuan , Li Hongchuang , Liu Xiaoling , Xiao Sa , Shi Lei , Han Yeqing , Ye Chaohui , Zhou Xin
Published: August 2024

The long acquisition time of hyperpolarized 129Xe multiple b-values DWI made it hard to apply in patients with severe pulmonary diseases. Herein, we proposed a method of variable-sampling-ratio compressed sensing patterns for accelerating hyperpolarized 129Xe DWI. A four-fold reduction in acquisition time was achieved using the proposed method while preserving good image quality. Meanwhile, the method can be used for evaluating pulmonary injuries caused by cigarette smoking.
Regional 17O T2* in Human Brain at 3T
Authors: Song Hao , Saeidi Hamidreza , Fisher Johannes , Özen Ali , Schumann Stefan , Bock Michael
Published: August 2024

Information about T2* relaxation time plays an important role in data acquisition for 17O-MRI. In this work, we investigated the in vivo T2* relaxation time constants of 17O in regional brain tissue at 3T. Overall, regional T2* relaxation times are in a range of 1.5 - 2ms (except for CSF). Additionally, a T2* variation of 0.12ms was found from superficial to deep layers in the insular cortex. Our results indicate that short-TE acquisition strategies are favorable for 17O-MRI of the brain.
Assessment of Alcoholic Impact on Multiple Organs by Dual-frequency Dual-driver Abdominal MR Elastography (MRE)
Authors: Li Jiahui , Owusu Nana , Glaser Kevin , Sui Yi , Simonetto Douglas , Manduca Armando , Venkatesh Sudhakar , Shah Vijay , Ehman Richard , Yin Meng
Published: August 2024

We performed dual-frequency dual-driver abdominal MR Elastography (MRE) on 11 patients with alcoholic hepatitis (AH), and 6 healthy volunteers without known histories of chronic alcohol consumption. Two flexible drivers were placed over the anterior abdominal wall to deliver sufficient shear wave propagation in multiple abdominal organs at two different mechanical frequencies. The liver stiffness (LS) and spleen stiffness (SS) calculated from MRE at 60Hz, and pancreas stiffness derived from 30Hz, all significantly increased in patients with AH, compared with controls. This pilot study indicates the feasibility of dual-frequency dual-driver abdominal MRE to assess the alcoholic impact on multiple organs.
A comparative study of 2D SSFSE with deep learning based reconstruction and 3D FIESTA in the assessment of active inflammation in Crohn’s Disease
Authors: Wang Yan , Cheng Jingyun , Liu Weiyin , Zha Yunfei
Published: August 2024

Higher resolution and better image quality of 3D FIESTA sequence is used for evaluating bowel inflammation in CD; however, we found 2D SSFSEDLwith significantly higher SNR and CNR of ileum and terminal ileum than 3D FIESTA and, of course, conventional 2D SSFSE. 2D SSFSEDL shortened scan time and also offered better image quality than 3D FIESTA in assessment of bowel inflammation in CD. The SSFSE sequence alone has been considered sufficient in lesion detection[2]; SSFSE with DLR has great potential in elevation of detection rate without extra imaging time.
Longitudinally Evaluation of Locally Advanced Rectal Carcinoma Treated with Preoperative Chemotherapy using Time-Dependent Diffusion MRI
Authors: Gong Xiaoling , Shen Yu , Zhang Xiaoxiao , Wu Zhigang , Wang Ziqiang , Wu Bing
Published: August 2024

The effectiveness of neoadjuvant Chemotherapy (NACT) is most commonly assessed by the change in tumor size based on conventional rectal cancer imaging. However, morphologic changes often occur later during treatment. Time-Dependent Diffusion MRI (TD MRI) is a novel MRI tool for depicting cellular microstructures. This study aimed to investigate the feasibility of Time-Dependent Diffusion MRI–based microstructural mapping for noninvasively characterizing cellular properties of LARC during NACT.
Evaluation of Diffusion Kurtosis Imaging in Prediction of P53 Expression in Rectal Cancer
Authors: Chen Anliang , Dong Deshuo , Ma Changjun , Liu Ailian , Song Qingwei
Published: August 2024

Mutant P53 promotes tumor cell proliferation, invasion, and resistance to chemotherapy. The purpose of this study was to evaluate the value of Diffusion Kurtosis Imaging (DKI) for prediction of P53 expression status in rectal cancer. The results indicate that positive P53 status group had significantly lower MD and higher MK values than negative P53 status group. DKI reflect a non-Gaussian phenomenon of water molecules within biologic tissues for prediction of P53 expression status in rectal cancer.
The predictive value of left ventricular strain analysis in myocardial infarction with ventricular remodeling
Authors: Chen Jing , Mu Xiaolin , Ke Tianyu , Song Yang
Published: August 2024

The subtle changes of myocardial strain in patients with myocardial infarction complicated with ventricular remodeling remain unclear. We used the CMR-FT technique to investigate the degree of strain damage, the degree of scar tissue penetration and the long-term prognostic value after ventricular remodeling in 41 patients with old myocardial infarction. The results showed that the myocardial strain was of great value in quantitatively assessing the degree of myocardial damage, identifying the degree of scar tissue penetration in infarcted myocardium and predicting the long-term end events, especially GLS, which was the best predictor
Improving Brain Volume Measurement Workflow using combination of CS-MRI and Deep Learning based Super-Resolution
Authors: Suwannasak Atita , Yarach Uten , Sangpin Prapatsorn
Published: August 2024

For brain volume measurement (BVM), High-resolution (HR) MR images have shown to provide accurate results at small subcortical areas. However, prolonged scan time remains a classical challenge for 3D MRI. We implemented a combined technique, deep learning based super-resolution (DL-SR) and low-resolution Compressed Sensing (CS) 3D-TFE-T1W with acceleration factor 4 to generate Super-resolution (SR) images under one minute scan time. The results show that DL-SR model is able to improve image resolution, in which no significant differences (p>0.01) in quantitative volumetric measurement between reference and DL-SR at subcortical regions, except for caudate region.
CNN-based three-dimensional superresolution technology in Brain MRI with generalized q-sampling imaging
Authors: Shin Chun-Yuan , Chao Yi-Ping , Kuo Li-Wei , Chang Yi-Peng Eve , Weng Jun-Cheng
Published: August 2024

Understanding neural connections helps scientists conduct cognitive behavioral research. There are many nerve fiber intersections in the brain that need to be observed, and the size is between 30-50 nanometers. Improving image resolution has become an important issue. Generalized q-sampling imaging (GQI) was used to reveal the fiber geometry of straight and crossing. However, it is difficult to accurately describe fiber bending, fanning, and diverging with low-resolution imaging. In this work, we tried to achieve superresolution with a deep learning method on diffusion magnetic resonance imaging (MRI) images that has the potential to assess crossing, curving, and splaying fiber structures.
Increased Resolution and Shortened Scan Time of T2 weighted Prostate MRI using Deep Learning Denoising Reconstruction at 1.5T
Authors: Do Hung , Berkeley Dawn , Tymkiw Brian , AlGhuraibawi Wissam , Kadbi Mo
Published: August 2024

In prostate MRI, high SNR images are desired for a better depiction of anatomical and pathological structures; however, it often requires a longer scan time, especially at 1.5T. Deep Learning Denoising Reconstruction (DLR) has been shown to effectively remove noise, allowing high SNR with higher resolution and shortened scan time simultaneously. This study demonstrates that DLR enables the acquisition of high SNR images with 29.48% scan time reduction and 31.51% increase in spatial resolution at 1.5T.
Diffusion Tensor Imaging in the Lower Leg of a Preclinical Model of Amyotrophic Lateral Sclerosis
Authors: Mathew Ethan , Semmineh Natenael , Fuentes Alberto , Healey Deborah , Dortch Richard , Damon Bruce , Quarles Chad
Published: August 2024

This study examined changes in diffusion tensor parameters during amyotrophic lateral sclerosis progression using a transgenic rodent model. DTI was performed at four timepoints with an even amount of male and female rats to probe sex differences. Leg muscles were excised following scanning for histological analysis. Sex had a statistically significant effect on all parameters. Mean, radial, and axial diffusivity as well as the second eigenvalue were the most sensitive markers of disease progression.
Quantitative MRI of the upper arm in Duchenne muscular dystrophy: Consistent slice positioning is crucial due to fat-fraction variability
Authors: Cakici Michel , Cameron Donnie , Naarding Karin , Niks Erik , Kan Hermien
Published: August 2024

Skeletal muscle fat fraction determined using quantitative MRI is a promising outcome measure in Duchenne muscular dystrophy (DMD). However, fat fraction varies along the length of muscles in the lower limb, hampering consistency of longitudinal assessments. Our results show that fat fraction also varies over muscles in the upper limb. This variability is reduced when assessments are standardized at 40% of the humerus length. This is important for reproducibly measuring the fat fraction in the muscles of the upper limb in DMD in clinical trials and follow-up.
Automatic Alignment of Ex-vivo Brain Pathology to 7T structural MRI
Authors: Li Jinghang , Farhat Nadim , Berardinelli Jacob , Mettenburg Joseph , Aizenstein Howard , Kofler Julia , Ibrahim Tamer
Published: August 2024

In this work, we present an image alignment pipeline that facilitates ongoing Alzheimer’s disease (AD) white matter pathology studies. Following our recently developed ex-vivo 7T cutting-guide container [1], in this work, we demonstrate a standardized alignment (between histopathology and ex-vivo 7T MRI) procedure that significantly reduces human effort and eliminate the need for manual alignment.
Lumped inductors in RF resonators decrease the B1 fields in samples at ultrahigh fields
Authors: Zhao Yunkun , Zhang Xiaoliang
Published: August 2024

This study investigates the effect of lumped inductors used in RF resonant circuits on the magnetic field strength generated by the radiofrequency (RF) coils. The results show that the lumped inductors can reduce B1 fields in samples.
SNR Visualization: A Toolbox for Locating Flexible Coil Arrays
Authors: Malik Pulkit , Wynn Tracy , Fischer Peter , Haemer Gillian
Published: August 2024

We present a MATLAB based visualization toolbox for locating coil elements and evaluating SNR for flexible coil arrays. The greater variation in coil positioning creates challenges for SNR comparisons. By locating coils with coil sensitivity isocontours, the SNR of individual channels can be evaluated while the coil array is flexed. This is used to examine the repeatability of placement, and changes to coil coupling in the different placements. The coil locations can be validated using the SNR visualization displayed as slices, lines, and probe points. Expectations of the SNR field shape are used to further optimize coil locations.
A screen-printed and electroplated 4-channel receiver array coil for veterinary imaging
Authors: Sousa Camila , Gerges Tony , Dimeglio Florent , Gnanago Jean-Lynce , Gilmus Valernst , Lombard Philippe , Dorez Hugo , Cabrera Michel , Lambert Simon
Published: August 2024

In this work, we present a 4-channel receiver array entirely dedicated to veterinary imaging. For this purpose, we have fabricated an array coil on a flexible substrate using silver-ink screen printed process and copper electroplating. This flexible and conformable array coil has the potential to improve veterinary diagnosis with small form-fitting elements that allow a better signal to noise ratio performance.
Determination of the Optimum Permittivity of High-Permittivity Pads when Dipoles are Used as Transmit Coils for the Chest
Authors: Carluccio Giuseppe , Collins Christopher
Published: August 2024

High-Permittivity Materials are often used to manipulate the radiofrequency field B1. Optimization of the permittivity depends on the geometry of the pad, of the subject and of the coil. In this work we determine the permittivity of two pads positioned around the torso, having thickness 1.5 cm and 3 cm, when a dipole array is used to provide the highest transmit efficiency in the heart. The pads provide an improvement of the transmit efficiency of 9.5% and 7.6% for the 1.5 cm and 3cm case respectively, while providing a SAR reduction of 20.2% and 12.5%.
Numerical investigation of multi-turn wireless RF coil for MRI
Authors: Lu Ming , Zhang Xiaoyang , Yan Xinqiang
Published: August 2024

Standard RF coils require preamplifier models, baluns, coil plugs, and coil ID circuits, which makes coils bulky and expensive. A more affordable way to achieve as high SNR as the standard local receive coil is using the inductively coupled wireless coil. In this work, we numerically investigate whether the multi-turn wireless coil with a similar structure as the stacked coil can enhance the SNR.
An add-on local external shim array to improve the main magnetic field homogeneity in the prostate
Authors: Tenbergen Carlijn , Stamatelatou Angeliki , Nassirpour Sahar , Chang Paul , Scheenen Tom
Published: August 2024

B0-field inhomogeneities can influence (spectroscopic) image quality of the prostate, causing geometric distortion in diffusion weighted EPI images as well as line broadening in MRSI voxels. We added a 16-element external local shim array around the pelvis to improve B0-field homogeneity within the prostate and evaluated its effects compared to standard shimming in 9 healthy volunteers. Resulting B0-maps showed a comparable or reduced frequency variation across subjects, with a significant decrease of MRSI citrate line widths. DWI did not show a robust effect over the group of subjects.
Reproducibility of Cardiac 31P MRS at 7 T – Initial Results of a Multi-Center and Longitudinal Study
Authors: Wampl Stefan , Valkovic Ladislav , Mozes Ferenc , Meyerspeer Martin , Schmid Albrecht
Published: August 2024

To demonstrate reproducibility of cardiac 31P MR spectroscopy at 7T, three subjects were scanned on two sites in two different countries. The two sites are equipped with similar MR scanners but scanner platform versions, RF coil hardware and operators differed. The 16-channel receive array at site A provided 50% higher SNR than the 14cm single loop coil at site B, while site B achieved better linewidths, resulting in similar quality of spectral fitting. Two scan protocols were compared between the sites, both provided good reproducibility of cardiac PCr/ATP. This demonstrates the feasibility of larger multi-centre trials of cardiac MR spectroscopy.
Improving microstructural estimation in time-dependent diffusion MRI model with a Bayesian method
Authors: Liu Kuiyuan , Zheng Tianshu , Ba Ruicheng , Zhang Hongxi , Wu Dan
Published: August 2024

In this study, we proposed Bayesian estimation of tissue microstructures in td-dMRI model, and compared its performance with the traditional non-linear least square fitting method in simulation data and glioma patient data. We found that the performance of Bayesian fitting was dependent on the prior distribution and choice of hyperparameters, and the combination of Bayesian and least-square fitting could achieve reasonable performance without prior information.
Mapping Myelin Volume Fraction using Multiple Echo Gradient Echo and Dictionary Matching
Authors: Şişman Mert , Romano Dominick , Dimov Alexey , Kovanlikaya Ilhami , Spincemaille Pascal , Nguyen Thanh , Wang Yi
Published: August 2024

Myelin Volume Fraction (MVF) is an important biomarker of demyelination various diseases Multiple Sclerosis. In this study, we propose a method that provides quantitative MVF maps from routine multiple echo gradient echo acquisitions and dictionary matching. The dictionary is generated using the Hollow Cylindrical Fiber Model (HCFM) and employs both the magnitude signal decay and QSM obtained from the mGRE phase. The obtained maps show both qualitative and quantitative superiority over the standard multiexponential fitting-based myelin water fraction (MWF) maps.
A new qMRI approach for mapping microscopic water populations and tissue relaxivity in the in-vivo human brain
Authors: Filo Shir , Mezer Aviv
Published: August 2024

We present an array of new quantitative maps, highlighting different aspects of the tissue’s water. Furthermore, our technique allows to calculate the voxel-wise tissue relaxivity, associated with the molecular composition of the brain. Our approach is based on the pioneering two-site exchange model. We implemented it for magnetization-transfer weighted water content mapping of brain tissue for the first time. The new in-vivo MRI measurements conform well with the theory. They can be easily acquired with the standard quantitative MRI protocol and do not require complex data fitting. Therefore, the proposed technique may further advance human brain research and diagnosis.
Probing restriction and exchange in the human brain using free waveforms on a high-performance gradient system
Authors: Chakwizira Arthur , Zhu Ante , Foo Thomas , Westin Carl-Fredrik , Szczepankiewicz Filip , Nilsson Markus
Published: August 2024

Monitoring time dependence with diffusion MRI provides observables sensitive to restricted diffusion and exchange. Probing these phenomena by simply varying the diffusion time is a challenge because they have opposite effects on the diffusion-weighted signal and may cancel each other. A theoretical framework was recently proposed for disentangling the effects using free gradient waveforms. Here we explore the potential of the approach for neuroimaging in vivo using a high-performance gradient system. Results demonstrate unprecedented ability to disentangle the effects of restriction and exchange. Maps of the exchange rate show plausible contrast in both cortical and subcortical regions of the brain.
Hyperpolarized 15N choline chloride to study choline metabolism in prostate cancer at 7T.
Authors: Dominguez-Viqueira William , Estrella Veronica , Ruiz Epifanio , Martinez Gary , Choi Jung
Published: August 2024

Elevated concentrations of choline and phosphocholine are known to be a metabolic hallmark for tumor hypoxia in prostate cancer. An inhibition of hyperpolarized 15N choline to phosphocholine conversion is shown in this work in hypoxic PC-3 cells in-vitro as seen by other methods in the literature. In-vivo tumor volumes and hyperpolarized 15N phosphocholine to choline ratios were measured in twelve NSG mice with subcutaneous flank xenograft PC-3 tumors, showing a moderate correlation. The findings in this work support the hypothesis that hyperpolarized 15N-Choline may be useful as a marker of malignancy.
SABRE Hyperpolarization of Bulky, Nitrile Containing Anti-Cancer Drugs, Letrozole and Anastrozole, with Long Hyperpolarization Lifetimes
Authors: Macculloch Keilian , Browning Austin , TomHon Patrick , Lehmkuhl Soren , Checkmenev Eduard , Theis Thomas
Published: August 2024

Signal Amplification By Reversible Exchange in Shields Enable Alignment Transfer to Heteronuclei (SABRE-SHEATH) was employed to boost 15N magnetic resonance sensitivity on common anti-cancer agents. The SABRE-SHEATH hyperpolarization dynamics of letrozole and anastrozole were independently optimized with respect to solution temperature and polarization transfer field. These studies enabled single scan 15N detection of the drugs at natural isotopic abundance working with mM concentrations for over 30 minutes, paving the way for more sensitive drug development.
Factors influencing human brain metabolite SNR in studies with hyperpolarized [1-13C]pyruvate
Authors: McLean Mary , Grimmer Ashley , Latimer Elizabeth , Khan Alixander , Wodtke Pascal , Kaggie Joshua , Grist James , Zaccagna Fulvio , Graves Martin , Gallagher Ferdia
Published: August 2024

Human brain metabolite SNR in studies with hyperpolarized [1-13C]pyruvate was found to best correlate with percentage polarization in the liquid state and with the polarization adjusted for pyruvate concentration and the delay between dissolution and injection (‘injectable signal’). It did not depend on the volume of pyruvate injected, suggesting that the current dose (which is adjusted by body weight) is adequate. It may be worth further exploring whether the SNR of bicarbonate could be enhanced by a longer delay between injection and the start of acquisition. Liquid and solid-state polarizations did not correlate, highlighting the importance of liquid state measurement.
Para-hydrogen signal-enhanced 1-13C-pyruvate-d3 for rapid metabolic tumor imaging
Authors: Schroeder Henning , Hune Theresa , Mamone Salvatore , Jagtap Anil , Sternkopf Sonja , Stevanato Gabriele , Korchak Sergey , Fokken Claudia , Müller Christoph , Becker Dorothea , Schmidt Andreas , Glöggler Stefan
Published: August 2024

Using a Parahydrogen-induced polarization (PHIP) based approach, we enhanced the signal of pyruvate, one of the key metabolites for energy production in the body. By injecting this metabolite into a mouse carrying a human melanoma tumor, we could perform real time spectroscopy and visualization of the tumors metabolism using a NMR machine. This offers a fast and powerful tool for metabolic imaging without using radio tracers.
Brain tumor segmentation using out-of-distribution feature from normal MR images
Authors: Jeong Namho , Kang Beomgu , Park Hyunwook
Published: August 2024

Abundant data of healthy subjects is available and thus it would be helpful if normal data can boost the brain tumor segmentation. We proposed the out-of-distribution (OOD) feature based on the learned distribution of normal data to discriminate abnormal tumors. Once the neural network was trained to synthesize other contrast MR images with normal data, it failed to properly synthesize the tumor tissues. This OOD characteristic was used for the generation of new feature that can help the tumor segmentation. It was verified that the OOD features contributed to an improvement of segmentation through experiments.
T2 Relaxation Time Decreases in Regions of Loaded Contact in Superficial and Deep Layers of Articular Cartilage
Authors: Bzowey Natasha , Black Marianne , Cui Lumeng , Thorson Chelsey , Martel Madeline , McWalter Emily
Published: August 2024

The aim of this work was to identify focal changes in T2 relaxation times inside and outside regions of tibiofemoral contact in loaded cadaver knee articular cartilage whole, superficial, and deep layers. We used a cluster analysis approach to identify regions of change in T2 relaxation time. We found that 1) decreases in T2 relaxation time with load appeared predominantly inside of the femoral and tibial cartilage contact areas, and 2) greater decreases in T2 within the tibial and femoral cartilage contact area were observed in the superficial layer of cartilage.
T2 and T1rho mapping of equine metacarpophalangeal joint cartilage
Authors: Lockard Carly , Sutton Brad , Damon Bruce , Li Xiaojuan , McCoy Annette
Published: August 2024

Horses are an excellent translational model of orthopedic disease with high relevance to human disease. T2 and T1rho mapping can provide information about early cartilage changes in a horse post-traumatic osteoarthritis model. We investigated the feasibility of using MAPSS-based T2 and T1rho mapping in the horse metacarpophalangeal joint cartilage in cadaver specimens and live horses with and without joint pathology. MAPSS-based T2 and T1rho mapping of equine metacarpophalangeal joint cartilage is feasible and provides realistic cartilage relaxometry values.
Performance of a rotatable Tx/Rx body coil for MR-guided particle therapy
Authors: Dietrich Kilian , Klüter Sebastian , Debus Jürgen , Ladd Mark , Platt Tanja
Published: August 2024

Electromagnetic field simulations were performed at 1.5T to characterize the imaging capabilities of an RF body coil that is compatible with MR-guided radiotherapy and that can be rotated to achieve a flexible coil to fixed beam orientation. Transmit and receive field characteristics of the RF coil were calculated inside a phantom, and the homogeneity and power efficiency were analyzed for 24 different angles of rotation.
Multiphoton Parallel Transmission (MP-pTx)
Authors: Drago John , Guerin Bastien , Cauley Stephen , Wald Lawrence
Published: August 2024

We introduce multiphoton parallel transmission to mitigate nonuniform excitation in high-field MRI. Following an on-resonance birdcage subpulse, a multiphoton subpulse consisting of a single, off-resonance, high-frequency field from a birdcage coil, is supplemented with low-frequency parallel irradiation from a shim array. RF heating concerns are simplified compared to pTx, because only the birdcage coil produces significant SAR. Using a small-tip forward model, we optimize a nonconvex problem to find the amplitudes/phases of the low-frequency coils. Simulations demonstrate flip angle variation reduction across the brain ROI of 31.5% and NRMSE reduction of 42.0% compared to a conventional 7 T birdcage excitation.
Retrospective Correction of Second-order Concomitant Fields in 3D Perfusion Imaging with a High-performance Gradient System
Authors: Ajala Afis , Lee Seung-Kyun , Abad Nastaren , Foo Thomas
Published: August 2024

Magnetic resonance imaging using 3D stack-of-spirals at 3T on a high-performance gradient system such as the MAGNUS can be subject to strong second-order concomitant magnetic fields (SOCG), which can lead to signal dropout and blurring artifacts that become more significant at locations that are farther from the gradient isocenter. SOCG cannot be corrected by pre-emphasis of gradient waveforms and/or radio frequency modulation alone, and hence requires higher-order hardware or software solution. We demonstrate a software-based correction of SOCG in 3D pseudo-continuous arterial spin labelling with a stack-of-spirals k-space trajectory by nulling the phase contributed by SOCG during reconstruction.
Preoperative Prediction of Hepatocellular Carcinoma with Stem Cell Phenotype on Enhanced Magnetic Resonance Imaging and Its Prognostic Value
Authors: Chen Yidi , Jiang Hanyu , Song Bin
Published: August 2024

Hepatocellular carcinoma (HCC) with stem cell phenotype is characterized by activating classic cell proliferation pathways and altering intrinsic regulators, it can stimulate HCC tumor proliferation, make the tumor more prone to recurrence, metastasis and therapy resistance. In this study, we developed an easy-to-use and noninvasive risk score integrating preoperative clinical indicators and enhancement magnetic resonance imaging (MRI) to predict stem cell phenotype HCC.
The feasibility of 4D Flow in evaluating hemodynamic changes of transplant renal artery stenosis
Authors: Guo Songlin , Wu Peng , Han Lu , Pan Liang , Xing Wei
Published: August 2024

Although 4D-Flow MRI is capable of detecting hemodynamic abnormalities, it is rarely employed in transplanted kidneys. Using 4D-Flow MRI, we assessed total volume, net flux, maximum flow, and mean flow rate and performed a statistical analysis of the correlation in this study. Total volume, net flux, maximum flow, and mean flow rate were shown to be inversely linked to the degree of stenosis in the transplanted renal artery. As a result, 4D-Flow MRI may be applied to study the hemodynamic changes of the transplanted renal artery noninvasively.
MR-based body composition analysis, resting state fMRI and autonomic function evaluation for phenotyping biomarkers
Authors: BANGA CHETNA , BHOSLE DR. PREETI , KUMAR DR. DUSHANT , DEEPAK PROF. K.K , CHANDRAN DR. DINU , JAYASUNDAR PROF. RAMA
Published: August 2024

Phenotyping individuals are gaining importance in personalized medicine. This MR based body composition analysis and resting state (R-fMRI) along with autonomic functions (AFT) evaluation have determined parameters for physical, functional and physiological phenotyping in healthy volunteers (n=30). MR studies (at 3T) were R-fMRI using EPI sequence, subcutaneous fat evaluation by mDIXON sequence and AFT included parasympathetic (deep breathing, HUT) and sympathetic (HUT, hand grip test, cold pressor test). Increased functional activation, higher abdominal fat and fall in Baroreflex independent sympathetic reactivity were observed in volunteers having BMI ≥25 Kg/m2 compared to those with BMI <25Kg/m2.
Comparison of cardiac DWI with and without ZOOM by using second-order motion compensated spin echo for healthy control and HCM patients
Authors: Zheng Jianmin , Wang Yishi , Lian Jianxiu , Li Yijun , Tian Ping , Liu Ying , Zheng Minwen
Published: August 2024

Hypertrophic cardiomyopathy (HCM) is a hereditary cardiomyopathy with a relatively high rate of sudden death. Diffusion-weighted imaging (DWI) is widely used for evaluating motion of water protons as one of the functional magnetic resonance imaging methods. Second-order motion-compensated spin echo (M2SE) has been applied for cardiac DWI, but there are few reports of M2SE combined with ZOOM for HCM. The results showed that both signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of ZOOM-M2SE were significantly higher than those of M2SE only, and the ADC value of hypertrophic cardiomyopathy was also significantly higher than that of healthy controls. Cardiac DWI using ZOOM-M2SE would be a more appropriate method for investigating the myocardial microenvironment in healthy and HCM subjects.
Investigating Diffusion Time Dependent Kurtosis Evolution in Repeated Mild Traumatic Brain Injury in Mice
Authors: Hamilton Jake , Rahman Naila , Xu Kathy , Brown Arthur , Baron Corey
Published: August 2024

Probing the diffusion time dependence of diffusional kurtosis within brain microstructure is being recognized as a valuable method to study various neurological pathologies, however, its use in the study of repeated mild traumatic brain injury (mTBI) has not been explored. In this work, we investigated differences in the time-dependence of diffusional kurtosis in injured and sham mice using oscillating gradient spin echo (OGSE) diffusion kurtosis imaging (DKI). The results of this work show promising differences in kurtosis within the hippocampus of injured and sham mice, illustrating the sensitivity of OGSE DKI in detecting long-lasting pathological microstructural changes following brain injury.
Diffusion filters, T2-filters, diffusion tensor component diffusivities, and compartmental diffusivities. What is happening in FEXI?
Authors: Shin Hyeong-Geol , Li Xu , Heo Hye-Young , Knutsson Linda , Szczepankiewicz Filip , Nilsson Markus , van Zijl Peter
Published: August 2024

We explored how compartmental anisotropy affects filter-exchange imaging (FEXI) data in white matter by applying different types of tissue water magnetization filters, including multi-orientation and spherical tensor encoded diffusion filters, as well as a T2 filter. The results show that, depending on the mutual orientation of the filter and detection gradient pairs relative to fiber orientation, filtering efficiencies can be positive or negative. We conclude that the fast compartment reduced during diffusional filtering need not be extracellular, but can also reflect intra-axonal signal losses with effect size determined by the diffusion tensor components perpendicular and parallel to the fibers.
Investigating Multi-Dimensional Diffusion-Weighted MRI for High-Resolution Post-Mortem Brain Acquisitions at 9.4 T
Authors: Gerbeth Hannah , Paquette Michael , Jäger Carsten , Wenk Patricia , Budinger Eike , Morawski Markus , Eichner Cornelius
Published: August 2024

Diffusion-weighted MRI (dMRI) is a widely used tool to non-invasively study the microstructure of the human brain. However, conventionally employed diffusion tensor imaging (DTI) applications only provide limited information. In contrast, Multi-Dimensional Diffusion Imaging, MD-dMRI, aims to provide a framework for further discrimination between highly complex biological structures. In this context, post-mortem MD-dMRI data play an important role to validate in vivo imaging results. Because the fixation process modifies tissue properties, adapted and optimized acquisition methods are required. Here, we investigate the feasibility to acquire and analyse high-resolution MD-dMRI data from a post-mortem brain tissue sample.
Terminal Airspace Enlargement Measured Using Pulmonary Functional MRI Predicts CT Airway Loss in COPD
Authors: Wyszkiewicz Paulina , Sharma Maksym , Kooner Harkiran , McCormack David , Kirby Miranda , Parraga Grace
Published: August 2024

The onset and progression of chronic obstructive pulmonary disease (COPD) is currently believed to initiate in the small-airways and progresses to emphysema or terminal airspace (alveolar) enlargement and destruction. MRI apparent-diffusion-coefficient (ADC) provides a way to measure subclinical emphysematous destruction in patients. Here we investigated the relationship between pulmonary functional MRI measurements of terminal airspace enlargement using 3He MRI-ADC and CT airway changes in ex-smokers with COPD. MRI-ADC values at baseline were uniquely predictive of worsening CT total-airway-count and airway wall-area after three-years. MRI captures evidence of mild or subclinical emphysema and its relationship with terminal airway obliteration in COPD.
Effect of glucose on the HP 129Xe dissolved phase blood resonances
Authors: Mikowska Lutoslawa , Grynko Vira , Shepelytskyi Yurii , Ruset Iullian , Deschamps Joseph , Aalto Hannah , Targosz-Korecka Marta , Harańczyk Hubert , Balamore Dilip , Albert Mitchell
Published: August 2024

We examined the impact of elevated glucose levels on the chemical shift and T2* relaxation of hyperpolarized 129Xe dissolved in sheep blood. The addition of glucose did not affect the 129Xe-plasma resonance. For the first time, however, we have observed an additional 129Xe dissolved phase resonance attributed to 129Xe bound to glycated hemoglobin. A glucose-related linear downfield shift of the 129Xe resonance frequency was observed for 129Xe bound to native hemoglobin, whereas the T2* relaxation of 129Xe bound to glycated hemoglobin increased non-linearly with increasing glucose concentration.
Enhanced 129Xe T1 relaxation in blood and in presence of SPIONs at low field strengths
Authors: Bryden Nicholas , Atalla Sebastian , Kelley Michele , Holmes Leah , Branca Rosa
Published: August 2024

We demonstrate enhanced T1 relaxation of hyperpolarized 129Xe spins in blood and in the presence of superparamagnetic iron oxide nanoparticles (SPIONs) at low field strengths.
Self-Supervised Learning for Perivascular Spaces segmentation with enhanced contrast knowledge
Authors: Lan Haoyu , Toga Arthur , Choupan Jeiran
Published: August 2024

Due to the absence of isotropic T2w modality in clinical datasets, it is challenging to enhance the PVS contrast using multiple neuroimage modalities. To overcome this issue, in this work we introduced using self-supervised pre-trained model in the enhanced PVS contrast image space to improve the downstream model segmentation performance when solely using T1w as the training data. The experiment results showed that the proposed method increased segmentation accuracy compared to the model trained from scratch using T1w modality and resulted in faster training and less required training data volume.
Assessment of vertebral and intervertebral disc microenvironment changes in postmenopausal women using IVIM and fat-water MRI
Authors: Zhang Shuo , Song Qingwei , Feng Hongbo , Guo Qianrui , Yang Yang
Published: August 2024

Intravoxel incoherent motion (IVIM) and fat-water magnetic resonance imaging (FWMRI) are rarely used for vertebral and intervertebral disc. To search for predictive value of them in assessing the lumbar spine microenvironment changes, we performed a study with postmenopausal women combined the parameters with bone mineral density (BMD) and major fracture risk assessment (FRAX) score. We report that fat fraction (FF) has significant correlation with FRAX, FF was moderately negatively correlated with BMD; ADCslow of intervertebral discs showed moderately negatively correlation with FRAX score and FF. IVIM and FWMRI have potential to become new biomarkers in predicting lumbar spine microenvironment changes.
Can Zero Echo Time (ZTE) Magnetic Resonance Imaging Sequences Detect Signal from Collagen Backbone Protons?
Authors: Moazamian Dina , Chen Xiaojun , Suprana Arya , Xia Andrew Andrew , Jerban Saeed , Malhi Bhavsimran , Carl Michael , Chang Eric , Ma Yajun , Jang Hyungseok , Du Jiang
Published: August 2024

Ultrashort echo time (UTE) and zero echo time (ZTE) sequences have been extensively investigated for imaging of short T2 species. The ZTE sequence has a shorter effective TE than UTE and may be superior in imaging ultrashort T2 species. This study investigated whether ZTE could directly image collagen backbone protons in bovine cortical bone and human patellar tendon samples after D2O exchange and freeze-drying. Our experimental results demonstrate that collagen backbone protons are "invisible" with ZTE, which may not be able to directly image species with T2s of ~10 µs.
Evaluation of Potential Benefits of 7T for Knee Epiphyseal Bone Marrow ASL Imaging
Authors: Li Xiufeng , Ellermann Jutta , Metzger Gregory
Published: August 2024

Knee epiphyseal bone marrow ASL imaging (called knee ASL imaging in the following) is challenging due to very low perfusion in epiphyseal yellow bone marrow mainly consisting of fat cells with a sparse network of capillaries. In general, it is known that higher magnetic fields (i.e. ≥7T) can specifically benefit ASL imaging. However, the specific potential benefits in the knee have not been systematically evaluated to date. We have performed theoretical simulations to explore the potential gain for knee ASL imaging at 7T compared to 3T and present our preliminary experimental results comparing both field strengths.
Linearity and Bias of Bone Marrow Relative Fat-fraction Compared to Proton Density Fat-Fraction
Authors: Mader Matthew , Hernando Diego , van der Heijden Rianne , Reeder Scott , Pirasteh Ali
Published: August 2024

Bone marrow relative fat-fraction (rFF) measured using dual-echo gradient echo (GRE) in- and opposed phase imaging, has been proposed as an early predictor of treatment response in multiple myeloma. In this work we demonstrate that in patients without known bone marrow pathology (referred for liver fat/iron quantification), bone marrow rFF is unreliable and suffers from large bias when compared with proton density fat-fraction (PDFF), acquired using quantitative chemical-shift encoded (CSE) MRI. Hence, PDFF should be considered for future approaches using bone marrow fat-fraction as a predictor of treatment response in multiple myeloma.
Design and Implement Active Twin-T Notch Filter for Signal Reception in Magnetic Particle Imaging
Authors: Huang Kangjian , Liu Congcong , Li Ye , Zhu Yanjie , Zheng Hairong , Liang Dong , Wang Haifeng
Published: August 2024

Because of the imaging coding mode of Magnetic particle imaging (MPI), the drive-field signal directly couples into the receiving coil and covers the magnetic particle signal, which one aims to detect. Therefore, some method is needed to remove the drive-field signal and retain the magnetic particle signal. One of the methods is to use a passive band-stop filter to filter the excitation signal, but the general passive band-reject filter has a large stopband, which filters part of the magnetic particle signal while filtering the drive-field signal. In this study, we design an active twin-T notch filter with narrow stopband, which better restore the magnetic particle signal and improve the signal-to-noise in MPI.