bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Singular-Value Shrinkage for fMRI Denoising
Authors: Shahdloo Mo , Chiew Mark
Published: August 2023

Singular-value truncation techniques have shown promise for reducing thermal noise in fMRI, where singular-values below a certain threshold are assumed to be noise and are discarded. However, this approach could lead to suboptimal signal recovery, since the remaining singular-values could still have variance contributed by noise. Here instead we propose to use a theoretically MSE-optimal function to shrink the remaining singular-values. The proposed method is evaluated using simulations and high-resolution in-vivo human brain data, and is shown to improve signal-to-noise ratio and functional statistics while leaving the spatial precision intact.
Accelerated 3D stack-of-spiral bSSFP for functional imaging at 9.4T: Pilot study
Authors: Valsala Praveen Iyyappan , Ehses Philipp , Veldmann Marten , Scheffler Klaus
Published: August 2023

We investigate the possibility of using longer multi-shot spiral readouts to accelerate balanced steady-state free precession (bSSFP) at ultra-high field (UHF) for functional imaging. The reconstruction is performed with the full signal model accounting for spatial B0 inhomogeneity and gradient imperfections. We present the activation maps from flickering checkerboard stimulus experiment and discuss challenges of spiral bSSFP at UHF.
VASO fMRI USING 2D-SMS SPIRAL READOUTS
Authors: Kurban Denizhan , Huber Renzo , Liberman Gilad , Ivanov Dimo , Poser Benedikt A
Published: August 2023

High-resolution blood volume-sensitive fMRI VASO can capture functional signal changes with high localization specivity compared to conventional BOLD sequences. However, it suffers from reduced sampling efficiencies and lower detection sensitivity. Here, we overcome these limitations by combining VASO contrasts with the high efficiency of multi-echo enabled spiral k-space sampling and CAIPI-optimized SMS acceleration. We find that spiral sampling enables faster VASO acquisitions than possible with Cartesian EPI sampling. For high spatial resolutions (1.25mm), we confirm that the proposed method is insensitive to large draining veins while having more stable fMRI signals (higher tSNR).
3D super-resolution motion-corrected cardiac T1 mapping
Authors: Hufnagel Simone , Metzner Selma , Aigner Christoph Stefan , Schulz-Menger Jeanette , Schaeffter Tobias , Kolbitsch Christoph
Published: August 2023

Cardiac T1 mapping provides valuable quantitative information about fibrosis in various cardiac diseases. Due to SNR limitations and the motion of the heart during imaging, often 2D T1 Maps with only low through-plane resolution (i.e. slice thickness of 6-8 mm) can be obtained. We present a model-based super-resolution reconstruction which combines multiple stacks of 2D acquisitions with 6 mm slice thickness and generates 3D high-resolution T1 maps. Cardiac and residual respiratory motion is corrected for. The approach was evaluated in native T1 mapping in three healthy volunteers and provided precise T1 maps with improved visualization of small structures.
Translating 3D Whole Heart LGE to Clinical Practice; Early Feasibility Results in a Tertiary UK Centre
Authors: Jathanna Nikesh , Strachan Kevin , Erhayiem Bara , Jamil-Copley Shahnaz
Published: August 2023

Accurately identifying left ventricular fibrosis is paramount for diagnostic, prognostic and procedural reasons. Increasing evidence for the benefit of 3D whole heart imaging in fibrosis identification is emerging. Limitations to integrating 3D whole heart imaging into routine practice include risking suboptimal imaging incumbering diagnostic value. We undertook retrospective quantitative and qualitative analysis of clinically indicated paired 2D and 3D imaging. Quantitative SNRscar and CNRscar-myo analysis was not significantly different and qualitative diagnostic utility was comparable both in patients with ischaemic and non-ischaemic disease. This small study provides evidence for routine usage of 3D whole heart imaging for scar identification.
White matter hyperintensities and their dynamic nature: diffusion MRI analysis of white matter hyperintensity regression
Authors: Jochems Angela , Maniega Susana Muñoz , Clancy Una , Garcia Daniela Jaime , Wiseman Stewart , Blair Gordon , Brown Rosalind , Backhouse Ellen , Arteaga Carmen , Hewins Will , Sakka Eleni , Kampaite Agniete , Stringer Michael , Thrippleton Michael , Bastin Mark , Hernández Maria Valdés , Marshall Ian , Doubal Fergus , Wardlaw Joanna
Published: August 2023

White matter hyperintensities (WMH) have been shown to progress over time but they might regress too. Little is known about the regression of WMH as the main focus has been on progression. We investigate WMH regression and their dynamic properties using diffusion MRI. Areas of WMH change, both progression and regression, might have different tissue integrity properties than areas that are more stable, i.e. stable normal-appearing white matter (NAWM), become more hyperintense, or stable WMH. Mean diffusivity and peak width of skeletonized mean diffusivity (PSMD) might be most sensitive to subtle integrity changes before they become visible on structural MRI.
DTI-defined structural integrity metrics of the functionally-defined dentatothalamocortical pathway are related to disability
Authors: Chen Jacqueline , Nemani Ajay , Huang Xuemei , Li Xin , O'Laughlin Kyle , Plow Ela , Baker Kenneth , Lowe Mark , Jones Stephen , Machado Andre
Published: August 2023

Prior to the implantation of brain stimulating electrodes, it would be valuable to have an estimation of the severity of pre-existing injury to the pathways of interest. In chronic stroke patients, we used resting-state functional MRI and transcranial magnetic stimulation (TMS) to identify functionally connected regions of the dentatothalamocortical pathway. We found that diffusion tensor imaging metrics of the tract connecting thalamus to the hand-motor hotspot were significantly correlated with hand function. These results suggest that this non-invasive functional/structural MRI/TMS approach can provide pathway-specific injury metrics that may be useful as part of a pre-surgical evaluation.
Characterizing Brain Structural Differences in Hemodialysis Patients using MAP MRI
Authors: Richerson Wesley , Schmit Brian , Wolfgram Dawn
Published: August 2023

We collected brain MRI data using a custom, advanced diffusion sequence as well as typical T1 and T2 FLAIR anatomical images to characterize the differences between controls and Hemodialysis (HD) patients in a pilot study. We found decreased gray matter volume and thickness as well as increased white matter hyperintensity lesion volume in HD patients. Using the Mean Apparent Propagator technique, we found increased gray and white matter mean square displacement, white matter q space inverse variance and return to plane probability.
Quantitative Susceptibility Mapping and R2* Mapping Suggest Demyelination in Silent Cerebral Infarcts in Sickle Cell Anaemia
Authors: Murdoch Russell , Stotesbury Hanne , Kawadler Jamie , Saunders Dawn , Kirkham Fenella , Shmueli Karin
Published: August 2023

To investigate the composition of silent cerebral infarcts (SCI) in sickle cell anaemia (SCA), we compared the magnetic susceptibility (χ) and transverse relaxation rates (R2*) of segmented SCI lesions to normal appearing white matter (NAWM) in the contralateral hemisphere. In 37 SCA subjects and 8 healthy controls (HC), SCI lesions were significantly less diamagnetic and had significantly lower R2* relative to NAWM. The χ and R2* changes indicate demyelination within the lesions. R2* mapping suggests that SCI lesions are more demyelinated in the SCA subjects, relative to HC, likely due to the haemodynamic challenges associated with the condition.
Neurogenic metabolites after intravenous autologous stem cells infusion in Stroke: a high resolution NMR spectroscopic analysis of human sera
Authors: Bhasin Ashu , Kumar Pawan , Kumaran S Senthil , Mewar Sujeet , Srivastava MV Padma
Published: August 2023

High resolution NMR spectroscopy to study the neural and cellular metabolites from serum samples of 14 chronic stroke patients after autologous bone marrow derived mononuclear stem cells and neurorehabilitation using 700 MHz NMR spectrometer. The data were processed using the Agilent software, Vnmrj2.3A. PLS-DA multivariate analysis was performed to explore biochemical shifts and upregulation between patients with stem cell infusion and controls. Using MetaboAnalyst (3.0) software, we observed elevated levels of myoinositol, choline, NAA, ML in one group 1 as compared to group 2 (groups undisclosed).
Impact of diffusion tractography tracking parameters and smoothing polynomial order on muscle fiber measurements
Authors: Lockard Carly , Hooijmans Melissa , Zhou Xingyu , Damon Bruce
Published: August 2023

Diffusion-tensor MRI tractography has been applied to characterize muscle diffusion properties and architecture. Tract propagation is performed using various propagation algorithms, settings, and step sizes. Smoothing, such as by polynomial fitting, has been shown to reduce tract path errors due to noise. Optimal settings for tracking algorithm, parameters, and order of subsequent smoothing polynomials have not been established. This work examines the effect of tracking algorithm settings, step size, and polynomial order on muscle architecture and diffusion estimates and polynomial fit residuals behavior. Results emphasize the high sensitivity of curvature estimates to smoothing polynomial order.
A spectrally interleaved magnetic resonance spectroscopic imaging sequence incorporating semi-adiabatic pulses at ultrahigh field
Authors: Verma Gaurav , Dehkharghani Seena , Alon Leeor , Balchandani Priti
Published: August 2023

A spectrally-interleaved semi-adiabatic magnetic resonance spectroscopic imaging sequence was developed to simultaneously acquire water and metabolite resonances within the same repetition time. A water interleave enables eddy current correction, absolute quantification through water reference and thermometry using empirically-derived formulae based on chemical shifts of temperature-sensitive water and temperature-insensitive metabolites. The sequence successfully acquired both 1-minute single voxel and 4-minute multi-voxel acquisitions in phantom and in vivo, producing temperature estimates of 21.2 °C, and 35.7 °C, respectively. LCModel fitting of metabolites provided reliable fitting of multiple metabolite peaks including separation of glutamate and glutamine.
Comparison of in vivo hepatic metabolic quantitation by localized 31P MRS at 7T
Authors: Pfleger Lorenz , Bogner Wolfgang , Schmid Albrecht Ingo , Scherer Thomas , Wolf Peter , Krebs Michael , Krššák Martin
Published: August 2023

This study focuses on the comparison of different in vivo data-acquisitions for quantifying hepatic 31P metabolite concentrations using a phantom replacement method. We have compared a 1D-slab localized DRESS, a single-voxel-spectroscopy (SVS) ISIS as well as a 3D-CSI 31P MRS acquisition at 7T. Each method has its own advantages and disadvantages and needs to be chosen according to the focus and design of the study.
Postprocessing Reduces Pulsation Artifacts and Increases Visibility of Liver Lesions in Flow-compensated Diffusion-weighted Imaging
Authors: Führes Tobit , Saake Marc , Seuss Hannes , Müller Astrid , Bickelhaupt Sebastian , Stemmer Alto , Benkert Thomas , Uder Michael , Hensel Bernhard , Laun Frederik
Published: August 2023

Diffusion-weighted imaging of the liver is prone to the cardiac pulsation artifact, which can lead to reduced lesion visibility. We addressed this problem with a two-fold approach. First, flow-compensated diffusion weightings were used, which are known to reduce this artifact. Using a dataset of 40 patients suffering from focal liver lesions, we addressed the remaining signal voids with different postprocessing techniques, namely weighted averaging, the p-mean approach, and an outlier exclusion algorithm. The algorithms substantially increased the lesion visibility and further reduced the pulsation artifact. An evaluation of CNR and calculation time showed that weighted averaging was suited best.
Denoising Diffusion MRI with Self-supervised Learning on Coresets via Matrix Sketching
Authors: Fadnavis Shreyas , Chowdhury Agniva , Drineas Petros , Garyfallidis Eleftherios
Published: August 2023

Diffusion MRI typically has a low SNR on account of the noise from a variety of sources corrupting the data. The state-of-the-art denoiser Patch2Self proposed a self-supervised learning technique that uses patches from all the voxels to learn the denoising function which in practice can be resource-intensive. We, therefore, propose Patch2Self2 which performs self-supervised denoising using coresets constructed via matrix sketching, resulting in significant speedups and reduced memory usage. Our results showed that sampling-based sketching via leverage scores gave the best performance. Remarkably, leverage scores can be directly used as a statistic for interpreting influential regions hampering the denoising performance.
Dissolved 129Xe spectroscopy in the lungs of preterm-born children
Authors: Chan Ho-Fung , Collier Guilhem , Smith Laurie , Biancardi Alberto , Bray Jody , Marshall Helen , Hughes Paul , Rao Madhwesha , Norquay Graham , Swift Andrew , Hart Kylie , Cousins Michael , Kotecha Sailesh , Wild Jim
Published: August 2023

Ventilation defects and increased alveolar heterogeneity have been observed previously with 129Xe MRI in preterm-born children. We hypothesised that reduced gas exchange in preterm-born children could be measured with dissolved 129Xe whole lung spectroscopy. The ratio of red blood cells (RBC) to tissue/plasma (TP) signals (RBC/TP) was significantly elevated in the lungs of 34 preterm-born children compared with 16 term-born children. This trend was unexpected and we hypothesise that in preterm-born children a reduced number of alveolar septa due to birth at an early stage of lung development can lead to decreased TP signal and thus increased RBC/TP ratio.
OxyChip embedded with gold nanoparticles as a sensor for EPR oximetry and self-fiducial for anatomic registration
Authors: Kmiec Maciej , Hebert Kendra , Tse Dan , Hodge Sassan , Williams Benjamin , Schaner Philip , Kuppusamy Periannan
Published: August 2023

EPR oximetry using the OxyChip can provide direct and repeated measurement of tissue oxygen; however, a significant limitation is its inability to identify the location of the probe in the tissue. We report the development of an OxyChip embedded with gold nanoparticles to visualize the implant using clinical ultrasound or CT. In vitro characterization, imaging, and histopathology of the probe using tissue phantoms, excised tissues, and in vivo animal models demonstrated a substantial enhancement of CT contrast with OxyChip-GNP without compromising its oxygen-sensing properties or biocompatibility. The OxyChip-GNP can facilitate precisely localized in vivo oxygen measurements in the clinical setting.
Deuterated trityl spin probe for in vivo pO2 imaging with Time-Domain EPR
Authors: Devasahayam Nallathamby , Kishimoto Shun , Chandramouli Gadisetti , Otowa Yasunori , Yamashita Kota , Yamamoto Kazutoshi , Brender Jeffrey , Krishna Murali
Published: August 2023

In this work, we present our first 3D in vivo EPR oximetry study using Ox071 spin probe in comparison with Ox063 oximetry. The R2* change with [Ox071] and pO2 was calibrated using standard solutions. In vivo EPR imaging of a mouse tumor was performed on successive days by using either Ox071 or Ox063. The zero gradient signal level of Ox071 was about twice stronger and lasted almost twice longer compared to Ox063. The spin density, and pO2 maps and pO2 histograms of tumor regions marked by co-registration with MRI were similar between Ox063 and Ox071.
Feasibility of MRI-guided Interventions at a Large-bore New-generation 0.55T Low-Field MRI System
Authors: Khodarahmi Iman , Brinkmann Inge , Bruno Mary , Walczyk Jerzy , Brown Ryan , Fritz Jan
Published: August 2023

New generation low-field MRI systems can be ideal for MRI-guided interventions due to wide bore diameters and lower susceptibility artifacts improving patient access and needle visualization, respectively. We evaluated a set of pulse sequences for their suitability for needle visualization using a new-generation 0.55T system and compared the results with those of a clinical 3T system. Interventional needles can be adequately visualized at 0.55T. Using TSE pulse sequences, needle artifacts display more favorable at 0.55T than 3T. SEMAC and HASTE pulse sequences may not facilitate diagnostic needle visualization at 0.55T but are not needed for clinical MR interventions.
Phase-Based B1 Mapping in a 65 mT Single-Sided Prostate MRI Scanner
Authors: Grissom William , Sadinski Meredith , Nacev Alek , De Matos Gomes Muller
Published: August 2023

B1 mapping is important to characterize non-uniform coil geometries and to optimize imaging sequences and image reconstructions in low-field MRI, but is made challenging by point-of-care single-sided imaging geometries with large frequency bandwidths and B1 ranges. We propose a high-bandwidth phase-based B1 mapping technique based on a CHORUS pulse sequence with alternated frequency sweep polarities, which has a wide (40 kHz) imaging bandwidth and high B1 dynamic range. The sequence was implemented and validated on a 65 mT single-sided prostate MRI scanner in phantom scans with butterfly coil transmit and local multichannel receive.
Type-III NUFFT Image Reconstruction for a 65 mT Single-Sided Prostate MRI Scanner with Non-Linear Gradient Fields
Authors: Sadinski Meredith , Narayanan Ram , Nacev Alek , Grissom William
Published: August 2023

Single-sided low-field MRI scanners can provide image guidance during interventions such as prostate biopsies without restricting surgical access. However, image reconstruction from these scanners is challenging due to the non-linearity of their gradient fields and inhomogeneous B0 fields. At the same time, non-Cartesian sampling is desirable for these scanners to maximize SNR efficiency and provide self-navigation. In this work, we report a fast iterative 3D Type-III NUFFT reconstruction for a 65 mT single-sided prostate imager, with non-linear single-sided gradient fields and a built-in B0 gradient field. The reconstruction was compared with a model-based reconstruction for a high-bandwidth radial RARE acquisition.
Continuous Perfusion Measurement With Singled Sided Low Field MR
Authors: Little Alice , Thomas Dion , Tzeng Shieak , Obruchkov Sergei
Published: August 2023

In this study we focus on exploring the use of a single sided low-field MR systems to continuously measure perfusion. For this purpose we developed a contrast-free measurement technique - tentatively named Inhomogeneous Flow-sensitive Alternating Inversion Recovery (IFAIR). This new technique, adapted from the FAIR ASL protocol, was designed to be suitable for inhomogeneous field conditions and to function without pulsed gradient fields. The IFAIR signal response displayed a consistent proportional relationship to flow velocity, with potential to allow for quantitative flow-dependent measurements.
Cerebrospinal fluid-tissue exchange revealed by phase alternate labeling with null recovery MRI
Authors: Li Anna , Xu Jiadi
Published: August 2023

Our understanding of the CSF exchange with surrounding tissues and its correlation with brain function is limited. We presented the first non-invasive MRI methods to quantify this process with two novel T1 and ADC Phase Alternate LAbeling with Null recovery (PALAN) schemes. The CSF signal was nulled, while the partial recovery of other tissues was labeled by alternating the phase of the pulse by using the significantly different T1 and ADC values between CSF and the other tissues. Rapid and major CSF water exchange occurs on the surface of the ventricles.
Assessment of Choroid Plexus Perfusion and the Blood-CSF Barrier with Multi Post Label Delay Arterial Spin Labeling MRI and Vasodilation
Authors: Zhu Yufei , Zhao Moss , Shen Bin , Zaharchuk Greg , Fan Audrey
Published: August 2023

The choroid plexus contributes to the production of cerebrospinal fluid (CSF), maintains electrolyte and metabolic balance, and plays important immunological roles. Here, we sought to determine whether multi-post label delay (PLD) arterial spin labeling (ASL) MRI could robustly measure cerebral blood flow (CBF) in the choroid plexus and its response to a vasodilatory challenge. We saw choroid plexus perfusion increase by 30 ml/100g/min (p=0.0003) with acetazolamide. We also calculated the ratio of the choroid plexus to anterior ventricle ASL signal (rCV) as a clinically useful biomarker of blood-CSF passage and observed an average increase of 0.529 in rCV post vasodilation.
Using diffusion kurtosis imaging to measure glymphatic system related changes during human sleep
Authors: Örzsik Balázs , Cercignani Mara , Harrison Neil
Published: August 2023

Glymphatic clearance has been associated with an increase in interstitial volume fraction during sleep. Higher order diffusion weighted MRI images were acquired of awake and sleeping participants to investigate glymphatic system related changes. Sleep was associated with a significant decrease in kurtosis measures. Clusters with significant decrease in radial kurtosis were located in default mode network areas, occipital cortex, thalamus, midbrain and temporal lobe. Decrease in kurtosis is in line with the glymphatic system hypothesis, as diffusion becomes more Gaussian when it is less restricted, which expected with the increase in interstitial space volume.
Reproducibility of aortic diameter and displacement derived from free-breathing 3D balanced steady-state free precession CINE images at 3T
Authors: Merton Renske , Schrauben Eric , Strijkers Gustav , Nederveen Aart , van Ooij Pim
Published: August 2023

Capturing 3D aortic motion over the heart cycle may give insight into a new biomarker for aortic disease and potentially improve the measurement of aortic hemodynamic parameters. An isotropic, free-breathing, respiratory-corrected 3D CINE balanced steady-state free precession imaging technique of the thoracic aorta was developed to investigate scan-rescan reproducibility of aortic diameter and displacement measures in nine healthy volunteers. Scan-rescan diameter was highly reproducible (CV<10% , ICC=0.85-0.86 and Pearson’s ρ=0.87) while displacement was more variable (CV=34-42%, ICC=0.34-0.50, ρ=0.59-0.72). These results are encouraging for future studies investigating aortic motion in health and aortopathy.
Reduced neonatal fronto-limbic connectivity is associated with higher externalizing symptoms in toddlers with Congenital Heart Disease
Authors: Bonthrone Alexandra , Chew Andrew , Bhroin Megan Ní , Kelly Christopher , Christiaens Daan , Pietsch Maximilian , Tournier J-Donald , Cordero-Grande Lucilio , Hajnal Joseph , Pushparajah Kuberan , Simpson John , Edwards A David , Rutherford Mary , Nosarti Chiara , Batalle Dafnis , Counsell Serena
Published: August 2023

Infants with Congenital Heart Disease (CHD) are at increased risk of neurodevelopmental impairments. Forty-three neonates with CHD underwent multi-shell high angular resolution diffusion MRI (HARDI) on a 3T scanner before surgery. At 22 months parents completed a questionnaire characterising internalizing and externalizing behaviours. Network-based statistics were used to characterise the relationship between internalizing and externalizing symptoms and structural connectivity. Reduced neonatal structural connectivity in fronto-limbic regions before surgery was associated with increased externalizing symptomatology in toddlers with CHD.
Brain Connectivity and Autistic Traits Moderated by Olfactory Perception among Children and Adolescents with Congenital Heart Defects
Authors: Schmithorst Vanessa , Wallace Julia , Polosecki Pablo , Badaly Daryaneh , Lee Vincent , Beers Sue , Meyer Pablo , Lo Cecilia , Panigrahy Ashok
Published: August 2023

We investigate the relation between congenital heart disease (CHD), autism spectrum disorder (ASD), and olfaction in a cohort of children and young adults using fcMRI (Functional Connectivity Strength; FCS, and amygdala seed-based connectivity) and DTI (RD). ASD severity was positively correlated with FCS in widespread regions, with amygdala connectivity to the DMN, and with RD in posterior parietal white matter; however, these relations were stronger in individuals with impaired olfaction scores and individuals with CHD. The relation between impaired olfaction, CHD, and ASD may be the result of individuals with impaired olfaction and/or CHD having different brain structure-function relationships.
Prenatal and Postnatal Cerebellar Development
Authors: Weisse Elizabeth , Chen Yaqing , Cataldo Alvaro Gajardo , Müller Hans-Georg , Zhu Changbo , O’Muircheartaigh Jonathan , Pietsch Maximilian , Wilson Sian , Bouchard Kristofer , Madhow Sylvia , Cole James , Biondo Francesca , D’Sa Viren , Deoni Sean C. L. , Bruchhage Muriel M.K.
Published: August 2023

The cerebellum is one of the earliest structures to develop prenatally and is documented to play an important role in motor development and, more recently, cognitive development. We investigated cerebellar development and its contribution to later overall (ELC), nonverbal (NVDQ) and verbal (VDQ) cognitive development from 22 weeks of gestation to 15 years of age. Total postnatal cerebellar volume significantly increased with ELC and VDQ but decreased with NVDQ, while prenatal cerebellar volume significantly increased with ELC with age. This could be indicative of the cerebellum’s contribution to overall cognitive development refining with development and age.
Common Genetic Variation In IGFBP7 Is Associated With Cortical Brain Development In Preterm Infants
Authors: Cromb Daniel , Cullen Harriet , De Leeuw Christiaan , Barnett Madeleine , O'Muircheartaigh Jonathan , Counsell Serena , Edwards A. David
Published: August 2023

In a cohort of 185 infants born preterm we used linked MR imaging, genomic and neurodevelopmental data, to identify a significant association between common genetic variation in the IGFBP7 gene and cortical grey matter volumes as assessed at term-corrected age (p = 0.0057), as well as motor outcomes as assessed at 18-24 months of age (p = 0.044).
Motion Correction of Contrast-enhanced Pediatric Brain MRI with Optional Non-contrast-enhanced Synthesis within a Single Neural Network
Authors: Yi Jaeuk , Kim Sewook , Lee Seul , Al-Masni Mohammed , Gho Sung-Min , Choi Young Hun , Kim Dong-Hyun
Published: August 2023

Based on the observation that motion corruption and contrast pairs do not exist in a separable way in clinically obtained pediatric contrast-enhanced scans, we developed a neural network for both motion correction and optional non-contrast-enhanced image synthesis for contrast-enhanced pediatric brain MRI. We designed a neural network architecture and training schema specific to this task. We found that motion correction performance was not degraded by doing contrast synthesis simultaneously.
Mapping Transient Co-Activity Patterns of Brain with High- and Low- Intensity Frames of fMRI Data
Authors: Li Kaiming , Hu Xiaoping
Published: August 2023

Framewise co-activity patterns of functional MRI data may reflect the transient synchronization and coordination across brain regions. High-intensity frames of resting state fMRI have revealed granulated co-activation patterns that resembled the resting state brain networks. However, whether the low-intensity frames carry such information remains unclear. The present study trained variational autoencoder models with both positive values and negative values of normalized fMRI time series respectively and evaluated the two models on a separate dataset. We found the two models were very similar, suggesting that the negative-value frames can reflect transient brain co-activity patterns as the positive ones do.
The Compressed Sensing MP2RAGE as a surrogate to the MPRAGE for neuro-imaging at 3T
Authors: Trotier Aurélien , Dilharreguy Bixente , Anandra Serge , Corbin Nadège , Lefrançois William , Ozenne Valery , Miraux Sylvain , Ribot Emeline
Published: August 2023

A Compressed Sensing Magnetization prepared Two Rapid Gradient Echo (CS-MP2RAGE) sequence was developed to provide images in <10min including reconstruction time. It was applied on 13 participants each scanned 3 to 4 times with repositioning. Compared to the standard MPRAGE sequence, it provides higher contrast morphological images. Similar intra-volunteer variabilities in volume segmentations of the brain structures were obtained. Additionally, high resolution T1 maps provided T1 values of white and gray matters and several deep grey nuclei consistent with the literature, and show very low variability (<1%). The CS-MP2RAGE can be used in future clinical research protocols.
Magnetisation transfer saturation (MTsat) and MTR: relationship with T1 recovery in multiple sclerosis and healthy brain
Authors: York Elizabeth , Meijboom Rozanna , Kampaite Agniete , Hernandez Maria Valdes , Thrippleton Michael , Waldman Adam
Published: August 2023

Magnetisation transfer saturation (MTsat) shows improved tissue contrast compared with magnetisation transfer ratio (MTR), due to T1 correction, and is more sensitive to subtle myelin loss in multiple sclerosis (MS). It is not clear how MTsat performs in severely demyelinated tissue with markedly increased T1. We examine the relationship between T1app, MTsat and MTR in healthy and MS brains. We show a negative linear relationship between MTsat and T1app in white matter, which breaks down in grey matter and white matter lesions. MTsat is sensitive to modest myelin disruption, while T1app may better reflect severe damage in MS lesions.
Quantitative Sodium MRI of the Intervertebral Discs at 7T
Authors: Scheipers Anna , Peach Daniel , Nagel Armin , Ladd Mark , Platt Tanja
Published: August 2023

23Na-MRI offers the possibility for non-invasive quantification of the sodium concentration in-vivo. The obtained functional information can provide interesting insights into the degeneration state of the human intervertebral discs1 (IVDs). The presented work thus aimed to quantify the tissue sodium concentration (TSC) in the human intervertebral discs via 23Na-MRI at 7T and to compare the obtained concentrations for two healthy volunteers after the course of one year. The estimate average concentration for all IVDs of both volunteers was found to be (96.5±8.8)mM and (113.6±9.5)mM, respectively.
2D 23Na imaging using half-VERSE pulses
Authors: Wittrich Marco , Nagel Armin , Schmitter Sebastian , Bachert Peter , Ladd Mark , Kratzer Fabian
Published: August 2023

In this work, a 2D radial 23Na sequence with half-VERSE pulses was developed to reduce SAR and achieve ultra-short TEs. Simulations and measurements of the slice profiles showed good agreement between full- and half-VERSE pulses with a maximal deviation in the FWHM of 7%.

In measurements, the TEmin was reduced from 1.41ms to 0.1ms by the use of half- instead of full-VERSE pulses. This resulted in an SNR gain of up to 18% in phantom, 7% in brain and 26% in calf measurements.

Last, rapid single-slice 23Na images (2.9x2.9x12mm3) were obtained in a clinically feasible acquisition time of 2:56min.
Assessing the repeatability of tissue sodium concentration and characterizing the bi-exponential T2* decay signal in the calf
Authors: Prestwich Ben , Francis Susan
Published: August 2023

The repeatability of sodium (23Na) MRI measures must be understood to allow for its application in clinical studies of patient groups or response to therapy. A series of 23Na scans were performed on the calf of healthy subjects, this included a 3D GRE 23Na scan and phase sensitive B1 mapping to measure tissue sodium concentration (TSC). Subjects were scanned twice for assessment of repeatability of measures. A multi echo UTE scan was used to measure the T2* decay. TSC was shown to have a coefficient of variation of 16±4 % between visits and the bi-exponential decay curve was characterized.
2D ultra-short TE imaging for 23Na MRI using half-pulse excitation
Authors: Wu Chengchuan , Johnston Leigh , Blunck Yasmin
Published: August 2023

This work implements 2D ultra-short TE (UTE) imaging for 23Na using half-pulse excitation. The sequence was examined in numerical simulations and phantom experiments at 7T. 2D UTE 23Na imaging is shown to be less prone to partial volume effects than conventional radial 3D sodium imaging and able to produce high in-plane resolution 23Na images.
Exploration of Velocity-Selective Inversion Arterial Spin Labeling for Breast Imaging
Authors: Buck Mareike , Konstandin Simon , Breutigam Nora-Josefin , Günther Matthias
Published: August 2023

In this work, the application of velocity-selective inversion ASL in healthy breast tissue is demonstrated for the first time. The measurements show a low measured signal in breast tissue. However, the prominent fat artifacts that appear in the images will need to be addressed in future work. The technique presented here has nonetheless been shown to hold promise in the field of non-invasive breast cancer diagnostics with further development, particularly the inclusion of background suppression to get clear perfusion signal.
Dual-venc Dual-echo (DVDE) Phase-contrast MRI for Simultaneous Measurement of Arterial and Venous Blood Flow
Authors: Jang Jihye , Zhao Yansong , Smink Jouke , Powell Andrew , Browne Lorna , Moghari Mehdi
Published: August 2023

Phase-contrast (PC) MRI enables non-invasive quantification of blood velocity and flow. The velocity encoding factor (venc) selected by the operator is chosen to maximize the velocity-to-noise ratio (VNR) while preventing aliasing artifacts. To minimize the acquisition time increase associated with an additional venc, a dual-venc dual-echo (DVDE) technique has been proposed where both venc images are acquired within a single TR as dual-echo images. Compared to the single-venc PC-MRI, DVDE allows simultaneous imaging of arterial and venous blood flow with an enhanced VNR and similar blood flow and velocity.
Combined T2*-diffusion imaging of the fetal lungs in normal and preterm fetuses
Authors: Avena-Zampieri Carla , Story Lisa , Cromb Daniel , Rutherford Mary , Uus Alena , Slator Paddy , Hutter Jana
Published: August 2023

Advanced functional MRI techniques were applied to the fetal lungs to increase our understanding of in-utero lung development, imperative for accurate antenatal diagnosis to identify fetuses at highest risk of morbidity. Our preliminary results show that combined T2*-diffusion imaging is a feasible technique to analyse the developing lungs in utero. A reduction in both lung volumes and T2* values associated with fetuses that subsequently delivered preterm was identified - paving the way for future more detailed in depth studies.
Dose-dependent neuroprotective effects of Bovine Lactoferrin following neonatal hypoxia-ischemia in the immature rat brain
Authors: van de Looij Yohan , Sanches Eduardo , Saw Sadou , Toulotte Audrey , Dilva Analina Da , Modernell Laura , Sizonenko Stéphane
Published: August 2023

Injuries to the developing brain due to hypoxia–ischemia (HI) are common causes of neurological disabilities in preterm babies Lactoferrin (Lf) is an iron-binding protein shown to have antioxidant, anti-inflammatory and anti-apoptotic properties when administered to mothers as a dietary supplement during pregnancy and/or lactation in preclinical studies of developmental brain injuries. Here, we tested three different doses of dietary maternal Lf supplementation using the postnatal day 3 HI model and evaluated the acute neurochemical damage profile using 1H MRS and DTI/NODDI. In conclusion, Lf supplementation attenuates, in a dose-dependent manner, the acute and long-term cerebral injury caused by HI.
Assessing Inter-Observer Variability of MRI Tagging of the Colon Contents in Healthy Human Subjects
Authors: Alshammari Meshari , Alyami Ali , Wilkinson-Smith Victoria , Marciani Luca , Moran Gordon W. , Hoad Caroline L.
Published: August 2023

MRI Tagging techniques have been applied to the GI tract to assess bowel contractions and colon content mixing. Two independent datasets of healthy adults were used to evaluate the dependence of the percentage Coefficient of variation (%CoV) measurement on inter-observer variability in the ascending colon and descending colon. There was little difference between both AC and DC measurements of the %CoV with high inter-rater agreement (intra-class correlation coefficient > 0.95). This technique could be used to provide objective measures for the motility assessment of the colon in inflammatory and functional bowel diseases.
Analyzing Radiomic Features in Magnetic Resonance Images of Head and Neck Cancer during Radiation Therapy: Preliminary Results
Authors: Fritz Victor , Schwartz Martin , Kübler Jens , Böke Simon , Habrich Jonas , Zips Daniel , Thorwarth Daniela , Nikolaou Konstantin , Schick Fritz
Published: August 2023

The aim of this work was to identify potential texture features as imaging biomarkers for monitoring treatment response in head and neck cancer (HNC). For this purpose, a total number of 93 texture features were extracted on segmented calculated ADC maps and compared at baseline and in the early treatment phase of radiation therapy (RT). Fifteen texture features showed a statistically difference in the course of RT. In particular, features suggesting that ADC-based HNC texture became finer but more heterogeneous changed significantly. Presented preliminary results offer initial findings that will be systematically investigated in upcoming studies.
Open-Source Myocardial T1 mapping accelerated with SMS: combining an auto-calibrated blip-bSSFP readout with VERSE-MB pulses
Authors: Gaspar Andreia , Silva Nuno , Nunes Rita
Published: August 2023

Clinical myocardial T1 mapping protocols typically acquire three 2D slices, each obtained in a separate breath-hold; this is only feasible in patients able to do sequential breath-holds. We propose SMS-ProMyoT1 which integrates simultaneous multi-slice (SMS) with open-source ProMyoT1, previously implemented with Pulseq, to obtain all slices in a fast single shot. SMS-ProMyoT1 differs from previous implementations by combining blip-bSSFP with VERSE-multiband for RF modulation, and auto-calibrated blip patterns for a fast self-contained sequence. The method was successfully applied both in a reference phantom and in-vivo.
Measuring the Impact of Pineapple Juice on Quantitative Liver MRI Metrics cT1, Iron and PDFF at 1.5T and 3T
Authors: Wang Yi-Chun , Sanaei-Nezhad Faezeh , Peixoto Joao , Fernandes Carolina , Smith Alex , Robson Matthew , Banerjee Rajarshi
Published: August 2023

Pineapple juice (PJ) is used in Magnetic Resonance Cholangiopancreatography to suppress gastrointestinal tract signals. To explore how PJ affects multiparametric liver MRI, 30 participants underwent scans before and after ingesting PJ. Image data were analysed with LiverMultiScan (yielding iron corrected T1 (cT1), iron, and PDFF) and statistically compared. The changes post PJ administration were statistically significant for cT1 at both 1.5T and 3T but not for iron and PDFF. However, the repeatability analysis indicates the post PJ administration cT1 changes were smaller than the repeatability limits of agreement, suggesting that PJ has neglect-able clinical effect on multiparametric liver MRI.
Improving annotation accuracy in MRI data using MR Fingerprinting and deep learning
Authors: Chen Yong , Boyacioglu Rasim , Weragoda Gamage , Martens Michael , Badve Chaitra , Griswold Mark
Published: August 2023

In this study, we introduced a new deep learning method to take advantage of both radiologists’ expertise and multi-parametric MR Fingerprinting data to improve annotation accuracy in MRI dataset. A U-Net based convolutional neural network was adopted and each dataset was evaluated multiple times using different combinations of training dataset. Our initial results obtained from a brain tumor dataset demonstrates that the developed method could effectively identify mislabeled tissues and improve annotation accuracy.
Efficient MTsat mapping using sparse MP2RAGE for T1 and M0 measurement with B1+ inhomogeneity correction
Authors: Rowley Christopher , Leppert Ilana , Campbell Jennifer , Nelson Mark , Pike G , Tardif Christine
Published: August 2023

In this study we investigate the use of MP2RAGE derived M0 and T1 maps for use in MTsat imaging. These values are compared against maps calculated from the traditional VFA approach. Additionally, the MP2RAGE approach is evaluated with and without sparse sampling and compressed sensing reconstruction. We show that VFA produces elevated T1 values, and consequently lower MTsat compared to MP2RAGE approaches. A model-based ΔB1+ correction was able to remove the dependence of MTsat on ΔB1+. The sparse MP2RAGE provided high quality maps, leading to a full MTsat protocol that was 32% faster than the traditional approach.
3D MR-STAT: towards a fast multi-parametric protocol with increased SNR
Authors: Liu Hongyan , van den Heide Oscar , Fuderer Miha , van den Berg Cornelis , Sbrizzi Alessandro
Published: August 2023

MR-STAT is a framework for simultaneous mapping of quantitative MR parameters from single short scans. In this work, we extend the current 2D Cartesian MR-STAT sequence to 3D acquisitions, in order to achieve higher SNR and isotropic resolution with a scan lasting few minutes. In particular, we implement a prototype 3D MR-STAT sequence for whole brain coverage with isotropic resolution, and test it on gel phantom and in-vivo brain data. Acceleration strategy of the 3D sequence is proposed, and the corresponding retrospective undersampling of the measured in-vivo data is reconstructed.
Simultaneous T1 and T2 mapping with QuantoRAGE: a new MP2RAGE variant using T2-prepared inversion
Authors: Bonanno Gabriele , Marques José , Kober Tobias , Hilbert Tom
Published: August 2023

T1 and T2 relaxometry provide important quantitative information and can serve as imaging biomarkers thanks to their sensitivity to pathology. However, quantitative imaging requires long scan times for high-resolution whole-brain coverage. Magnetization-prepared approaches combined with fast sequences allow for high isotropic resolution, but they are often biased due to other relaxation mechanisms than the one being probed. To account for this effect, we introduce QuantoRAGE: a new method that uses a T2-prepared inversion within an accelerated MP2RAGE sequence for simultaneous T1 and T2 mapping. Preliminary tests demonstrate the feasibility to obtain high-resolution simultaneous T1 and T2 relaxometry at 3T.
Performance of a TEM 2H/1H 7T head coil
Authors: Zhang Minghao , Karkouri Jabrane , Atkinson Daniel , Tramm Brandon , Schillak Scott , Rodgers Christopher
Published: August 2023

Deuterium metabolic imaging (DMI) has been proposed as a means to probe glucose uptake and metabolism. It is expected that DMI will reveal important changes in cancer and neurodegeneration. We constructed a dual-tuned 7T 2H/1H array coil and assessed appropriate RF power limits by EM modelling. The coil performance has been assessed with phantom scans on a D2O-enriched agar phantom. We are now ready to start human in vivo scanning.
An old tracer learns new tricks: Imaging cerebral glucose uptake with deuterated 2-deoxy-d-glucose-2,2-d2
Authors: Gao Xiao , Gordon Jeremy , Qiao Kai , Polvoy Ilona , Nickles Tanner , Wilson David , Chaumeil Myriam
Published: August 2023

2-deoxy-d-glucose (2-DG) is a glucose analog widely used in FDG-PET imaging as a biological tracer of glucose uptake. This study innovatively redirects its application in 2H NMR by using a deuterated version of 2-DG (2-DG-d2) and explores its imaging potential in mapping glucose uptake without ionizing radiation. A workflow is described here regarding multi-band RF pulse design and bSSFP sequence optimization, which enables a rapid 2H imaging with high sensitivity. Both in vitro and in vivo imaging results have validated the pulse sequence’s specificity and sensitivity of detecting 2-DG-d2 with high spatial resolution, inspiring its further implementation in the future.
A dictionary-based approach for the determination of pH values using 31P MRS
Authors: Franke Vanessa L. , Breitling Johannes , Bangert Renate , Ladd Mark E. , Bachert Peter , Korzowski Andreas
Published: August 2023

The determination of tissue pH under varying cellular conditions by means of 31P MRS is challenging. We propose a concept for a dictionary-based approach for pH estimation under different chemical conditions. As proof-of-concept, we demonstrate its feasibility for a limited subset of conditions using the chemical shifts of ATP and their dependence on pH and magnesium. For the presented subset, the estimated pH values are in good agreement with the prepared values. However, for application to in vivo data, an extension of the dictionary to include other influences, e.g. of other ions, is required and the subject of ongoing work.
Design Analysis and Prototype Construction of PNS Optimized MRI Gradient Coils
Authors: Davids Mathias , Vendramini Livia , Ferris Natalie , Klein Valerie , Guerin Bastien , Wald Lawrence
Published: August 2023

We describe the process of designing and analyzing two body gradient coils with and without PNS optimization suitable for prototype construction and experimental validation. The optimized coil achieves a 51% increase in PNS thresholds at a 15% inductance penalty. Both coils are construction-ready (single continuous wire path) and have realistic and matched design characteristics (actively shielded, torque/force balanced, high field linearity in 40 cm ROL). We are in the process of constructing coil prototypes, with the ultimate goal of experimentally validating their PNS differences.
Improving image quality and acoustic transparency in MRgFUS at 3T using a low-profile, flexible receive coil array
Authors: Saniour Isabellle , Robb Fraser , Taracila Victor , Shin James , Mishra Vishwas , Fukuda Rena , Vincent Jana , Voss Henning , Kaplitt Michael , Chazen J. Levi , Winkler Simone
Published: August 2023

Transcranial MRgFUS has been successfully used to treat a variety of neurodegenerative diseases. However, body coil brain image quality is poor, and a low-signal band artifact may occur in some regions due to RF wave reflections. Further, acoustic coil transparency has not been addressed extensively to date. In this work, we simulate a 10-channel coil design that can significantly increase the SNR by a factor of 20 over the body coil and thus indirectly improve the signal at the region of interests. Acoustic simulations/experiments exhibit transparency of the FUS-Flex coil as high as 97% at 650 kHz.
Meta-Analysis of the Normal Diffusion Tensor Imaging Values of the Median Nerve And How They Change In Carpal Tunnel Syndrome
Authors: Rojoa Djamila , Raheman Firas , Rassam Joseph , Wade Ryckie
Published: August 2023

Carpal tunnel syndrome (CTS) is the most common compressive neuropathy worldwide. Compressed peripheral nerves exhibit distorted architecture, demyelination and perineurial fibrosis. Diffusion tensor imaging (DTI) generates proxy measures of nerve ‘health’ which are sensitive to myelination, axon diameter, fibre density and organisation. This meta-analysis included 32 studies of 2643 wrists, belonging to 1575 asymptomatic adults and 1068 patients with CTS. We summarise the normal FA (0·58 [95% CI 0·56-0·59]) and MD (1·138 x10-3 mm2/s [95% CI 1·101-1·174]) of the median nerve, then show that diffusion throughout the length of the median nerve is more isotropic in patients with CTS.
Surface-Based Morphometry Analysis Shows Increased Cortical Sulcus Depth after Sound Therapy in Patients with Tinnitus
Authors: Wei Xuan , Zhu Jinxia
Published: August 2023

In this study, we performed brain surface-based morphometry to evaluate changes in sulcal depth after sound therapy in patients with idiopathic tinnitus. Our results showed that sulcal depth was significantly reduced in the left medial temporal cortex (MTC) and right somatosensory and motor cortex (SMC) of patients with tinnitus compared to the healthy controls, but increased significantly at 24 weeks after sound therapy. Therefore, sulcal depth in the auditory sensory regions of the brain is a potential neuroimaging biomarker for evaluating treatment efficacy in tinnitus patients.