bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary Assessment of Gas Exchange Efficiency in Lung Transplant Patients with Multi-breath Xenon Polarization Transfer Contrast Imaging
Authors: Amzajerdian Faraz , Hamedani Hooman , Baron Ryan , Xin Yi , Achekzai Tahmina , Loza Luis , Ismail Mostafa , Duncan Ian , Kadlecek Stephen , Ruppert Kai , Rizi Rahim
Published: August 2023

Quantifying the exchange of hyperpolarized xenon gas between the airways, lung parenchyma, and red blood cells may provide valuable insights into the progression of lung graft failure, enabling earlier diagnosis of chronic lung allograft dysfunction (CLAD). By combining Xenon polarization Transfer Contrast (XTC) imaging with a multi-breath model of fractional ventilation, gas exchange efficiency was assessed in four lung transplant recipients 3-12 months post-surgery in order to identify baseline metrics and trends.
Advancing SABRE Toward In Vivo Imaging: Phantom Chemical Conversion of Hyperpolarized [1-13C]-Pyruvate
Authors: TomHon Patrick , MacCulloch Keilian , Guarin David , Hardy Erin , Browning Austin , Dedesma Carlos , Rosen Matthew , Yen Yi-Fen , Theis Thomas
Published: August 2023

This work illustrates current advancements in SABRE hyperpolarized pyruvate toward in vivo imaging, demonstrating that significant levels of polarization achieved on pyruvate enable dynamic spectroscopy and imaging of downstream chemical products. Specifically in this study we show the monitoring of chemical conversion of pyruvate to pyruvate hydrate using a pH change and pyruvate to CO2 by reaction with H2O2. While the current work only focuses on the study of the chemical conversion of hyperpolarized substrate in a phantom, these studies lay the groundwork for future in vivo injections that mirror these chemical conversion processes.
semi-LASER MRS at 3T with TR=5s: All the Signal, Similar Scan Time, and Minimal T1 Weighting
Authors: Ensworth Alex , Barlow Laura , Kozlowski Piotr , MacMillan Erin , Laule Cornelia
Published: August 2023

The choice of repetition time (TR) in MR spectroscopy studies is widely debated. A shorter TR results in more clinically acceptable scan times, however due to T1 effects, the metabolite concentrations are reduced. We used semi-LASER MRS to compare the SNR and absolute metabolite concentrations for TR=2,5 and 8s. We demonstrate it is possible to achieve similar SNR and scan time using a TR of 5s with half the acquisitions compared to a TR of 2s, where the metabolite concentrations are 20% lower. Using a TR of 5s for any MRS study is feasible and recommended to minimize T1 effects.
Parahydrogen-Based Hyperpolarization of a Pyruvate Ester to 25% Within an MRI System Using SAMBADENA
Authors: de Maissin Henri , Ivantaev Vladislav , Müller Christoph , Mohiuddin Obaid , Hennig Jürgen , von Elverfeldt Dominik , Hövener Jan-Bernd , Glöggler Strefan , Schmidt Andreas
Published: August 2023

Parahydrogen (pH2) and Synthesis Amid the Magnet Bore Allow Dramatically Enhanced Nuclear Alignment (SAMBADENA) and have recently enabled hyperpolarization (HP) of 13C and subsequent in vivo administration of the produced contrast agent inside an MRI system. pH2 Induced Polarization (PHIP) by Side-Arm Hydrogenation (PHIP-SAH) has extended the portfolio of PHIP agents to metabolically-active molecules such as acetate, lactate, and pyruvate, but typically requires hydrogenation in organic solvents like chloroform. Here we present our new, solvent-compatible SAMBADENA setup and preliminary results of the 13C HP in chloroform of the PHIP-SAH molecule cinnamyl-pyruvate – opening the pathway towards metabolic studies with SAMBADENA.
Simulated Impact of Gradient Amplifier Noise on Simple 3D Sequences: Preliminary Results
Authors: Twieg Mike
Published: August 2023

It is often stated, without qualification, that MRI gradient systems must be precise and/or accurate in order to ensure MRI image quality. Some imperfections (delay, eddy currents) have been well-studied and documented, while others such as noise, ripple, and quantization have not. Here we simulate the impact of white noise in the gradient fields with simple cartesian imaging sequences for a numerical brain phantom. Preliminary results suggest that high-performance/high-cost components typically marketed for gradient control are excessive, and much cheaper components could be used without significant drawbacks (NRMSE < 1%), especially for low-field/low-cost systems.
A resource for development and comparison of harmonisation methods for multi-modal brain MRI data
Authors: Ntata Asante , Mougin Olivier , Bastiani Matteo , Almagro Fidel Alfaro , Campbell Jon , Morgan Paul , Jenkinson Mark , Sotiropoulos Stamatios
Published: August 2023

A key challenge in robustly extracting quantitative information from MRI data is the dependence of derived features on nuisance factors, such as the scanning protocol, hardware and software, which are different between vendors and vary with site. While there exist several harmonisation approaches, what’s missing is objective ways and datasets to compare them. Here we present a novel multi-modal neuroimaging data resource for evaluating and comparing harmonisation approaches based on a “travelling heads” paradigm. We further demonstrate how such a resource can be used to a) map the need for harmonisation for different imaging-derived features, b) evaluate existing harmonisation approaches.
CNN denoising of FGATIR MRI improves direct visualization of subcortical anatomy
Authors: Ades-Aron Benjamin , Elsayed Mohammed , Hoch Michael , Lemberskiy Gregory , Wang Yao , Novikov Dmitry , Fieremans Els , Shepherd Timothy
Published: August 2023

The basal ganglia, thalamus and brainstem are affected by movement disorders and contain key targets for functional neurosurgery. Targeting however is based on indirect coordinates originally derived from pneumoencephalograms! 3D Fast Gray Matter Acquisition T1 Inversion Recovery (FGATIR) can directly visualize potential targeted structures (e.g. dentatorubrothalamic tract), but is signal-starved in clinically-feasible acquisitions. We developed a convolutional neural network to improve FGATIR quality. Expert rater assessment suggested this CNN improved contrast resolution of individual structures and overall clinical image quality of 1-average data to the level of 4-averages. This could further enable investigations of functional neurosurgery for movement disorders.
Diffusion-weighted MRI-based Virtual Elastography is feasibility for the evaluate of Rolandic epilepsy
Authors: Gao Lu , Li Xianjun , Feng Yuying , Jin Chao , Zhang Hua , Li Huanfa , Hu Haipeng , Wei Xiaocheng , Yang Jian
Published: August 2023

Conventional MRI is difficult to discover the subtle changes caused by epilepsy. Virtual magnetic resonance elastography (vMRE) is based on diffusion MRI, which is sensitive for variety of physiologic and pathologic conditions. This study use vMRE to evaluated left Rolandic epilepsy. We found that left precentral gyrus, left postcentral gryus and left superior temporal gyrus is more stiffer than controls. The longer the seizure duration the stiffer of the brain tissues. vMRE has the potential to noninvasive evaluate epilepsy.
Network efficiency of structural covariance networks relate to cognitive performance in children with childhood absence epilepsy
Authors: Eussen Merel , Jansen Jacobus , Voncken Twan , Hall Mariette Debeij-van , Hendriksen Jos , Vermeulen Jeroen , Klinkenberg Sylvia , Backes Walter , Drenthen Gerhard
Published: August 2023

Cognitive deficits have been reported in children with childhood absence epilepsy (CAE). Regional alterations in morphology in children with CAE are likely related to the changes in the underlying network structure. Structural covariance networks (SCNs) based on interregional correlations of cortical thicknesses can describe these changes. To relate cognitive performance to network efficiency, individual SCNs are derived from anatomical MR images of the control group and one patient. The global efficiency calculated from the resulting SCNs showed a negative relation with cognitive performance for children with CAE.
A Graph Theoretical Approach for Lateralization of Temporal Lobe Epilepsy Using Nodal Functional Connectivity
Authors: Fallahi Alireza , Pooyan Mohammad , Mehvari-Habibabadi Jafar , Tabatabaei Narges Hoseini , Ay Mohammadreza , Nazem-Zadeh Mohammad-Reza
Published: August 2023

In this study, six graph theoretical measures were identified as nodal level epileptogenicity in TLE patients using functional connectivity analysis. The aim of this study is to define brain nodes that have significant difference between left and right TLE patients using resting state functional connectivity analysis. Clustering coefficient, degree centrality, betweenness centrality, node neighbor’s degree, closeness centrality, and page rank were calculated as graph theoretical characteristics and multi-dimensional scaling (MDS) was used as a statistical method. Results of the applied method suggested significant nodes for prediction of laterality in TLE patients.
Scyllo-inositol: concentration changes associated with aging and alcohol use, and T2 measurement.
Authors: Deelchand Dinesh , McCarten J. Riley , Hemmy Laura , Auerbach Edward , Eberly Lynn , Marjańska Małgorzata
Published: August 2023

The goals of this study were to investigate the effect of alcohol usage on scyllo-inositol (sIns) in young and older healthy adults, and measure the T2 of sIns in young and older healthy adults. Two brain regions (occipital cortex (OCC), posterior cingulate cortex (PCC)) were studied at 3T. sIns was measured using a short-echo-time STEAM while T2 was measured using LASER. sIns in OCC and PCC regions was found to increase as the brain ages; alcohol usage (0-2 drinks/week) was significantly different between age groups. In addition, there seems to be a trend towards lower T2 of sIns with age.
Microstructural and functional connectivity changes in the locus coeruleus: a 7T study in cognitively impaired subjects
Authors: Jelescu Ileana , Ribaldi Federica , Toussas Konstantin , Costa Sandra da , Jorge Joao , Reynaud Olivier , Frisoni Giovanni , Jovicich Jorge , Pievani Michela
Published: August 2023

The locus coeruleus (LC) is a brainstem nucleus thought to undergo early microstructural and functional connectivity changes in Alzheimer’s disease. The in vivo assessment of LC changes is however limited by the resolution of current 3T MRI systems. Here we used high-resolution high-field diffusion weighted imaging (DWI) and resting-state fMRI in cognitively impaired older persons to investigate diffusion and functional connectivity LC changes, and their association with cognition and connectivity of large-scale networks. Results show reduced diffusivity in the caudal LC and associations between microstructural changes, memory deficits, and lower functional connectivity of the dorsal and ventral attention networks.
Evaluation of Scout Accelerated Motion Estimation and Reduction (SAMER) for measurement of brain volume and cortical thickness
Authors: Lo Wei-Ching , Conklin John , Clifford Bryan , Tian Qiyuan , Polak Daniel , Splitthoff Daniel , Longo‬ ‪Maria Gabriela , Tabari Azadeh , Cauley Stephen , Huang Susie
Published: August 2023

Scout Accelerated Motion Estimation and Reduction (SAMER) is a novel technique that can mitigate motion artifacts in MR images. In this study, we compared the brain volume and cortical thickness measurements obtained from in vivo motion-free, motion corrupted, and motion corrected images acquired with SAMER to those from a motion-free standard MPRAGE reference scan. The quantitative analysis of motion-free and motion corrected SAMER images showed comparable results with motion-free standard MPRAGE.
Pilot-Tone Motion Estimation for Brain Imaging at Ultra-High Field Using FatNav Calibration
Authors: Wilkinson Tom , Brackenier Yannick , Godinez Felipe , Tomi-Tricot Raphael , Sedlacik Jan , Bridgen Philippa , Giles Sharon , Hajnal Joseph , Malik Shaihan
Published: August 2023

3D FatNavs were used to provide a rapid, robust pre-scan to calibrate motion estimation from pilot-tone. The amount of training data required to make reliable forward predictions was investigated. This method robustly predicts motion within a dataset and can be applied to other datasets with lower accuracy. Improving the accuracy and speed of this method is ongoing work. This independent method of motion estimation shows promise for rapid calibration as part of routine examinations and paves the way to offer motion correction at ultra-high field where motion-correction is particularly relevant.
Registration of abdominal DCE-MRI: optimal choice of reference and moving image pairs
Authors: Tattersall Adam , Goatman Keith , Semple Scott , Kershaw Lucy
Published: August 2023

Before registration can take place, an approach to pairing images must be chosen. We used synthetic data to provide a ground truth to evaluate four approaches to pairing images. Our synthetic data was created using tracer kinetics modelling of abdominal DCE-MRI to create motionless data. Then local distortions were applied to the motionless data. We found that using one image as a reference image produced the best result to eliminate the propagation of errors. The reference image must have a similar intensity distribution to the other images in the sequence.
MR-Class: MR Image Classification using one-vs-all Deep Convolutional Neural Network
Authors: Salome Patrick , Sforazzini Francesco , Kudak Andreas , Dostal Matthias , Bougatf Nina , Debus Jürgen , Abdollahi Amir , Knoll Maximilian
Published: August 2023

MR-Class is a deep learning-based MR image classification tool that facilitates and speeds up the initialization of big data MR-based research studies by providing fast, robust, and quality-assured MR image classifications. It was observed in this study that corrupt and misleading DICOM metadata could lead to a misclassification of about 10%. Therefore, in a field where independent datasets are frequently needed for study validations, MR-Class can eliminate the cumbrousness of data cohorts curation and sorting. This can greatly impact researchers interested in big data multiparametric MRI studies and thus contribute to the faster deployment of clinical artificial intelligence applications.
Deep Learning with Perceptual Loss Enables Super-Resolution in 7T Diffusion Images of the Human Brain
Authors: Lohr David , Reiter Theresa , Schreiber Laura
Published: August 2023

Diffusion weighted imaging has become a key imaging modality for the assessment of brain connectivity as well as the structural integrity, but the method is limited by low SNR and long scan times. In this study we demonstrate that AI models trained on a moderate number of publicly available 7T datasets (n=12) are able to enhance image resolutions in diffusion MRI up to 25 times. The applied NoGAN model performs well for smaller resolution enhancements (4- and 9-fold), but generates "hyper" realistic images for higher enhancements (16- and 25-fold). Models trained using perceptual loss seem to avoid this limitation.
Subject classification based on functional connectivity and white matter microstructure in a rat model of Alzheimer’s using machine learning
Authors: Diao Yujian , Pereira Catarina Tristão , Yin Ting , Jelescu Ileana
Published: August 2023

Impaired brain glucose consumption is a possible trigger of Alzheimer’s disease (AD). Previous work revealed affected brain structure and function by insulin resistance in terms of functional connectivity and white matter microstructure in a rat model of AD. Here, functional and structural metrics were further used to classify Alzheimer’s from control rats using logistic regression. Our study highlights the MRI-derived biomarkers that best discriminate Alzheimer’s vs control rats early in the course of the disease, with potential translation to human AD.
3D brain MRI synthesis utilizing 2D SPADE-GAN and 3D CNN architecture
Authors: Ayaz Aymen , de Jong Ronald , Abbasi-Sureshjani Samaneh , Amirrajab Sina , Lorenz Cristian , Weese Juergen , Breeuwer Marcel
Published: August 2023

We propose a method to synthesize 3D consistent brain MRI utilizing multiple 2D conditional SPatially-Adaptive (DE)normalization (SPADE) GANs to preserve the spatial information of patient-specific brain anatomy and a 3D CNN based network to improve the image consistency in all directions in a cost-efficient manner. Three individual 2D SPADE-GAN networks are trained across the axial, sagittal and coronal slice directions and their outputs are thereafter used further to train a CNN based 3D image restoration network to combine them into one 3D volume, using real MRI as a reference. The resulting predicted-synthesized 3D brain MRI is evaluated quantitatively and qualitatively.
Advanced diffusion-weighted MRI and proteomic analysis as potential predictors of renal tumor histopathology
Authors: Bane Octavia , Daza Jorge , Salome Berengere , Sfakianos John , Charap Andrew , Meilika Kirolos , Okhawere Kennedy , Horowitz Amir , Taouli Bachir , Badani Ketan , Lewis Sara
Published: August 2023

In this prospective, single-center study, we evaluated the use of intravoxel incoherent motion model of diffusion (IVIM-DWI) and high-throughput urine proteomics associated with inflammation for diagnosis and characterization of small renal masses. IVIM-DWI parameters had good to excellent diagnostic performance in identifying clear-cell renal cell carcinomas (ccRCC), as well as in distinguishing between stages of ccRCC. In a subset of patients with IVIM-DWI and proteomics, we observed significant correlations between IVIM and proteomic analytes which had differential expression between ccRCC and non-ccRCC, and are involved in promoting the recruitment, expansion and activation of innate and adaptive immune cells.
Erwin - a quantitative MRI toolbox
Authors: Lamy Julien , Mondino Mary , de Sousa Paulo Loureiro
Published: August 2023

Erwin is an open-source Python toolbox dedicated to the computation of quantitative maps from MRI data. It provides a unified interface, through either its Python API or its command-line tool, to well-known qMRI methods (e.g. B1 mapping using Actual Flip Angle (AFI) or T1 mapping using Variable Flip Angle (VFA)) and external toolboxes (e.g. MRtrix or MEDI). Erwin also provides tools to create complex pipelines where the dependencies between steps are tracked: a change in a source image or a method parameter will only trigger the recomputation of a minimal set of subsequent steps.
Quantitative Susceptibility Mapping (QSM) Using High-resolution Ultra-Short Echo Time (UTE) MRI with Rosette k-space Pattern
Authors: Karnik Aparna , Shen Xin , Monsivais Humberto , Sunjar Antonia , Özen Ali Caglar , Ilbey Serhat , Chiew Mark , Cakmak Mukerrem , Rispoli Joseph , Emir Uzay
Published: August 2023

We developed a method of acquiring high-resolution MRI for the generation of Quantitative Susceptibility Mapping (QSM) using Ultra-short echo time (UTE) MRI with a novel 3D rosette k-space trajectory. This method was used to generate high-resolution (0.94 mm3 isotropic) magnetic susceptibility maps in an Iron-Chloride phantom and the human brain. Generated maps were then compared with the susceptibility maps reconstructed from low-resolution data acquired using multi-echo UTE acquisition. Susceptibility values were comparable with current literature demonstrating the promise of this novel method in the generation of QSM.
Highly sensitive “off/on” EPR probes to monitor enzymatic activity by OMRI
Authors: Crich Simonetta Geninatti , Elkhanoufi Sabrina , Alberti Diego , Thiaudiere Eric , Stefania Rachele , Parzy Elodie , Mellet Philippe , Massot Philippe , Aime Silvio
Published: August 2023

New stable organic radicals probes have been proposed in this study to perform Molecular Imaging by monitoring by Overhauser Magnetic Resonance Imaging (OMRI) the enzymatic activity. The radicals used are Tempo-containing esters forming stable micelles that are practically EPR silent. The hydrolysis of the ester bond catalyzed by Carboxyl esterases generates a narrow and intense EPR signal as a consequence of the release of the nitroxide radical from the micelle. Thus we have prepared a off/on probe responsive to the carboxylesterase activity that can be detected quantitatively in the OMR image.
Detection of the Multiple Sclerosis Drug Siponimod Using Fluorine-19 Magnetic Resonance Imaging
Authors: Starke Ludger , Aravina Mariya , Millward Jason , Niendorf Thoralf , Waiczies Sonia
Published: August 2023

Siponimod is a fluorinated drug approved for treatment of secondary progressive multiple sclerosis. We detect 19F-MR signal in the liver, brain, kidneys, and thymus, and achieve the first 19F-MR images of a disease modifying drug, both in the liver and brain ex vivo and in a proof-of-concept in vivo experiment. Clear concentration differences between lobes of the liver or regions of the CNS can be observed. We have demonstrated the feasibility of using 19F-MRI to study the distribution of disease modifying drugs and improve our understanding of pharmacokinetics or guide therapeutic decisions.
Simultaneous molecular 68Ga-PRDG2 and perfusion PET-MR imaging in a patient with sickle cell disease
Authors: Moon Chan Hong , Anderson Carolyn , Tavakoli Sina , Pham Tiffany , Perkins Lydia , Little-Ihrig Lynda , Mason Neal , Chen Xiaoyuan , Laymon Charles , Gladwin Mark , Novelli Enrico
Published: August 2023

Sickle cell disease (SCD) causes vaso-occlusion, ischemia, and end-organ infarction that causes acute pain episodes, also known as vaso-occlusive crises (VOC). Understanding the mechanism underlying VOC is critical to identify patients at risk and for accurate diagnosis while in VOC. PET imaging with the probe 68Ga-PRGD2 that binds integrin αvβ3 identified areas of increased binding of sickle RBC to the endothelium in VOC. Simultaneous PET-MR imaging could provide additional information on tissue changes associated with VOC. Thus, we imaged a patient with SCD with 68Ga-PRGD2 in combination with MRI by using PET-MR 3T scanner.
A Calibration and Compensation Method for Dynamic Range Recovery of Low-Power SiGe Pre-Amplifiers.
Authors: Vassos Christopher , Robb Fraser , Vasanawala Shreyas , Pauly John , Scott Greig
Published: August 2023

Power consumption reduction is key when exploring wireless MRI arrays. An alternative low-power (5.7mW) SiGe pre-amplifier is presented and its impact on imaging performance evaluated in a benchtop setting. The reduction in power results in a more extreme non-linearity that introduces distortion into the images. It is possible to calibrate and compensate for this distortion through receive-only methods. Applying this compensation to the distorted images results in a restoration of image quality with resulting RMSE comparable to industry standard amplifiers representing a potential power reduction up to 30x.
Wireless Power Harvesting of the B1 Field During MR Image Acquisition for Pulse Charging of MR-Compatible Batteries
Authors: Cuthbertson Jonathan , Truong Trong-Kha , Robb Fraser , Song Allen , Darnell Dean
Published: August 2023

A 4-channel power harvesting coil array was developed to allow the energy emitted from RF transmit pulses within the scanner bore during imaging to be converted into DC voltage pulses for recharging MR-compatible batteries, regardless of the scan parameters or imaging pulse sequence. Proof-of-concept experiments in a phantom show that this power harvesting coil array was able to provide energy to a battery during GRE image acquisition for various flip angles and additionally during GRE-EPI, DTI, and MPRAGE image acquisitions.
Mitigation of RF-induced heating on realistic deep brain stimulator lead trajectories by wireless sensor Q-matrix and parallel transmission
Authors: Silemek Berk , Seifert Frank , Brühl Rüdiger , Guerin Bastien , Montag Reiner , Ittermann Bernd , Winter Lukas
Published: August 2023

Measurement-based pTx mitigations on realistic DBS lead trajectories are presented based on small, embedded sensors in the implant casing. Sensor Q-matrix measurements are performed and transmitted wirelessly from the implant to the pTx console. Three different DBS implant trajectories at four different locations have been tested showing successful pTx mitigations of RF induced heating in in-vitro. The methodology is conceptually appealing to be investigated further towards a safety strategy, where an implant communicates with a pTx capable MR scanner in order to improve MR safety and MR imaging performance.
Evaluation of a new, openly accessible in vivo MP2RAGE mouse brain template for registration and morphometric analysis
Authors: Kim Eugene , MacNicol Eilidh , Sreedharan Jemeen , Cash Diana
Published: August 2023

The most popular mouse brain templates are created from ex vivo scans while in vivo templates are not widely available. We have released openly accessible in vivo multi-contrast mouse brain templates and associated tissue probability maps for analyses of in vivo mouse neuroimaging data. Deformation-based morphometry was performed on a test dataset using a study-specific template, our new “MouseIn” template, or the ex vivo DSURQE template. The results using the MouseIn template better matched those using the “gold-standard” study-specific template compared to those using the ex vivo template.
Assessing the feasibility of measuring glycine with a TE-Averaged MRS sequence at 3 Tesla
Authors: Taylor Reggie
Published: August 2023

A TE-Averaged sequence was created on a Siemens Biograph mMR 3 Tesla scanner for the purpose of detecting glycine at a clinical field strength in a healthy population. The sequence demonstrated that it can detect glycine and glutamate with moderate reproducibility, potentially providing a method to indirectly measure the health of the NMDA receptor
Fast scan downfield MR spectra of human brain in vivo at 7.0 Tesla
Authors: Nanga Ravi Prakash Reddy , Elliott Mark , Wilson Neil , Swago Sophia , Witschey Walter , Reddy Ravinder
Published: August 2023

In this study, we investigated the optimal acquisition parameters in terms of voxel size, SNR and total scan time to obtain high quality NAD+ 1H downfield (>4.7 ppm) spectra from human brain at 7 Tesla. Using a spectrally selective excitation spatially selective localization pulse sequence and without water suppression, large voxel size and shorter TR, we were able to acquire NAD+ spectra with an SNR of ~30 in about 5 min. Preliminary results of high SNR and resolution enhanced NAD+ spectra from human brain of healthy volunteers are presented.
A concurrent tDCS-MEGA PRESS MRS study to investigate polarity dependent effects on neurometabolites
Authors: Nagarajan Rajakumar , Shinde Anant , Gunduz Muhammed , Schlaug Gottfried
Published: August 2023

Up- or downregulation of neurotransmitter/receptor concentration have been seen when transcranial direct current stimulation (tDCS) and proton Magnetic Resonance Spectroscopy (MRS) were combined in concurrent experiments; however, results have been mixed and not reliable across studies. In this study, we investigated dose and polarity effects of tDCS in an MRS voxel centered over the anterior cingulate/prefrontal region using three dose levels of tDCS with stimulation electrode placed over left a supraorbital area and return electrode over right mastoid bone. Dose and polarity dependent modulation of GABA and Glx was observed in a single subject study.
Different approaches of aspartate approximation in MEGA-PRESS 1H MRS spectra
Authors: Bulanov Petr , Menshchikov Petr , Manzhurtsev Andrei , Yakovlev Alexey , Akhadov Tolib , Edden Richard , Semenova Natalia
Published: August 2023

Changes in Aspartate (Asp) concentrations are a potential biomarker of malate-aspartate shuttle dysfunction, as well as disturbances in the synthesis of NAA. J-difference editing allows the detection of a resolved Asp signal at δAsp ≈ 2.71ppm. This resonance has a complex shape and therefore approximation of the Asp signal is a challenging task. In our study we compare the performance of six Asp-approximation models applied to data from three brain regions (anterior cingulate gyrus (ACC), dorsolateral pre-frontal area (DLPFA) and visual cortex (VC)). A model consisting of four Gauss signals shows the best performance for all brain regions studied.
Conduction velocity mapping a transcallosal pathway through a correlative multimodal structure-function relationship
Authors: Skoven Christian , Andersson Mariam , Pizzolato Marco , Pakkenberg Bente , Siebner Hartwig , Dyrby Tim
Published: August 2023

The structure-function relationship of axons within the intact brain proves challenging to delineate. We recorded transcallosal conduction time in the rat brain with optogenetics and electrophysiology, estimated pathway length with tractography, - and axon diameters (AD) with dw-MRI and transmission electron microscopy. The modalities exhibit different sensitivity profiles. Recorded latencies correspond only to smaller axons below the mode of the distribution of ADs from histology. dw-MRI is only sensitive to larger axons, not accounted for by electrophysiology and only sparsely with histology. Future correlative studies should choose modalities with a sufficient sensitivity profile for the structural or functional metric of interest.
T1 Weighted Postmortem MR Imaging of the Cerebellum at 3T: Preliminary Results between Feasibility and Desire
Authors: Weigel Matthias , Galbusera Riccardo , Dechent Peter , Bahn Erik , Nair Govind , Kappos Ludwig , Brück Wolfgang , Stadelmann Christine , Granziera Cristina
Published: August 2023

MRI of the fixed human brain is highly interesting, since it basically allows very long scan times for unprecedented MRI resolutions on clinical scanners. Recent work utilized T2* weighted RF spoiled gradient echo sequences to achieve isotropic resolutions up to 160-microns at 3T. This work establishes a T1 weighted MR imaging protocol based on RF spoiled gradient echo sequences that currently enables isotropic resolutions of 240-microns at 3T and depicts the complex fine structure of the fixed cerebellum very well.
Phenotyping a Mouse Model of TRAPPC9 Associated Intellectual Disability with High Resolution MRI and Diffusion Tensor Imaging
Authors: Platt Mark , Plagge Antonius , Poptani Harish
Published: August 2023

Microcephaly and intellectual disability is associated with mutation of the TRAPPC9 gene. A knockout mouse model of TRAPPC9-associated intellectual disability and microcephaly was characterised using high resolution T1 and T2 weighted Magnetic Resonance Imaging (MRI) and Diffusion Tensor Imaging (DTI) alongside behavioural assays. Behavioural differences suggested learning impairment in the model, MRI elucidated the developmental timeline of the disorder and highlighted several brain regions with reduced volume. DTI revealed reduced structural integrity in the corpus callosum.
Diagnosis of Schizophrenia, Bipolar, and Attention Deficit Hyperactivity Disorders using Graph-Theory Features of Resting-State fMRI
Authors: Ghasemi Faezeh , Tavakoli Hosna , Masoudnia Saeed , Tabatabaei Narges Hoseini , Rostami Reza , Nazem-Zadeh Mohammad-Reza
Published: August 2023

Accurate and specific diagnosis of mental disorders is very important for effective, customized, and personalized treatments, which would be made more possible based on individual neuroimaging data. In this study, we classified schizophrenia (SZ), bipolar disorder (BD), and attention deficit hyperactivity disorder (ADHD) cohorts, vs. healthy control (HC) cohort, using extracted graph features from Resting-State fMRI (rs-fMRI) images. The graph-based connectivity features of limbic, auditory, visual, and default mode networks were identified as the most separating features for the SZ, BD and, ADHD groups from the HC group among brain networks.
Aberrant Dynamic Functional Network Connectivity in Adult Patients With Autism Spectrum Disorder
Authors: Yue Xipeng , Bai Yan , Zhang Ge , Shen Yu , Zhang Xianchang , Wang* Meiyun
Published: August 2023

Conventional static functional connectivity analysis does not capture transient and atypical changes in functional connectivity between neural networks in the autism spectrum disorder (ASD) patients. In this study, we evaluated rsfMRI data of 108 adult ASD patients by dynamic functional network connectivity (dFNC) analysis using sliding time window correlation and K-means clustering methods. Our results showed that higher dwell time and altered functional connectivity between multiple nodes in FNC state 2 correlated with clinical ASD scores. Therefore, our study demonstrates that aberrant and transient functional connectivity changes between neural networks in ASD patients can be evaluated by dFNC analysis.
Machine learning-based texture analysis of IVIM-DKI for classification of benign and malignant pancreatic masses
Authors: Malagi Archana , Shivaji Sivachander , Kandasamy Devasenathipathy , Garg Pramod , Gupta Siddhartha , Gamanagatti Shivanand , Sharma Raju , Mehndiratta Amit
Published: August 2023

Tumor heterogeneity could be detected non-invasively utilizing textural indicators from IVIM-DKI, which have a high potential for early prognosis of pancreatic lesions. A novel technique was investigated for tumor prediction model utilizing IVIM-DKI with total variation penalty function, in which we employed combinations of texture characteristics from IVIM-DKI parameters. In this study, texture characteristics of the kurtosis(k) parameter had the high accuracy:93% and AUC:1, and combinations of all IVIM-DKI parameters' textural features after feature reduction had accuracy:84% and AUC:0.91 for classifying benign and malignant pancreatic lesions. Whole-volumetric texture analysis of IVIM-DKI can be employed for characterization of pancreatic lesions.
Pancreatic iron is a marker of cardiovascular complications in sickle cell disease
Authors: Meloni Antonella , Pistoia Laura , Missere Massimiliano , Righi Riccardo , Vallone Antonino , Riva Ada , Positano Vincenzo , Rigoli Luciana , Massei Francesco , Carrai Valentina , Alberini Gianna , Cademartiri Filippo , Pepe Alessia
Published: August 2023

We systematically explored the link between pancreatic iron detected by the T2* Magnetic Resonance Imaging technique and cardiovascular complications in a cohort of 63 patients with sickle cell disease (SCD). Patients with cardiovascular complications (supraventricular arrhythmias, heart failure, pulmonary hypertension, myocardial infarction, deep vein thrombosis, leg ulcers) showed significantly lower global pancreas T2* values than patients free of cardiovascular complications but comparable global heart T2* values. Pancreatic iron overload (T2*<26 ms) was associated with 7.5 times higher odds of cardiovascular complications.
Quantification of The Comb Sign in Crohn’s Disease Using Time of Flight Magnetic Resonance Angiography
Authors: Naim Iyad , Hoad Caroline , Moran Gordon , Gowland Penny
Published: August 2023

Crohn’s disease (CD) is an inflammatory bowel disease affecting 115k people in the UK. The ‘Comb Sign’ describes increased vascularity and arborization of vessels in the mesentery, due to intestinal inflammation. Radiologists observe this sign on cross-sectional imaging as an indication for CD, but it has never been quantified. We used time of flight MR angiography to visualize the vessels in the abdomen without using contrast agents. Images were analyzed using in-house developed software that traces vessels and counts branching points. Scans from 15 healthy volunteers(HV) and 6 CD patients showed patients had more vessel branching points compared to HV.
The feasibility of DCE-MRI in presurgical evaluation of tumor budding grade in rectal cancer
Authors: Hu Wenjun , Chen Anliang , Dong Wan , Li Xiwei , Wang Yue , Liu Yuhui , Liu Ailian
Published: August 2023

Tumor budding (TB) is a histopathologic characteristic which has led to a growing interest in the prognosis prediction of cancers of various sites. Preoperative prediction of TB status may help personalize treatment in rectal cancer cancer patients. Previous studies showed MRI-based and PET/CT based radiomics can predict TB status, however, the high cost and complex post-processing limit their clinical applications. Dynamic contrast-enhanced (DCE) MRI has been extensively evaluated aggressiveness of rectal cancer. Results of this study indicate Kep values can effectively differentiate high from intermediate-low grade TB.
Systemic metabolic dysregulation common across multiple organs
caused by cancer and cancer-induced cachexia
Authors: Sharma Raj Kumar , Bharti Santosh K. , Winnard Paul , Penet Marie-France , Bhujwalla Zaver
Published: August 2023

Analysis of organ metabolism with cancer growth can unravel systemic changes that occur with cancer and with cancer-induced cachexia. Cancer-induced cachexia, commonly observed with pancreatic cancer, causes tissue wasting, intolerance to chemotherapy, and poor quality of life. Here, we identified alterations of metabolic pathways in the spleen, liver, pancreas, lung, heart, brain and kidney following growth of cachexia-inducing and non-cachexia inducing pancreatic cancer xenografts. These results highlight the systemic metabolic changes that occur with cancer and with cancer induced cachexia that may lead to the development of organ-based early biomarkers as well to organ-based metabolic treatment strategies.
Assessment of microstructural changes associated with dyskinesia in hemiparkinsonian rodents
Authors: Bergamino Maurizio , Fuentes Alberto , Marmion David , Sandoval Ivette , Bishop Christopher , Manfredsson Fredric , Stokes Ashley
Published: August 2023

The objective of this pilot study was to assess white matter (WM) microstructural integrity in pre-clinical models of Parkinson’s disease using fractional anisotropy (FA) from diffusion tensor imaging (DTI). We assessed changes in FA in parkinsonian rats with levodopa-induced dyskinesia both over time and compared with control (sham) rats.
Increased liver stiffness and shortened T2* relaxation time in people with type 2 diabetes
Authors: Kupriyanova Yuliya , Bobrov Pavel , Burkart Volker , Schrauwen-Hinderling Vera , Roden Michael
Published: August 2023

This study shows the value of multiparametric magnetic resonance measurements for detecting the changes in liver tissue due to diabetes mellitus. Liver fat content (determined by mDixon MRI and 1H-MR spectroscopy), T2* relaxation time and liver stiffness were compared in humans with type 1 (T1DM), type 2 diabetes mellitus (T2DM) or normal glucose tolerance (control, CON).
Mild neuroanatomical phenotype in an ALS/FTD mouse model with mutation in C9orf72
Authors: Martins-Bach Aurea , Milioto Carmelo , Spring Shoshana , Carcolé Mireia , Cunningham Thomas , Fisher Elizabeth , Isaacs Adrian , Nieman Brian , Lerch Jason , Miller Karla
Published: August 2023

Mutations in the C9orf72 gene are the most prevalent genetic alteration in ALS/FTD. This study investigates neuroanatomical phenotypes in two C9orf72 knock-in mouse models separately expressing either poly-(PR) or poly-(GR) dipeptide-repeats. Ex-vivo structural MRI (40 μm isotropic resolution) was acquired at 7T. After registration, the deformation fields were used to estimate voxels and region-of-interest volumes for comparison between mutants and wild-type mice. Although neuroanatomical phenotypes have been previously described in C9orf72 patients and other ALS/FTD mouse models, 20-month-old poly-(PR) and poly-(GR) mice presented subtle alterations. Further investigations to assess microstructural and histological changes in these mouse models are in progress.
Precuneus dysconnectivity with heart failure
Authors: Mueller Karsten , Möller Harald , Taskin Birol , Thiel Friederike , Beutner Frank , Teren Andrej , Villringer Arno Arno , Schroeter Matthias
Published: August 2023

Our investigations identified the precuneus as the brain region showing a major involvement in connectivity decline in patients with heart failure. Subsequent seed-based correlation analysis showed decreased putamen connectivity related to decline in cognitive performance. In line with these findings and with current Alzheimer’s Disease models showing precuneus connectivity decline as a key feature of brain degeneration, there might be common underlying mechanisms leading to brain connectivity decrease in heart failure and dementia. This hypothesis would be also supported by specific network centrality alterations between precuneus and widely distributed cortical regions particularly in patients showing reduced cognitive performance.
On the concept of long-range short-wave motion tracking
Authors: Schildknecht Christoph , Prüssmann Klaas
Published: August 2023

Current motion tracking modalities operate either in frequency bands that are also occupied by the MRI scanner or interact heavily with the environment. As an alternative, the frequency band of 1-5 MHz can be utilized for motion tracking and has been demonstrated to deliver high performance. Due to the limited sensitivity at a great distance of current broadband systems, we show in this work how short-wave motion tracking can be done at long ranges, enabling independent and robust motion tracking with fewer geometric constraints and greater ease of use.
Magnetic Resonance Thermometry Motion Compensation during Focused Ultrasound Controlled Hyperthermia in a Small Animal Model
Authors: Wong Suzanne , Wunker Claire , Keunen Ben , Siddiqui Maryam , Piorkowska Karolina , Babichev Yael , Foltz Warren , Gladdy Rebecca , Pichardo Samuel , Waspe Adam , Drake James
Published: August 2023

Magnetic resonance guided high intensity focused ultrasound (MRgHIFU) has gained interest over the past decade due to its ability to administer controlled hyperthermia for localized drug release. One of the main challenges is that MR thermometry is highly susceptible to motion artifacts. A hybrid principal component analysis and projection onto dipole fields motion artifact removal method was applied in real-time during controlled hyperthermia in a murine model using a small-animal MRgHIFU system (Bruker 7T MRI and IGT HIFU). For a target temperature of 40.5°C to be maintained, a significant increase in ultrasound power was required when tissue motion was observed.
Rotation estimation for cloverleaf navigators using a k-space map simulation
Authors: Lambourne Tamsin Edwards , van der Kouwe André , Frost Robert
Published: August 2023

Short <5 ms cloverleaf navigators have been demonstrated for prospective motion correction at a rate of 71 Hz in steady-state FLASH. The original cloverleaf approach required a 12 second k-space mapping pre-scan to reliably deal with out-of-plane rotations. Here we investigate simulation of a k-space map based on a low spatial resolution pre-scan. The approach shows potential for real-time detection of rigid-body rotation in the context of real-time self-correction of the cloverleaf orientation.
3D super-resolution MR elastography of the brain
Authors: Hufnagel Simone , Anders Matthias , Aigner Christoph Stefan , Herthum Helge , Tzschaetzsch Heiko , Schaeffter Tobias , Sack Ingolf , Kolbitsch Christoph
Published: August 2023

MR elastography (MRE) provides valuable quantitative information about the mechanical properties of brain tissues. However, due to SNR limitations, often only low through-plane resolution is possible. We present super-resolution MRE based on multiple stacks of complex 3D wavefields of the brain resulting in elastograms with isotropic (1×1×1) mm3 resolution. The approach was evaluated for the in-vivo brain and showed improved visibility of fine structures while presenting consistent shear wave speed values.
GluCEST in Deep Gray Matter and Adjoining White Matter of pediatric-onset Multiple Sclerosis Brains using a Robust B1-calibration Approach
Authors: Kumar Dushyant , Datta Ritobrato , Bacchus Micky , Soni Narayan , Nanga Ravi , Banwell Brenda , Reddy Ravinder
Published: August 2023

Several proton magnetic resonance spectroscopy (1H-MRS) based studies have reported regional alterations of glutamate metabolism in both acute and chronic multiple sclerosis (MS) pathologies, including in normal appearing white matter and mixed tissues. Despite its well-established capability for detecting altered glutamate metabolism, 1H-MRS is hampered by the low spatial resolution that precludes the measurements from small MS lesions. We demonstrate the feasibility of performing glutamate weighted imaging using chemical exchange saturation transfer with B0- and B1- corrections in pediatric-onset MS subjects. The proposed model for B1-calibration is a major improvement over the phenomenological method previously proposed by our group.
Data-driven B1 non-uniformity correction in ultra-high-field small-animal macromolecular proton fraction and R1 mapping
Authors: Yarnykh Vasily , Kisel Alena , Akulov Andrey , Drobyshevsky Alexander
Published: August 2023

The data-driven surrogate B1 field correction algorithm was recently developed to eliminate B1-related spatial errors in the macromolecular proton fraction (MPF) and R1 maps obtained using the fast single-point method. The algorithm obviates the need for acquisition of actual B1 field maps, thus extending the routine use of fast MPF mapping. Initially, the surrogate B1 correction was applied to the human brain imaging at 3T. In this study, the method has been adopted and validated for small-animal imaging utilizing dedicated ultra-high-field MRI scanners. Particularly, we report guidelines on using surrogate B1 field correction in 9.4T and 11.7T magnetic fields.
comprehenCEST: a clinically feasible CEST protocol to cover all existing CEST preparations
Authors: Kamm Lukas , Herz Kai , Sedykh Maria , Fabian Moritz , Zaiss Moritz
Published: August 2023

In a clinical setting, it often has to be decided, which CEST sequences to pick of a collection, due to measurement time limitations. Therefore, eventually not all of the desired contrasts can be measured. In this work, we comprehensively combine seven CEST protocols in a single measurement, use a fast single-shot 3D gradient echo readout and remove redundant regions of the experimental parameter space. Hereby, we can half the total measurement time from 35 to 17 minutes. With further parameter reduction, a total measurement time of 10 minutes is conceivable. This allows to design powerful hypothesis generating clinical pilot studies.
Optimization of pH-Weighted Contrasts in the Spinal Cord using Chemical Exchange Saturation Transfer (CEST) MRI
Authors: Cronin Alicia , Liebig Patrick , Detombe Sarah , Duggal Neil , Bartha Robert
Published: August 2023

Degenerative cervical myelopathy (DCM) is a degenerative disease of the spine that leads to compression and neurological dysfunction. Recovery after surgery can be impacted by hypoxia in the cord, however the magnitude of this effect is currently unknown. Chemical Exchange Saturation Transfer (CEST) can produce contrast related to tissue pH, an indicator of hypoxia, but the method works best at ultra-high fields. Performing CEST in the spinal cord is also complicated by respiratory and cardiac motion and cerebrospinal fluid flow. The purpose of this work was to optimize pH-weighted CEST imaging in the human spinal cord at 3 Tesla.
Quantitative imaging of gene therapy delivery vehicles using CEST-NMR/MRI
Authors: Lam Bonnie , Velasquez Mark , Velasquez-Mao Aaron , Godines Kevin , AlGhuraibawi Wissam , Vandsburger Moriel
Published: August 2023

We hypothesized that AAV2 capsids may generate endogenous CEST contrast similar to LRP. We tested this using NMR CEST under varying pH, density, biological transduction stage, across serotypes and mixed biological media. Subsequent experiments determined the pH-dependent exchange rate and optimized CEST saturation schemes for AAV contrast detection at 7T. The results of this study reveal that AAV capsids generate endogenous CEST contrast around 0.6-0.8ppm. Exchangeable protons are likely from serine and threonine residues on the AAV capsid. Based on calculated fast exchange rates, an optimized CEST saturation scheme generated robust CEST contrast in mixed biological media phantoms at 7T.