bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency sweep 31P MR spectroscopic imaging at 7T
Authors: Lim Songi , Widmaier Mark , Xin Lijing
Published: August 2023

Phase-cycled spectroscopic imaging (PCSI) method was implemented and validated for 31P PCSI imaging at 7T. The PCSI method uses a balanced steady-state free precession sequence with an ultra-low flip angle (<1°) to achieve sharp passband with 2.52-ms of TR, which enable to accelerate the acquisition. With prior knowledge of 31P spectra, it is feasible to acquire major 31P peaks by changing the frequency offset and non-uniform phase sweeping instead of acquiring full spectra uniformly. To investigate feasibility of the method, a multi-compartment KH2PO4 phantom with in vivo equivalent concentrations was prepared and 31P PCSI was compared with conventional FID-CSI.
Quality Assurance and Quality Control for HRMAS MRS Studies of Human Blood
Authors: Cheng Leo , Sanchez-Dahl Matteo , Muti Isabella , Weng JianXiang , Zhong Anya
Published: August 2023

The lack of a standard universal protocol for sample preparation in MRS experiments results in instrumental and biological variability across reported studies. The purpose of this experiment is to evaluate a quality assurance protocol for performing HRMAS 1H MRS experiments with human biofluid samples, such as blood serum. The research objective is to determine if the spectral results measured from pooled samples can be used to assess results from individual samples as controls. These findings will help better develop efficient standard protocols for researchers and clinicians to use in the future.
Coil to Coil: Self-supervised denoising using phased-array coil images
Authors: Park Juhyung , Park Dongwon , Shin Hyeong-Geol , Choi Eun-Jung , Shin Dongmyung , Chun Se Yong , Lee Jongho
Published: August 2023

A self-supervised learning framework, Coil to Coil (C2C), is proposed. This method generates two noise-corrupted images from single phased-array coil data to train a denoising network and, therefore, requires no clean image nor acquisition of a pair of noisy images. The two images are processed to have the same signals and independent noises, satisfying conditions for the noise to noise algorithm, which requires paired noise-corrupted images. C2C shows the best performance among popular self-supervised denoising methods in both real and synthetic noised images, revealing little or no structure in the noise map.
Deep Learning-Based Receiver Coil Sensitivity Map Estimation for SENSE Reconstruction using Transfer Learning
Authors: Arshad Madiha , Qureshi Mahmood , Inam Omair , Omer Hammad
Published: August 2023

Many Parallel MRI algorithms (e.g. Sensitivity Encoding (SENSE)) require knowledge of the receiver coil sensitivity maps. Magnetic field strength is an important factor in defining the sensitivity maps of the receiver coils in MRI. This paper presents a method to estimate the receiver coil sensitivity maps of a higher magnetic field strength scanner utilizing a deep learning network (denoted as ResU-Net-34), initially trained on the receiver coil sensitivity maps of a lower field strength scanner using transfer learning. SENSE reconstruction results show a successful domain transfer between the receiver coil sensitivities of different magnetic field strengths with the proposed method.
Applying advanced denoisers to enhance highly undersampled MRI reconstruction under plug-and-play ADMM framework
Authors: Yan Kang , Wang Zhixing , Dou Quan , Chen Sheng , Meyer Craig
Published: August 2023

Accelerating MRI acquisition is always in high demand, since long scan time can increase the potential risk of image degradation caused by patient motion. Generally, MRI reconstruction at higher undersampling rates requires regularization terms, such as wavelet transformation and total variation transformation. This work investigates employing the plug-and-play (PnP) ADMM framework to reconstruct highly undersampled MRI k-space data with three different denoiser algorithms: block matching and 3D filtering (BM3D), weighted nuclear norm minimization (WNNM) and residual learning of deep CNN (DnCNN). The results show that these three PnP-based methods outperform current regularization methods.
Sampling Pattern Optimization for Joint Acceleration of Multi-contrast MRI using Deep Learning
Authors: Seo Sunghun , Luu Huan Minh , Choi Seung Hong , Park Sung-Hong
Published: August 2023

Usage of multiple-acquisition MRI is one field of study that proved its effectiveness and practicality since routine MR scan protocol typically acquires multiple information for the same anatomical structures. In this study, we propose simultaneous optimization of sampling pattern and reconstruction for joint acceleration of multi-contrast MRI. The simultaneous optimization of sampling pattern and reconstruction provided superior performance over single contrast imaging and over single sampling pattern for multi-contrast MRI. The proposed technique can be adopted in routine clinical scan without forcing extra scans during acquisition.
129Xe MRI patterns of lung function in patients with asthma and/or COPD in the NOVELTY study
Authors: Marshall Helen , Smith Laurie , Biancardi Alberto , Collier Guilhem , Chan Ho-Fung , Hughes Paul , Brook Martin , Astley Joshua , Munro Ryan , Rajaram Smitha , Swift Andrew , Capener David , Bray Jody , Hussain Ayla , Ball James , Rodgers Olly , Jakymelen Demi , Smith Ian , Tahir Bilal , Rao Madhwesha , Norquay Graham , Weatherley Nick , Armstrong Leanne , Hardaker Latife , Fihn-Wikander Titti , Blé François-Xavier , Hughes Rod , Wild Jim
Published: August 2023

There is a need for biomarkers to guide appropriate treatment in patients with clinical features of both asthma and COPD. A broadly-defined population of 164 patients with asthma and/or COPD taking part in the NOVELTY study were recruited from primary care and scanned with 129Xe MRI (ventilation, acinar microstructure and gas exchange measurements). 129Xe MRI global and regional metrics showed significant differences between patients with asthma, asthma+COPD and COPD. 129Xe MRI metrics remained sensitive to diagnosis sub-groups when only patients with normal pulmonary function tests were considered.
Flip-angle map calculation via keyhole reconstruction in uniform and variable-density 2D-spiral hyperpolarized 129Xe MRI
Authors: Plummer Joseph , Bdaiwi Abdullah , Costa Mariah , Willmering Matthew , Cleveland Zackary , Walkup Laura
Published: August 2023

Hyperpolarized 129Xe-MRI is prone to B1-inhomogeneity-induced signal artifacts, that often obscure pulmonary abnormalities. B1-inhomeogeneity can be corrected by calculating a flip-angle map and rescaling the images. Current methods to acquire a flip-angle map in 2D-spiral sequences require two-successive images to be collected in a single breath-hold, doubling scan duration. We demonstrate that flip-angle maps can be calculated from a single image acquisition using keyhole reconstruction. Furthermore, analytical methods can be used to minimize the amount of required oversampling. This approach enables accurate B1-artifact correction, with minimal impact to scan-duration, making it especially useful for short breath-hold studies.
Dynamic Free-Breathing Ventilation and Gas Exchange with Hyperpolarized Xenon-129
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

Hyperpolarized xenon-129 (HXe) imaging is capable of quantifying lung function through measurements of ventilation and gas exchange. However, traditional HXe approaches rely on long breath-holds for imaging, which may not be representative of steady-state behavior and are limited by the volume of gas that can be delivered. In this work, we imaged gas- and dissolved-phase xenon continuously over approximately 50 breaths and retrospectively binned the images, generating dynamic maps encompassing the entire respiratory cycle.
Hyperpolarized 129Xe Diffusion MRI and Diffusion Morphometry in Mice using 2D Spiral
Authors: Costa Mariah , Albert Brice , Bdaiwi Abdullah , Ediga Harshavardhana , Madala Satish , Niedbalski Peter , Cleveland Zackary
Published: August 2023

Hyperpolarized (HP) 129Xe diffusion imaging, including the apparent diffusion coefficient (ADC) and more sophisticated diffusion morphometry, can assess microstructural dimensions of the acinar airspace. In diseases characterized by alveolar destruction (eg, emphysema), these parameters strongly indicate disease severity. Here, a time-efficient, 2D-spiral diffusion sequence was developed and compared to a conventional GRE-based sequence in a free-diffusion phantom, wild-type mice, a and a transgenic mouse model of lung fibrosis that develops emphysema as a comorbidity. Both sequences provided comparable SNR, ADC values, and morphometry metrics, indicating spiral sequences can assess airspace size in mice, while making efficient use of HP magnetization.
Hyperpolarization of 129Xe gas via dissolution DNP: beneficial tips and tricks
Authors: Wiström Emma , Capozzi Andrea , Lê Thanh Phong , Gruetter Rolf , Hyacinthe Jean-Noël
Published: August 2023

Dissolution DNP (dDNP) is an alternative for hyperpolarizing 129Xe to the well acknowledged method spin exchange optical pumping (SEOP). As opposed to SEOP, DNP takes place in the solid state at very low temperatures. Therefore, it can potentially produce a large volume of hyperpolarized gas after dissolution. In this study, by implementing a new way of preparing the sample, we ease the overall process and establish a superior incorporation of the gas atoms into the solvent. Additionally, due to a surprisingly short radical electron T1, we show that a higher polarization was achieved by applying microwave frequency modulation.
Hyperpolarized 13C imaging at moderate field strengths: SNR considerations and in-vivo feasibility at 1.5T
Authors: Fuetterer Maximilian , Traechtler Julia , Dounas Andreas , Hoh Tobias , Albannay Mohammed , Kozerke Sebastian
Published: August 2023

Motivated by the fact that the hyperpolarized MRI signal does not quadratically scale with field strength as for conventional MRI at thermal equilibrium, the achievable SNR at reduced field strengths is explored. It is demonstrated that for larger coil diameters, sample noise dominates electrical noise at 1.5T and achievable SNR becomes comparable to 3T. By adaptively reducing acquisition bandwidth to the reduced spectral span and given longer T2* decay, effective SNR at 1.5T exceeds 3T. Feasibility is demonstrated with the first in-vivo data acquired on a clinical 1.5T system using hyperpolarized 13C pyruvate.
Towards 15N molecular MRI with 15N-nicotinamide hyperpolarized by dissolution dynamic nuclear polarization (dDNP)
Authors: Peters Josh , Brahms Arne , Janicaud Vivian , Anikeeva Mariia , Peschke Eva , Ellermann Frowin , Ferrari Arianna , Aden Konrad , Schreiber Stefan , Herges Rainer , Hövener Jan-Bernd , Pravdivtsev Andrey
Published: August 2023

We synthesized 1-15N nicotinamide (NA) and built a saddle-shaped mouse body linear coil for 15N imaging. We found a way to polarize 1-15N-NA by dissolution dynamic nuclear polarization to 9.1±4.4% and measured the effect of the radical load. The lifetime of hyperpolarized NA was field-dependent: 100 s at 1 T, 60 s at 7 T, and 30 s at 9.4 T. An effect of the pH on liquid-state polarization was found. N FLASH MRI of hyperpolarized NA was acquired in less than 1 s.
Fast 3D Passive Needle Localization for MR-Guided Interventions using Radial White Marker Acquisitions and CNN Postprocessing
Authors: Faust Jonas , Krafft Axel , Polak Daniel , Vogel Ralf , Speier Peter , Behl Nicolas , Ladd Mark , Maier Florian
Published: August 2023

Accurate 3D localization of biopsy needles during MR-guided interventions is especially challenging due to time restrictions in real-time workflows. While active tracking methods rely on additional RF-sensitive hardware, rapid passive tracking methods often make use of markers or prior knowledge regarding the needle location. In an ex-vivo study, we investigated a novel passive tracking method using heavily undersampled, radial acquisitions in combination with contrast-optimized White Marker imaging and CNN image postprocessing regarding its potential to speed up passive needle artifact localization without the use of additional hardware or prior knowledge on the needle location.
Measurement of magnetic fringe fields from a proton pencil beam scanning nozzle causing MR image ghosting artefacts during in-beam MR imaging
Authors: Semioshkina Ekaterina , Oborn Bradley , Hoffmann Aswin
Published: August 2023

Proton therapy (PT) is expected to benefit from real-time MRI guidance. However, the integration of MRI and PT is challenging due to the interaction between the magnetic fringe fields of the PT beamline and the B0-field of the MR scanner. In this study, we measured the magnetic fringe field of the PT beamline. The measurement data will be used to validate a finite element model. With a match to this model, we can proceed to investigate what type of magnetic shielding solution would be needed to decouple the magnetic fields of the PT and MRI systems.
A new single channel method for electromagnetic interference reduction on a 50 mT permanent magnet system
Authors: Parsa Javad , O'Reilly Thomas , Webb Andrew
Published: August 2023

External electromagnetic interference (EMI) in unshielded low field and portable MRI systems can swamp the signal, and various multi-detector methods have been developed to minimize it. A new EMI cancellation method designed for a single-channel receiver-system has been implemented on a 50 mT system by using the MR-inactive channel of a birdcage coil and a 180o power hybrid. This method results in up to a 97% reduction in the standard deviation of external EMI.
Development of a Low-Cost B0 Field Mapping Device
Authors: Eisenmann Marcel , Fomin Ivan , Prier Marcus , Rose Georg , Speck Oliver
Published: August 2023

Field mapping devices are used to determine the spatial distribution of magnetic fields. As magnetic devices are very unique in shape and size, commercially available mapping devices are often complex and customised and therefore too costly for small-format magnetic resonance imaging (MRI) systems and the open-source community. A low-cost field mapping device with a Hall sensor for the OCRA tabletop MRI system1 is developed. Field maps are measured and compared against a commercial Hall probe. The presented measurements show that the developed device can compete with commercially available devices.
Characterising the Magnetic Field Inhomogeneity for Open MRI at 0.5T using a Screened Coil NMR Probe Design
Authors: Mistry Dipendra , Gowland Penny , Mougin Olivier , Bowtell Richard , Glover Paul
Published: August 2023

Image distortion caused by field inhomogeneity and instability is a major limitation for open MRI systems. Magnetic Field Monitoring (MFM) is a well-documented approach to characterise and thus compensate for these effects using an array of NMR probes. Here a novel NMR probe with a secondary coil is presented, which is designed to protect the pre-amplifier during transmission of a uniform B1 field. Preliminary data has verified this result and temporal variations of the B0 field have been observed. This approach will be developed with multiple probes to measure and compensate for the spatio-temporal response of the system.
Caffeine acutely reduces aqueductal CSF flow in humans
Authors: Kylkilahti Tekla , Wictor Max , Töger Johannes , Bloch Karin Markenroth , Lundgaard Iben
Published: August 2023

In this ultra-high field 7T MRI study, we find that caffeine acutely reduces CSF net flow in humans. Interestingly, regular caffeine consumption seems to be protective against this reduction. We used non-invasive 2D PC 7T MRI in healthy volunteers to measure CSF flow in the cerebral aqueduct. Ventricular CSF flow is upstream of the glymphatic system and may thus reflect or affect the function of CSF-mediated clearance pathways that have been suggested to be important for waste product removal in the brain. Better understanding of CSF dynamics may help us find new targets for treating proteinopathies such as Alzheimer’s disease.
Changes in cerebrospinal fluid dynamics and its coupling with global brain activity in early glaucoma patients
Authors: Bang Ji Won , Yarsky Eva , Wollstein Gadi , Schuman Joel , Chan Kevin
Published: August 2023

Neurodegenerative diseases are thought to involve changes in the cerebrospinal fluid (CSF). Since glaucoma is a neurodegenerative disease of the visual system, here, we examined the CSF dynamics in glaucoma patients. Specifically, using resting-state fMRI, we observed that early glaucoma patients present greater power in the low frequency of the CSF flow and greater coupling between CSF flow and global brain activity compared to late glaucoma patients. Further, the coupling between CSF flow and global brain activity is associated with the volumes of the optic nerve and optic chiasm. Overall, our results suggest that glaucoma involves changes in CSF flow.
Implementation of non-invasive Filter-Exchange Imaging (FEXI) to measure blood-brain barrier water exchange in the rat brain
Authors: Ohene Yolanda , Powell Elizabeth , Lasič Samo , Parker Geoff , Parkes Laura , Dickie Ben
Published: August 2023

We have developed a preclinical FEXI sequence optimised to measure water exchange across the blood-brain barrier in the rat brain. Simulated synthetic data estimated an apparent exchange rate (AXR) of 1.22 s-1, using the in-vivo acquisition parameters and exchange rate constant = 2.5 s-1, reflecting in-vivo measurements. The experimental normalised AXR in the rat brain was measured at 3.34 ± 1.14 s-1 (scan) and 3.62 ± 0.96 s-1 (rescan), with CoV = 26%, n = 10. This technique is a promising non-invasive tool which can be applied to in a wide range of disease models, including neurodegeneration, stroke and neuroinflammation.
Improved visualization of intracranial peripheral arteries with multiple 2D slice ASL-MRA and super-resolution
Authors: Suzuki Yuriko , Jezzard Peter , Koktzoglou Ioannis , Okell Thomas
Published: August 2023

In recent years, magnetic resonance angiography (MRA) using arterial spin labeling (ASL) technique has been developed aiming to be a non-invasive potential alternative to X-ray angiography. When blood flow is slow (e.g. in elderly patients, especially with steno-occlusive diseases), however, ASL-MRA suffers from poor vessel visualization, which hinders its clinical utility in those patients. In this study, instead of using a 3D volume acquisition commonly used in brain MRI, we propose to separately scan multiple 2D slices to reduce the saturation of arterial blood signal and improve the visualization of small peripheral arteries, in combination with a super-resolution reconstruction.
Cerebrovascular brain-age
Authors: Dijsselhof M.B.J. , Barboure M. , Stritt M. , Nordhøy W. , Wink A.M. , Westlye L.T. , Cole J.H. , Barkhof F. , Petr J. , Mutsaerts H.J.M.M.
Published: August 2023

The structural brain-age makes predictions based on changes in tissue integrity. Adding cerebrovascular MRI biomarkers may add sensitivity to physiological and metabolic changes, hence complementing structural brain-age, and possibly improving its early pathology sensitivity. Baseline and follow-up T1w, FLAIR, and ASL data of 233 healthy participants and combinations of features and algorithms were used to predict ‘Cerebrovascular brain-age’.

The ExtraTrees algorithm utilising T1w, ASL, and FLAIR features performed best and showed good longitudinal reproducibility.
Novel arterial spin labelling (ASL) brain injury symmetry assessment in retired professional athletes: a preliminary study
Authors: Danielli Ethan , Padrela Beatriz , Doughty Mitchell , Petr Jan , Mutsaerts Henk , Noseworthy Michael
Published: August 2023

3D PCASL scans were acquired for seventeen aging, retired professional football players with a history of head traumas. Left, right and bilateral CBF and ASL spatial coefficient of variation (sCoV) values were examined for twelve concussion-related ROIs. A Z-scoring approach was applied, with outliers defined as mild, moderate, or severe injury burden (IB). An IB symmetry index was also calculated. Outliers were detected in all 12 ROIs, and the anterior parahippocampal gyrus and inferior frontal gyrus pars opercularis had the highest CBF and ASL sCoV IB, respectively. IB was not biased towards the left or right hemisphere.
Quantitative functional brain mapping imaging using Arterial Spin Labelling for safe neurosurgery
Authors: Iannotti Giannina , Nadin Isaure , Tourdot Quentin , Momjian Shahan , Schaller Karl , Lovblad Karl , Grouiller Frédéric
Published: August 2023

Brain functional mapping is fundamental in pre-surgical workflow to target areas to be preserved. This work aims at validating ASL as alternative to BOLD to map eloquent cortex, by offering a quantitative measure of the perfusion associated to neuronal activity. Thirty healthy subjects underwent TMS motor mapping and executed a clenching-motor-task in a 3T-MR-scanner, while ASL and BOLD volumes were acquired simultaneously. The comparison between the global maxima of BOLD and ASL activations revealed that ASL localizes significantly deeper and more anteriorly than BOLD. ASL global maximum was found closer than BOLD to the most representative point of TMS mapping.
Wall shear stress in abdominal aortic aneurysms: a 4D Flow MRI case-control study
Authors: Trenti Chiara , Ziegler Magnus , Bjarnegård Niclas , Ebbers Tino , Lindenberger Marcus , Dyverfeldt Petter
Published: August 2023

Current guidelines for risk stratification of abdominal aortic aneurysm are based on vessel diameter and are not sufficient to prevent catastrophic events. Wall shear stress based parameters (WSS, OSI and RRT) are potential markers for AAA altered hemodynamics. Here, WSS vectors were computed from 4D flow MRI in the whole aorta of patients with AAA, age-matched elderly controls, and young normal controls. The aorta was divided in five segments and average values were computed in each segment. AAA had lower WSS and higher RRT in the IAA compared to proximal segments and to the age-matched controls, but not higher OSI.
Imaging of aortic valve dynamics: comparison between sub-millisecond MRI and echocardiography
Authors: Scotti Alessandro , Luo Qingfei , Zhong Zheng , Nazir Noreen T , Xie Karen , Zhou Xiaohong Joe
Published: August 2023

The aortic valve dynamics is traditionally examined using ultrasound echocardiography in clinical practice. Recently, a novel MRI technique capable of sub-millisecond temporal resolution, coined get-SPEEDI MRI, was successfully applied to visualize the aortic valve dynamics. We have evaluated both get-SPEEDI and echocardiography on healthy human subjects and found a substantial agreement between both techniques in the characterization of the aortic valve opening and closing phases. The sub-millisecond temporal resolution of get-SPEEDI allows for the measurement of steep AVA variations and the visualization of detailed features that may reflect the cardiac function and physiology.
Resting-state functional connectivity differences in preterm and term born children at school age
Authors: Jeong Hyejin , Cho Hye Jung , Shim So-Yeon , Park Chan-A
Published: August 2023

Children born preterm are at a significant risk of neurodevelopmental impairment. Alterations of functional connectivity in higher-order association cortices after preterm birth might reflect cognitive or behavior problems in school-aged children born preterm. Our results will help understanding the pathophysiology of cognitive and behavior development in children born preterm without apparent brain injury or major neurodevelopmental impairment.
Individualised assessment of regional brain volumes in neonates with Down syndrome reveals extreme deviation in white matter and cerebellum.
Authors: Gartner Abi Fukami - , Baburamani Ana , Dimitrova Ralica , Patkee Prachi , Alfageme Olatz Ojinaga - , Bonthrone Alexandra , Uus Alena , Hughes Emer , Deprez Maria , Counsell Serena , Hajnal Joseph , Edwards A. David , O’Muircheartaigh Jonathan , Rutherford Mary
Published: August 2023

There are relatively few early neuroimaging studies of Down syndrome (DS), despite being the most common genetic cause of intellectual disability, with characteristics present from birth. The aim of this study was to conduct a group-level analysis of volumetric differences across multiple brain regions in neonates with DS (n = 20) using individual z-scores extracted from robust normative modelling of typically developing neonatal controls (TDC; n = 493). In addition to well-documented cerebellar hypoplasia, here we have identified that neonates with DS have markedly reduced volumes in the cingulate, frontal, insular and occipital WM segments compared to TDC.
Neonatal seizures induce significant changes in cerebral oxidative metabolism
Authors: Sierhej Agnieszka , Bainbridge Alan , Kendall Giles , Sokolska Magdalena , Pegoretti-Baruteau Kelly , Rennie Janet , Mathieson Sean , Robertson Nicola , Boylan Geraldine , Mitra Subhabrata
Published: August 2023

Neonatal seizures are common following neonatal encephalopathy and have the potential for themselves to cause further brain injury. Data were collected from 55 term neonates who underwent therapeutic hypothermia following neonatal encephalopathy. 25 developed seizures. Magnetic resonance Spectroscopy showed that in the seizure group, lactate was increased and Naa and Choline were decreased. Lower tNaa in neonates with seizures likely indicates further neuronal injury and may explain seizure induced neurological deficits
Noise reduction in fractional anisotropy maps using deep learning based denoising
Authors: Bhat Seema , Poojar Pavan , Padma Chennagiri , MC Hanumantharaju
Published: August 2023

Denoising is an alternative for enhancing signal-to-noise ratio in high b-value diffusion imaging instead of prolonged acquisition time. We experimented a deep learning based denoising method on prospective high b-value DWI and visualized the impact of denoising using fractional anisotropy(FA) maps. Experiment was repeated for three different signal averages:1,2 4-NEX and two different slice thickness 1mm and 5mm with gold standard reference of 10-NEX images. The current work obtained average peak signal-to-noise ratio >34dB and SSIM >0.94 after denoising for FA maps. The PSNR and SSIM values in FA maps were modestly increased after denoising.
MRCP at 1.5 T: comparing image quality and acquisition time between respiratory-triggered and breath-hold SPACE sequences
Authors: Li Xin , Qin Yue , Jin Dayong , Zhu Yinhu , Liu Liyao , Qian Yifan , Tian Juan , Wang Shaoyu
Published: August 2023

This study used magnetic resonance cholangiopancreatography (MRCP) to compare the image quality and acquisition time of conventional respiratory-triggered (RT), modified RT, and breath-hold (BH) sampling perfection with application-optimized contrasts using different flip evolutions (SPACE) sequences in patients with biliary and pancreatic disorders. Our results suggested that modified RT-SPACE-MRCP sequence can significantly reduced acquisition time and had better image quality. The MRCP sequence can be selected flexibly according to the patient's situation to obtain good diagnostic images.
Quantifying metabolites in large brain areas by 3D Echo Planar Spectroscopic Imaging spectral averaging for a study of cigarette smoking
Authors: Alger Jeffry , Diaz Maylen Perez , O'Neill Joseph , Ghahremani Dara , Dean Andy , Sheriff Sulaiman , Maudsley Andrew , London Edythe
Published: August 2023

Spectral averaging of thousands of magnetic resonance spectroscopic imaging voxel spectra over large brain volumes provides a means of assessing low-level and/or hard-to-quantify metabolite differences over large brain volumes between groups of individuals.
Determinants of MR Relaxation in the Extremely Preterm Brain at Adolescence: Myelin and Iron
Authors: McNaughton Ryan , Hua Ning , Zhang Lei , Kennedy David , O'Shea T. , Kuban Karl , Jara Hernan
Published: August 2023

Purpose: To describe the dependencies of multiparametric quantitative MRI (MP-qMRI) on myelin and iron content in the extremely preterm born brain at adolescence. Methods: Algorithms for a fast exchange relaxation (FER) model and MP-qMRI create maps of R1, R2, myelin, and iron in 30 participants using MR images obtained with the triple TSE pulse sequence at age 15 years. Results: R1 and R2 have linear dependencies with myelin and iron content, respectively. Conclusion: Application of a FER model produces coregistered maps of myelin and iron content which exhibit unique influences on the relaxation of white matter and gray matter regions.
Improved ΔR2* calculation through voxelwise subtraction for MRI-based dosimetry of holmium-166 transarterial radioembolization
Authors: van Wijk Meike , Roosen Joey , Gotby Lovisa Westlund , Arntz Mark , Janssen Marcel , Lobeek Daphne , van de Maat Gerrit , Overduin Christiaan , Nijsen J. Frank
Published: August 2023

Transarterial radioembolization (TARE) is a treatment for liver cancer, during which radioactive microspheres are administered through the hepatic artery. Microspheres containing holmium-166 enable MRI-based dosimetry, based on subtraction of pre- and post-treatment $$$R_2^*$$$ values. This subtraction is performed using a mean pre-treatment $$$R_2^*$$$ value. This does however not take pre-existing differences of $$$R_2^*$$$ values into account, introducing an error in the dosimetry. In this work a voxelwise subtraction method is presented, using deformable registration to transform the pre-treatment $$$R_2^*$$$ map to the post-treatment $$$R_2^*$$$ map, enabling voxel-by-voxel subtraction. This method does take $$$R_2^*$$$ differences into account and improves MRI-based dosimetry.
Improving T1 mapping with a golden-angle radial MOLLI and a model-based regularized reconstruction SALSA-EPG
Authors: Freitas Andreia C , Gaspar Andreia S , Silva Nuno A , Bioucas-Dias José , Nunes Rita G
Published: August 2023

T1 mapping provides valuable information regarding cardiovascular pathologies. Clinical approach consists of using a Cartesian MOLLI sequence and fitting a 3-parameter model. Although easy and straightforward, this method can require long breath-holds and does not explicitly include other factors affecting T1 estimation. We propose coupling an accelerated golden-angle radial MOLLI with a model-based regularized reconstruction (SALSA). The proposed method was tested in phantom and in vivo data at 1.5T. Improved T1 precision and good accuracy was found for the phantom data. Lower T1 was estimated with SALSA compared to the commercial sequence in vivo, future work will address this.
Quantitative Relaxometry Metrics for Normal and Brain Tumor Tissues using MR Fingerprinting and Magnetic Resonance Image Compilation Methods
Authors: Konar Amaresha Shridhar , Shah Akash , Dave Abhay , Banerjee Suchandrima , Fung Maggie , Hatzoglou Vaios , Shukla-Dave Amita
Published: August 2023

This work aims to assess the relaxometry maps generated using MRF and MAGiC in brain tumor (n=27). A total of 14 brain tumor tissue regions (Pre-Tx n=5, Post-Tx n=9) were used for comparison. The T1 and T2 values measured at tumor and normal appearing (contralateral) region showed significant difference in both MAGiC and MRF generated maps. The results show that the relaxometry values estimated using MRF and MAGiC methods can differentiate Tumor and normal appearing tissues. The utility of this technique needs to be further explored in larger sample studies and it could be further extendable to classify tumor types.
High-resolution T1 atlas for subject-specific abnormality detection at 7T
Authors: Piredda Gian Franco , Radojewski Piotr , Joseph Arun , Bonanno Gabriele , Egger Karl , Yang Shan , Venkategowda Punith , Corredor-Jerez Ricardo , Maréchal Bénédicte , Wiest Roland , Thiran Jean-Philippe , Hilbert Tom , Kober Tobias
Published: August 2023

Previous studies at 3T have shown that T1 relaxometry enables personalized characterization of brain tissues by comparing physical properties of a single patient to a normative atlas. Ultra-high field imaging allows exploiting this concept at even higher resolutions, which can be crucial to detect certain diseases. To this end, here we established an atlas of normative T1 values at 7T from acquisitions with 0.6$$$\times$$$0.6$$$\times$$$0.6 mm3 isotropic resolution. Additionally, the clinical potential and improvement of 7T vs. 3T imaging is shown in two case reports from patients scanned at both field strengths.
Improved spatial normalization of white matter fiber orientation distributions using T1-weighted contrast
Authors: Guerrero-Gonzalez Jose , Surgent Olivia , Adluru Nagesh , Kecskemeti Steven , Kirk Gregory , Dean Douglas , Travers Brittany , Alexander Andrew
Published: August 2023

Fiber orientation distributions (FOD) derived from diffusion magnetic resonance imaging (dMRI) enable resolution of multiple fiber populations within a voxel. FOD-based white matter studies include voxel-based analysis, atlas-based labeling, and group average fiber tracking. These methods require spatial normalization of the FODs. This work describes an alternative approach for FOD spatial normalization based on co-registering individual dMRI to the T1-weighted (T1w) images, non-linear spatial normalization of the T1w images to a template, and applying the transformations to the FOD maps. This approach is compared to the conventional approach of directly aligning FOD maps.
End-to-End Scan Parameter Optimization for Improved Myelin Water Imaging
Authors: Whitaker Steven , Nielsen Jon-Fredrik , Fessler Jeffrey
Published: August 2023

Optimization techniques can be used to design scan parameters for quantitative imaging. The Cramér-Rao Lower Bound (CRLB) is often used for such designs, but it only characterizes unbiased estimators. We propose an end-to-end approach to scan design that optimizes scan parameters with a particular estimator in mind. We compare CRLB-based and end-to-end scan designs in the context of myelin water imaging. The end-to-end scan design results in lower estimation error in simulation and an in vivo myelin water fraction (MWF) map with improved contrast. The proposed end-to-end scan design approach is thus a promising alternative to using the CRLB.
Correction of CSF Partial Volume Bias in 23Na Magnetic Resonance Fingerprinting
Authors: Kratzer Fabian , Flassbeck Sebastian , Schmitter Sebastian , Wilferth Tobias , Bachert Peter , Ladd Mark , Nagel Armin
Published: August 2023

This work investigates the bias in the quantified relaxation times due to partial volume contributions of CSF for 23Na magnetic resonance fingerprinting (MRF) and reference methods. In simulations, a CSF contribution of only 10% resulted in an overestimation of 17% (31%) in T2l* in brain tissue for MRF (the reference). Further, a simple approach for CSF bias correction for 23Na MRF is proposed. This reduced the average absolute T1 deviation in brain tissue from 15% to 4%. The deviation in T2l* (T2s*) was reduced from 17% (35%) to 9% (5%). Finally, the correction was applied to in vivo MRF data.
Repeatability of simultaneous 3D 1H MRF/23Na MRI in brain at 7T
Authors: Rodriguez Gonzalo , Yu Zidan , O'Donnell Lauren , Calderon Liz , Cloos Martijn , Madelin Guillaume
Published: August 2023

In this work, we assess the repeatability of proton density, T1, T2 and sodium density maps measured with simultaneous 3D 1H MRF/23Na MRI in the brain at 7T. We scanned seven healthy subjects three times each. The coefficients of variation (CV) were in the range 1-3% for mean values in GM, WM and CSF, and the intra-class correlation (ICC) was in range 0.44-0.99.
Multi-nuclear 1H/23Na Sodium MRI reveals relationship between intermuscular adipose tissue and tissue sodium content
Authors: Pridmore Michael , Gamboa Jorge , Ormseth Michelle , Oeser Annette , Stein C. Michael , Crescenzi Rachelle
Published: August 2023

Adipose tissue depositions between muscle compartments, known as intermuscular adipose tissue (IMAT), occurs in various conditions such as with obesity and aging. Tissue sodium content (TSC) measured by sodium magnetic resonance imaging increases with aging and may be associated with insulin resistance. In this study, we found a correlation between IMAT volume percentage and muscle TSC (r=0.52, p=0.01). Additionally, mean TSC in the IMAT region was higher than mean TSC in total muscle (p<0.001). The relationship between tissue sodium content and IMAT opens avenues for understanding the mechanisms of sodium storage and fat depositions in tissue compartments of the leg.
Towards standardising quantification in 23Na-MRI by synthetic polyacrylamide gel phantoms
Authors: Rot Samuel , Oliver-Taylor Aaron , Golay Xavier , Solanky Bhavana , Wheeler-Kingshott Claudia Gandini
Published: August 2023

Accuracy in quantitative 23Na (sodium) MRI is impacted by the quality of the signal calibration phantom. Agarose phantoms, the current benchmark, exhibit various unfavourable qualities. To move towards standardisation in 23Na-MRI, the objective was to develop a synthetic, polymer-based calibration phantom for traceable, reliable and accurate quantification in 23Na-MRI. Crosslinked polyacrylamide gel (PAG) was selected as the most suitable choice, for its bi-exponential 23Na T2 decay. Here, we present the T1, T2 properties and 23Na-MRI data of prototype PAG phantoms at different 23Na concentrations. PAG emerges as a reliable choice to replace the ubiquitous agarose gel phantom.
Evaluation of 23Na relaxation times and concentrations in the patellar knee cartilage at 3T
Authors: Kamp Benedikt , Frenken Miriam , Henke Jan , Abrar Daniel , Nagel Armin , Gast Lena , Oeltzschner Georg , Wilms Lena , Nebelung Sven , Antoch Gerald , Wittsack Hans-Jörg , Müller-Lutz Anja
Published: August 2023

23Na relaxation times and concentrations were measured in patellar cartilage with a clinical 3T MRI scanner. Because of the low resolution in 23Na imaging, a focus was set on reducing the influence of synovial fluid. To estimate T1 a biexponential two-compartment fitting model was applied. In T2* measurements, an inversion pulse was used to suppress the signal from synovial fluid. 23Na parameters were successfully determined and are in good accordance to literature results measured at higher field strengths.
An iterative algorithm for resolving high-resolution 23Na Multi-Quantum Coherences MRI from prior 1H constraints
Authors: Licht Christian , Schad Lothar R. , Rapacchi Stanislas
Published: August 2023

Sodium (23Na) MRI offers great potentials to be a clinical marker for disease states. Besides the single quantum signal, the triple quantum signal of 23Na could provide novel and complementary information. 3D volumetric 23Na multi-quantum coherences imaging, however, suffers from poor signal-to-noise ratios, which limit spatial resolution. Finer structures such as tissue boundaries are therefore barely observable. In addition, partial volume effects become more severe and diminish image quality as well as diagnostic applicability. The purpose of this work is to develop a reconstruction framework that addresses these shortcomings of 23Na multi-quantum coherences imaging by utilizing 1H prior constraints.
Fast 23Na-T2* relaxation parameter estimation in the human brain
Authors: Riemer Frank , Reisert Marco , Solanky Bhavana , Wheeler-Kingshott Claudia , Xavier Golay , Grüner Renate , Maximov Ivan
Published: August 2023

Due to quadrupolar interactions, 23Na exhibits a bi-exponential T2. Previous approaches to estimate T2* have relied on simple least squares approaches or treating it as an inverse problem. Here we present a fast method based on Bayesian estimation and illustrate it on an in vivo dataset.
Feasibility study of novel 8-channel stacked 1H/31P transceiver coil as PET insert for 7T MRI
Authors: Forner Ria , Branderhorst Woutjan , Rivera Debra , Raaijmakers Alexander , Welting Dimitri , Klomp Dennis
Published: August 2023

The feasibility of simultaneous 1H/31P PET/MR imaging added-on to an existing 7T MRI system was assessed. Space constraints preclude using whole-body birdcages. Instead, an 8-channel 1H dipole array stacked with additional 8-31P channels is set up. By positioning PET detectors between the RF-shield and gradient coil, further shielding of the PET-crystals and electronics can be omitted. 8-channel 31P scans had a higher SNR compared to a birdcage setup. The 1H/31P setup gives ~5% degradation of PET sensitivity. Similarly, the impact of the new setup (proximity of the RF shield) was insignificant for MRI performance at both frequencies.
Age Dependent Changes of Water Exchange Rate in Blood Brain Barrier (BBB) Assessed by Diffusion-Prepared Arterial Spin Labeling
Authors: Shou Qinyang , Shao Xingfeng , Felix Kimberly , Ojogho Brandon , Jiang Xuejuan , Herting Megan , Wang Danny
Published: August 2023

The purpose of this study was to investigate the relationship between water exchange rate (kw) of blood brain barrier and age. Diffusion Prepared pCASL technique was used to measure kw in four datasets with a wide range of age (8 to 81 years). Global and regional kw values as well as cerebral blood flow and arterial transit time were analyzed. The results show an overall trend of decreasing kw with age, in parietal and parahippocampal regions there are U-shaped and inverted U-shaped changes of kw with age.
Measurement of CSF pulsation from EPI-based human fMRI
Authors: Kim Jun-Hee , Im Jae-Geun , Park Sung-Hong
Published: August 2023

To study CSF dynamics and brain functional activity simultaneously with quantitative aspect, we proposed a new method for quantifying CSF pulsatility information based on an interslice CSF pulsation model in 4th ventricle of EPI-based fMRI (CSFpulse). The proposed CSFpulse successfully detected the higher CSF flow during the resting state than the typical task states, both in quantitative and time course aspects. Also, CSFpulse was significantly correlated with stroke volume measured using phase contrast MRI during functional states. Based on these results, CSFpulse can be used for investigating functional changes in BOLD and CSF pulsation simultaneously based on conventional EPI-based fMRI.
Early post gadolinium T2-W FLAIR signal intensity change in normal brain tissues and CSF: significance for clinical neuroimaging and neurofluids
Authors: Agarwal Nivedita , Peruzzo Denis , Port John , Carare Roxana , Bydder Graeme
Published: August 2023

Apart from the study of meningeal diseases, cortical metastases and multiple sclerosis, T2-W FLAIR is used for analyzing the CSF drainage of fluids. However, little is known regarding gadolinium induced signal intensity (SI) changes in the normal gray (GM) and white matter (WM). The SI ratios GM/WM and CSF/WM increase by 2.5% and 7% respectively whereas the SI in WM does not change. These findings are important for the interpretation of clinical findings and will provide better understanding of the movement of neurofluids in the human brain at early time points (e.g.4-5 minutes after GBCA injection).
Pulmonary transit time derived from routine perfusion cardiac magnetic resonance scans for non-invasive assessment of hemodynamics
Authors: Segeroth Martin , Winkel David , Yang Shan , Sauter Alexander , Bremerich Jens , Zellweger Michael , Müller Christian , Haaf Philip
Published: August 2023

Pulmonary transit time (PTT) derived from routine cardiac magnetic resonance perfusion scans is a robust and easily obtainable noninvasive parameter of hemodynamics. PTT correlates with both LVEF, RVEF and NT-proBNP and could serve as a new global non-invasive parameter with a discriminative character for detecting cardiopulmonary dysfunction. We demonstrate that PTT has a high diagnostic accuracy in terms of exclusion and inclusion of heart failure as assessed by NT-proBNP, even in patients with preserved LVEF and RVEF.
Assessment of myocardium native T1 and perfusion using exercise CMR with a novel MRI-compatible supine ergometer
Authors: He Bo , Gao Fabao
Published: August 2023

This study investigated the feasibility of a novel compact MRI-compatible ergometer to evaluate myocardial tissue characteristics and blood flow. The results showed a significant increase in heart rate, RPP, native T1 and MBF by using this ergometer in healthy controls. Our study has shown an excellent reproducibility in measuring free-breathing native myocardial T1, MBF and MPR during exercise. The pilot testing demonstrated that the novel compact MRI-compatible ergometer was successful at inducing a cardiac stress state and can able to characterise exercise physiology at every stage allowing high quality MR imaging during the stress.
Perfusion system for studying dynamic metabolomics in rat brain slices exposed to oxygen and glucose deprivation using 1H and 31P NMR
Authors: Hill Deborah , Molska Alicja , Andreassen Trygve , Widerøe Marius
Published: August 2023

We designed an NMR-compatible bioreactor that allows real-time metabolic measurements of viable rat brain slices under normal conditions and under conditions mimicking hypoxic-ischemic (HI) brain injury. Special emphasis was put on providing physiological temperature in the system, a significant factor in the HI model. 1H NMR spectra were acquired to assess changes in brain metabolites. Peaks of lactic acid, NAA, glutamate, aspartate, and creatine were detected. By acquiring a time series of proton spectra, we observed significantly increased lactate levels over time when switching from normoxia to hypoxia while other metabolites remained stable over the whole experiment.
Towards non-invasive assessment of cardiovascular physiology by combining cardiac MRI with predictive biomechanical modeling
Authors: Waugh Rebecca , Gusseva Maria , Greil Gerald , Chapelle Dominique , Hussain Tarique , Chabiniok Radomir
Published: August 2023

Biomechanical models coupled with cardiovascular MRI (CMR) have the potential to provide non-invasively physiological parameters of clinical interest. The approach is presented and validated on a group of 10 patients who underwent CMR and invasive catheterization. Patient-specific models are built based on CMR data and maximum/minimum arterial pressure. The stroke work, derived from ventricular pressure-volume (P-V) loops, was comparable between the measured and simulated P-V loops, suggesting the high quality of the in silico loops. An excellent correlation of the model-derived myocardial contractility with maximum time-derivative of ventricular pressure gives an opportunity for the non-invasive characterization of patients’ inotropic state.
A simplified method to estimate blood flow velocity and inversion efficiency in the major cerebral arteries using multi-PLD pCASL
Authors: Allery Freya , Bulte Daniel , Hocking Embla , Blockley Nicholas , Harkin James , Pinto Joana
Published: August 2023

ASL inversion efficiency is often assumed as a pre-defined value or estimated by acquiring an additional phase-contrast MR image. While the former approach might be inaccurate in certain conditions, the latter can be time-consuming. Here, we propose a simplified method that estimates blood flow velocity and inversion efficiency solely using the ASL data. This novel strategy was tested using multi-PLD pCASL datasets with two different blood flow dynamics (normo- and hypercapnia). Our results show the feasibility of this approach and highlight the need for subject/condition-specific inversion efficiency estimation for a more accurate quantification of CBF.
Specific Quantification of Myelin by QSM and MWI: Comparison to DTI in Mouse of Pelizaeus Merzbacher Disease and Metachromatic Leukodystrophy
Authors: Loebel Ulrike , Zhou Lepu , Rune Gabriele , Sereda Michael , Kungel Theresa , Matzner Ullrich , Fiehler Jens , Sedlacik Jan , Bley Annette
Published: August 2023

Two different disease models, i.e., of Pelizaeus Merzbacher disease (PMD) and Metachromatic Leukodystrophy (MLD), were studied in mice using QSM, MWF, MTR and DTI as well as histopathology to assess their ability to specifically quantify myelin damage. Electron microscopy of PMD showed damaged myelin, but histological micrographs of MLD showed regular brain tissue integrity but with an abnormal presence of macrophages. Only MWF and QSM showed a difference between PMD and WT, but no difference between MLD and WT, which suggests, that MWF and QSM are highly specific to myelin damage.