bluuebunny/crossref_metadata_2025 huggingface dataset:
Identifying the role of free water in human cortical macroscopic organization
Authors: Wei Lei , Ding MIng , zhang yuwen , wang he
Published: August 2023

Free water imaging is a novel tool to study human brain. Recently, the free water has been used in aging disease researach. However, the role of free water in human cortex macroscopic is still unknown. This work shows the relationship between the cortical free water and the cortical thickness, and investigate the underlying molecular and genetic mechanism of the association. Neurons and astrocytes are strongly associated with the free water and the macroscopic organization.
Dynamic BOLD MRI Shows Greater Foot Ischemia and Blunted Reperfusion Following Cuff-Occlusion Challenge in Diabetic Patients with Foot Ulcers
Authors: Edwards Scott , Yao Jingting , Schechter Marcos , Fayfman Maya , Santamarina Gabriel , Nesbeth Paula , Giacalone Vincent , Blanco Gerado , Tirouvanziam Rabindra , Alvarez Jessica , Risk Benjamin , Rajani Ravi , Reiter David
Published: August 2023

Diabetic foot ulcer (DFU) patients often face incomplete wound healing which leads to a long-term state of inflammation and risk of infection. Prolonged wound healing is thought to result in part from impaired tissue perfusion due to microvascular disease. This study applies dynamic blood-oxygenation-level-dependent (BOLD) imaging to quantify reperfusion of tissue after induced occlusion and ischemia in the foot. When compared to a healthy population, DFU patients show an increased ischemic state during cuff occlusion and decreased reperfusion after release. Quantification of cuff-occlusion parameters may assist in the classification of DFUs and be used to predict the prognosis and enhance treatment plan.
Clinical evaluation of accelerated wideband cardiac perfusion pulse sequence in stress testing in patients with a CIED
Authors: Schwartz Sarah , Fan Lexiaozi , Allen Bradley , Collins Jeremy , Hong Kyungpyo , Carr James , Benefield Brandon , Patel Amit , Kim Daniel , Lee Daniel
Published: August 2023

This study evaluates visual scores of image quality (conspicuity, artifact, noise; Likert scale 1[worst]-5[best], 3 acceptable) produced by a wideband cardiac perfusion sequence in patients with CIED and a standard sequence in matching non-device patients in the setting of vasodilated stress perfusion imaging. The median conspicuity scores were not significantly different between wideband (4) and standard (4). While the median artifact score was significantly worse for wideband (4) than standard (5), it was above the acceptable cutoff. The median noise score was significantly better for wideband than standard. Our wideband perfusion sequence produces diagnostically acceptable image quality in CIED patients.
Exploring coupling of venous blood and CSF fluid flow using flow sensitive Real-time phase-contrast MRI (PC-MRI) during forced breathing
Authors: Sahoo Prativa , Kollmeier Jost , Kulaczewski Steffi
Published: August 2023

Venous system pathologies have increasingly been linked to disorders of CSF circulation whereas the exact coupling mechanisms still remain unknown. Using real-time phase-contrast MRI fluid dynamics of both systems were studied during normal and forced breathing in healthy subjects at spinal lumbar level L3. The aim was to provide experimental evidence that respiration couples CSF and venous flow. A correlation between CSF and venous flow could be observed during forced breathing. The findings point to a dynamic interplay between the fluid systems to regulate intracranial volume. Further insights will expand our understanding of the pathophysiology of different forms hydrocephalus.
Free-Breathing R2* Mapping for Hepatic Iron Quantification Using Respiratory Motion-Resolved 3D Multi-Echo UTE Cones MRI
Authors: Kang MungSoo , Wen Yan , Carl Michael , Behr Gerald , Otazo Ricardo , Kee Youngwook
Published: August 2023

Respiratory motion is one of the major factors hindering accurate R2* mapping for hepatic iron quantification. In this work, motion-resolved 3D multi-echo UTE cones MRI with pseudo-random view ordering was implemented for motion-robust and free-breathing R2* mapping of hepatic iron. Compared to conventional gridding reconstruction, motion-resolved reconstruction reduced the overestimation of R2* induced by respiratory motion artifacts, enabling an accurate measurement of R2*. 3D multi-echo UTE cones MRI with motion-resolved reconstruction demonstrated the feasibility of accurate free-breathing R2* mapping for hepatic iron quantification.
Prior knowledge fitting of 2H-labeled glutamate in the 1H MRS spectrum to map neural metabolism following ingestion of deuterated glucose
Authors: Wilson Neil , Cember Abigail , Rich Laurie , Bagga Puneet , Nanga Ravi , Swago Sophia , Thakuri Deepa , Elliott Mark , Schnall Mitchell , Detre John , Reddy Ravinder
Published: August 2023

Deuterium metabolic imaging (DMI) has brought about a renewed interest in the application of 2H-labeled substrates to map metabolism in vivo, yet deuterium spectroscopy remains challenging. We have shown that metabolism of deuterium-labeled glucose can be observed in the proton spectrum through a reduction in signal of downstream metabolites in a technique called quantitative exchange label turnover MRS (qMRS). Here, we show that prior knowledge fitting that includes unlabeled as well as deuterium-labeled forms of glutamate can be used to map neural metabolism reliably with qMRS.
Monitoring water uptake in the human body during oral loading of heavy water using deuterium magnetic resonance
Authors: Cocking Daniel , Damion Robin , Franks Hester , Wilkinson Daniel , Auer Dorothee , Brook Matthew , Bowtell Richard
Published: August 2023

Deuterium magnetic resonance imaging and spectroscopy at 7T has been used to follow the deuterium concentration in the brain over an ~eight-hour period while subjects orally-loaded with D2O to 100x natural abundance. Changes in deuterium concentration of ~ 0.1% can be readily monitored in 2H spectra acquired in 1 minute and images acquired in 7.5 minutes. The change in deuterium concentration estimated from 2H spectra is in agreement with the value calculated from cumulative D2O dose and body mass and the signal changes measured from ROIs in the brain have similar time-courses, with relative signal strengths dictated by T2*-weighting.
Functional 31P MRS in the visual cortex at 9.4 T
Authors: Pohmann Rolf , Scheffler Klaus
Published: August 2023

Even after a large number of studies with varying outcome, the effect of brain activation on the 31P spectrum is still unclear. Here, the SNR gain expected from a field strength of 9.4 T is used to determine changes in the metabolite peaks during a 5 min stimulus. In spite of the high SNR and spectral quality, no significant variations were found. Especially the amplitude and linewidth of the PCr-peak did not change, and, while the signal of extracellular inorganic phosphate was well visible after averaging over all subjects, no variations in its amplitude or position were observed.
Microstructural alteration of trigeminal nerve revealed by DTI and its correlation with vascular compression and pain
Authors: Guo Tiantian , Bu Chunqing , Shi Chuanying , Su Daoqing , Wu Peng , Zhang Chuanchen
Published: August 2023

Classical Trigeminal Neuralgia (CTN) is mainly caused by vascular compression of the trigeminal nerve. We analyzed the correlation between the fractional anisotropy (FA) / apparent diffusion coefficient (ADC) values of the bilateral trigeminal nerves and the degree of neurovascular compression (NVC) for CTN patients. Results shown the FA value is negatively correlated with the degree of NVC on the symptomatic side. FA values was lower if there was NVC on the asymptomatic side compared with no NVC. The correlation between FA and visual analogue scale (VAS) scores indicates that FA was a potential MR indicator for predicting patient clinical symptoms.
Quantitative UTE Double Echo Steady State (qUTE-DESS) for Simultaneous Mapping of T1, T2, and Diffusivity of Short T2 Tissues – Ex Vivo Study
Authors: Jang Hyungseok , Ma Yajun , Masoud-Afsahi Amir , Jerban Saeed , Lombardi Alecio , Chang Eric , Chung Christine , Du Jiang
Published: August 2023

Quantitative double echo steady state (DESS) imaging allows simultaneous estimation of T1, T2, and apparent diffusion coefficient (ADC) maps with high spatial resolution. Recently, ultrashort echo time (UTE) based DESS has been investigated targeting short T2 tissues. However, ADC mapping for tissues with short T2 values using DESS is challenging due to the two competing factors: sensitivity to diffusion that requires a long TR and sensitivity to short T2 component that requires a short TR. In this study, the feasibility of using quantitative UTE DESS (qUTE-DESS) to image connective tissues in the knee was investigated.
Correlating neurite density and synaptic density in the human brain in vivo with diffusion-weighted PET-MR
Authors: Christiaens Daan , Casteele Thomas Vande , Laroy Maarten , Van Cauwenberge Margot , Van den Stock Jan , Boeckaert Filip , Sunaert Stefan , Vandenbulcke Mathieu , Maes Frederik , Emsell Louise
Published: August 2023

11C-UCB-J PET offers a unique imaging modality to map synaptic density in the human brain in vivo with high specificity. Here, we investigate its correlation with several diffusion MRI metrics and microstructure model parameters in diffusion-weighted PET-MR. We report moderate negative correlation of 11C-UCB-J uptake with measures of anisotropy, consistent with a hypothesis that higher synaptic density is associated with a more disorganised neurite configuration. We also find weak positive correlation to the intra-axonal signal fraction in cortical grey matter. As such, 11C-UCB-J PET-MR can further the interpretation and in vivo validation of more advanced microstructure models of grey matter.
Susceptibility corrected Proton Resonance Frequency Shift based MR Thermometry of hepatic Microwave Ablation in an in-vivo swine model
Authors: Gutberlet Marcel , Pannicke Enrico , Bruesch Inga , Rumpel Regina , Wittauer Eva-Maria , Vondran Florian W. R. , Wacker Frank , Hensen Bennet
Published: August 2023

In microwave ablation (MWA), heat induced susceptibility changes impair the assessment of the ablation zones using proton resonance frequency shift based magnetic resonance (MR) thermometry. In this work, these heat related field changes were modelled to improve the accuracy of MR thermometry to monitor microwave ablation. In a study of hepatic MWA in an in-vivo swine model, the proposed method provided increased accuracy to assess the ablation zone compared to uncorrected MR thermometry.
Dynamic Contrast Enhanced MR perfusion of the Spinal Cord with radial streaking artefacts reduction at 3T: Preliminary results and applications
Authors: Frébourg Guillaume , Farah Kaissar , Troalen Thomas , Pini Lauriane , Destruel Aurélien , Fuentes Stéphane , Guye Maxime , Callot Virginie
Published: August 2023

3T T1-GRASP acquisition combined with an optimized dynamic radial streaking artefacts reduction have been set up to analyze Dynamic Contrast Enhanced MRI (DCE) over time and spinal cord levels. Acquisition with Gd-injection using the best temporal resolution parameters have been applied on two healthy volunteers and one patient showing perfusion dysfunction with compression. Semi-quantitative parameters (SQP) have been calculated in different regions of interest along the cervical levels and voxel-wise to provide SQP axial mapping of the spinal cord.
MRI Estimates of Cerebral Blood Flow and Venous Oxygenation as Surrogate Markers in a Mouse Model for Sickle Cell Anemia
Authors: Yen Yi-Fen , Mandeville Joseph , Chan Yin-Ching , Chan Suk-Tak , Hardy Erin , Janz Jay , Arkin Steven , Rybin Denis , Knee Kelly , Pittman Debra , Goodman James
Published: August 2023

We have assessed cerebral blood flow (CBF), venous T2, and hematocrit (Hct) in mice to characterize the performance of MR markers of cerebral physiology in wildtype (WT) mice and the Townes transgenic mouse model of Sickle Cell Disease (SCD). SCD mice exhibited increased CBF, decreased venous T2, and decreased Hct compared to matched WT mice. Combining MR measures of CBF and venous T2 with Hct measurement improved the disease-specific differentiation. Test-retest variability was approximately 20% for CBF and venous T2 and 10% for Hct. Methods employed in this study are fully translational to the clinic.
Multi-modal Study Comparisons of Hemodynamics after a Traumatic Brain Injury (TBI) and Subarachnoid Hemorrhage (SAH)
Authors: Dieckhaus Laurel , Kamali Ali , Peters Emily , Preszler Collin , Sonderer Christa , Pires Paulo , Laksari Kaveh , Hutchinson Elizabeth
Published: August 2023

To examine the first hours after brain injury, we utilized photoacoustic imaging (PAI), ultrasound (US), and color doppler (CD) alongside MRI metrics. We wanted to investigate the early pathomechanisms that involve hemodynamic response such as blood flow, oxygenation, and edema.
Dynamic Changes in Lung Water Density and Volume with Changes in Body Position
Authors: Goodhart David , Grenier Justin , Stobbe Rob , Seres Peter , Thompson Richard
Published: August 2023

We aim to describe the dynamic response of the distribution of lung water to the change in position from standing to supine. An efficient UTE MRI trajectory (Yarnball) provided 3D images (free-breathing, 74 seconds acquisition) in 3 volunteers, with 10 repeated scans over ~14 minutes. Lung water density (LWD) increased over time but total lung water content remained constant, consistent with a measured decrease in lung volume over time. LWD increased by a larger extent towards the back, suggesting a larger lung volume reduction in gravity dependent regions (the back) over time. Steady-state LWD was not achieved in 14 minutes.
Estimation of numerical substrate properties with compartmentalized models from Monte-Carlo simulated DW-MRI signals
Authors: Gardier Rémy , Haro Juan Luis Villarreal , Canales-Rodriguez Erick , Girard Gabriel , Rafael-Patiño Jonathan , Thiran Jean-Philippe
Published: August 2023

For over a decade, microstructure imaging has been a hot research topic in DW-MRI. Tissue complexity compelled researchers to make assumptions about certain properties. The inverse problem of microstructure imaging, in particular, is ill-posed, and current methods fix some parameters to reduce the solution space. In this abstract, we look at how intracellular and extracellular diffusion coefficients affect the estimation of compartmentalized model parameters. We show that robust estimation of some parameters does not extend to all parameters using Monte-Carlo simulations in impermeable substrates with multiple diffusivities, and we identified the extracellular compartment as the most influential on estimation quality.
Temporally improved volume registration by data driven subvolume interpolation of simultaneous multislice EPI time series
Authors: Dabrowski Oscar , Dabrowski Oscar , Courvoisier Sébastien , Falcone Jean-Luc , Klauser Antoine , Songeon Julien , Kocher Michel , Chopard Bastien , Lazeyras Francois
Published: August 2023

In the context of EPI time series acquisition, fast motion occurring below the Nyquist limit (< 1 TR), present a problem for accurate registration by 3D rigid-body algorithms. A method for temporally upsampling SMS EPI acquisitions is proposed. EPI volumes are splitted into subvolumes according to the temporal acquisition order of SMS and interpolated using a data driven approach based on pairwise affine transforms and linear interpolation. A proof of concept based EPI acquisitions of controlled head choreographies shows that fast motion below the Nyquist rate can be more accurately estimated by our method.
Findings during tuning procedure of a 7T radiofrequency transmit resonator
Authors: Martins Tiago , Ibrahim Tamer
Published: August 2023

In this work, we explain the tuning procedure for a new conforming Tic-Tac-Toe (TTT) array and the findings that were observed during this procedure. These findings help shape how the array can be used in building a 7 Tesla RF coil system for neuroimaging applications.. It is shown that a 2-channel and 4-channel configurations can be tuned similarly and produce similar magnetic field distribution and intensities.
The association between white matter hyperintensity shape and long-term dementia outcome in community-dwelling older adults
Authors: Keller Jasmin , Sigurdsson Sigurður , Klaassen Kelly , Scholte Eveline , Hirschler Lydiane , van Buchem Mark , Launer Lenore , van Osch Matthias , Gudnason Vilmundor , de Bresser Jeroen
Published: August 2023

Recently white matter hyperintensity (WMH) shape was introduced as a promising novel marker that may provide a more detailed characterization of WMH than volume alone. We aimed to investigate the association between WMH shape and the occurrence of dementia later in life in community dwelling older adults. WMH shape markers and WMH volumes were determined for periventricular/confluent, and deep WMH. A more complex shape of periventricular/confluent WMH (higher fractal dimension), as well as total and periventricular/confluent WMH volume, were associated with a greater risk of dementia. These results may indicate a prognostic value of WMH shape markers.
Inter-reader variability in apparent diffusion coefficient measurements for assessment of breast cancer response to neoadjuvant therapy
Authors: Le Nu , Li Wen , Onishi Natsuko , Newitt David , Gibbs Jessica , Wilmes Lisa , Kornak John , Partridge Savannah , Price Elissa , Joe Bonnie , Esserman Laura , Hylton Nola
Published: August 2023

This study presents a retrospective analysis of inter-reader variability in tumor ADC measurements extracted from three types of ROIs using data from the multi-center I-SPY 2 trial. Overall, good agreement was observed between two readers. Mean ADCs measured in restricted ROIs were highly reproducible by manual delineation. Mean ADCs of multi-slice restricted ROIs showed higher ICCs than single-slice restricted ROIs.
MRI with Sub-Millisecond Temporal Resolution: SPIRE Imaging of a High-speed Motion Phantom
Authors: Johannes Fischer , Bock Michael
Published: August 2023

Imaging sequences with sub-millisecond temporal resolution based on single point imaging (SPI) are very time inefficient. We designed and imaged a motion phantom capable of velocities up to 5.5m/s. A synchronization signal is acquired using a photoelectric barrier and combined with a sequence trigger signal. Reconstructed images show clear delineation of small structures with a spatial resolution of $$$\Delta x$$$=0.67mm and a temporal resolution of $$$\delta t$$$=246μs.
Fast and motion robust 2D T2 TSE Propeller acquisition of the prostate with Compressed SENSE: comparison with conventional SENSE acquisition
Authors: Bischoff Leon , Katemann Christoph , Weber Oliver , Isaak Alexander , Kravchenko Dmitrij , Mesropyan Narine , Endler Christoph , Vollbrecht Thomas , Pieper Claus , Attenberger Ulrike , Luetkens Julian
Published: August 2023

Multiparametric MRI (mpMRI) of the prostate can detect clinically significant prostate cancer in men. To accelerate the time-consuming acquisition process, we integrated a new Compressed SENSE (CS) method for T2-weighted sequences with propeller acquisition and compared it qualitatively and quantitatively to conventional SENSE accelerated T2-weighted propeller sequences. We could demonstrate that while the new CS acquisition method has less artifacts, better image sharpness and higher apparent signal-to-noise ratio (aSNR) and contrast-to-noise ratio (CNR), it reduced the acquisition time by 24%. These findings indicate a superiority over the conventional T2-sequence and could improve the diagnostic workup of patients with prostate cancer.
Segmented accelerated multi-shot diffusion imaging combined with reverse polarity gradient (RPG) correction
Authors: Johansson Jens , Lagerstrand Kerstin , Svensson Pär-Arne , Madore Bruno , Hebelka Hanna , Maier Stephan
Published: August 2023

The inherent low bandwidth along the phase encoding direction in diffusion-weighted imaging with echo-planar signal readout can cause severe image distortions. These artifacts arise near tissue boundaries and are caused by static magnetic field inhomogeneities. Correction of such artifacts can considerably improve clinical value. We combine a previously presented segmented accelerated multi-shot diffusion imaging method with reverse polarity gradient (RPG) for markedly improved reduction of geometric distortions.
Amortised inference in diffusion MRI biophysical models using artificial neural networks and simulation-based frameworks
Authors: Patron Jose Pedro Manzano , Kypraios Theodore , Sotiropoulos Stamatios
Published: August 2023

Inference in imaging-based biophysical modelling provides a principled way of estimating model parameters, but also assessing confidence/uncertainty on results, quantifying noise effects and aiding experimental design. Traditional approaches in neuroimaging can either be very computationally expensive (e.g., Bayesian) or suitable to only certain assumptions (e.g., bootstrapping). We present a simulation-based inference approach to estimate diffusion MRI model parameters and their uncertainty. This novel framework trains a neural network to learn a Bayesian model inversion, allowing inference given unseen data. Results show a high level of agreement with conventional Markov-Chain-Monte-Carlo estimates, while offering 2-3 orders of magnitude speed-ups and inference amortisation.
Optimization of an RF array for cardiac magnetic resonance at 8.5 MHz
Authors: Davies Gareth , Stormont Robert , Broche Lionel , Dawson Dana , Lurie David , Ross P
Published: August 2023

The SNR and inter coil coupling properties of a range of litz wire coils, in conjunction with the circuitry to match the coils to a low impedance pre-amplifier, were examined. The results of these studies were combined with observations of SNR and coil coupling found in the images of phantoms, obtained with various array designs, to construct an RF array optimized for 0.2 T (8.5 MHz). The array has demonstrated its capability in acquiring cardiac images from human volunteers in our field cycling imager.
Respiration volume per time (RVT) as a surrogate for end-tidal CO2 to map hemodynamic lag with BOLD fMRI
Authors: Zvolanek Kristina , Moia Stefano , Stickland Rachael , Caballero-Gaudes César , Bright Molly
Published: August 2023

Using a breath-hold task to modulate end-tidal CO2 during a BOLD fMRI scan is an established method to map hemodynamic lag. However, end-tidal CO2 measurements may not be reliable in less compliant subjects and require additional monitoring equipment. We investigated whether a related metric, respiration volume per time (RVT) can be used as a surrogate for end-tidal CO2 by directly comparing the lag values derived from each physiological measurement. Similar spatial variation was observed in healthy adult participants, albeit with some degree of proportional bias, indicating respiration belt data can be used as an alternative to map hemodynamic lag.
Volume of hyperintense inflammation (VHI): a deep learning-enabled quantitative imaging biomarker of inflammation load
Authors: Bray Timothy , Hepburn Carolyna , Jones Alexis , Bainbridge Alan , Zhang Hui , Hall-Craggs Margaret
Published: August 2023

Short inversion time inversion recovery (STIR) MRI is widely used in clinical practice to identify and quantify inflammation in patients with axial spondyloarthritis. However, assessment of STIR images is limited by the qualitative nature of image interpretation, which depends on observer expertise, and can be biased by the clinical setting. To address this, we propose the volume of hyperintense inflammation (VHI) as a quantitative imaging biomarker of inflammation load, underpinned by a recently-described segmentation method incorporating deep learning and intensity-based segmentation.
Fast Multi-Parametric Mapping with an Extended Spiral and Off-Resonance Readout Correction
Authors: van Valenberg Willem , Kotek Gyula , Vogel Mika , Hernandez-Tamames Juan , Poot Dirk
Published: August 2023

Single-shot quantitative methods with spiral sampling can increase the readout duration to reduce undersampling artifacts in the images and their propagation to the parameter maps. However, a longer readout increases blurring due to the off-resonance field if not accounted for in the reconstruction. We propose an efficient reconstruction that 1. corrects for blurring due to the off-resonance field, and 2. reduces undersampling artifacts by constraining the signal variation in each voxel to a predetermined subspace. The reconstruction method is shown to enable accurate multi-parametric mapping of a single-shot MP-b-nSSFP acquisition with submillimeter resolution in 1.8s.
Evaluating the impact of respiratory binning strategies on 4D-MRI reconstruction for an MR-Linac
Authors: Lecoeur Bastien , Barbone Marco , Alexander Sophie , Gough Jessica , Oelfke Uwe , Luk Wayne , Wetscherek Andreas
Published: August 2023

In the context of MR-guided radiotherapy, 4D-MRI is of particular interest for lung and abdominal cancer treatment, as it enables quantifying the extent of respiratory motion at the time of treatment, facilitating time-efficient midposition treatments. To reduce long reconstruction times of iterative compressed sensing-based reconstructions involving algorithms, such as XD-GRASP, we used a fast C++ implementation. We evaluated the impact of using overlapping respiratory bins and different self-gating signals on image quality and reconstruction time in multiple patients with and without abdominal compression belts.
Intraocular pressure elevation induces vascular and functional brain changes: A relative cerebrovascular reactivity resting-state fMRI Study
Authors: Chan Russell , Xue Yixi , Bang Ji Won , Faiq Muneeb , Sajitha Thajunnisa , Lee Royce , Liu Peiying , Leung Christopher , Wollstein Gadi , Schuman Joel , Chan Kevin
Published: August 2023

Recently, we used a novel resting-state fMRI method to map relative cerebrovascular reactivity (rCVR) without gas challenge, and demonstrated decreased rCVR in the visual cortex and increased rCVR in the basal forebrain in glaucoma patients relative to healthy subjects. However, the underlying mechanisms remain unclear. Here, we applied a hydrogel-induced glaucoma mouse model to chronically elevate intraocular pressure, mapped rCVR using resting-state fMRI, and measured optomotor responses. Our results showed similar patterns of rCVR changes along with visual impairments, indicating a role of chronic intraocular pressure elevation on the widespread vascular and functional brain changes in experimental glaucoma.
Ultra-Short Echo Time 31P 3D MRSI at 3T with Novel Rosette k-space Trajectory
Authors: Bozymski Brian , Shen Xin , Özen Ali , Ilbey Serhat , Thomas Albert , Chiew Mark , Dydak Ulrike , Emir Uzay
Published: August 2023

Feasibility of a novel, rosette trajectory UTE (70 μs) 3D 31P MRSI sequence is tested at 3T in phantoms and in upper leg scan with healthy subject. Braino phantom, proton resolution phantom, and highly concentrated 31P phantom test demonstrated proper reconstruction and metabolite localization. In vivo calculations of acquired PCr and β-ATP signals showed competitive SNR across 20 voxels of interest. With further acceleration, the sequence may serve as a superior alternative to conventional weighted 3D MRSI, allowing for greater SNR or resolution in briefer times. Notably, this unprecedentedly short UTE 31P MRSI intrinsically avoids baseline and phasing issues.
Developing pattern recognition models to extract longitudinal network-based measures at an individual level
Authors: Colato Elisa , Wheeler-Kingshott Claudia , Arnold Douglas , Barkhof Frederik , Ciccarelli Olga , Chard Declan , Eshaghi Arman
Published: August 2023

Network-based measures can outperform regional and whole-brain grey matter (GM) measures in explaining clinical disability in several neurodegenerative disorders. However, network measures are mostly estimated at the group level and require a re-estimation of model parameters when applied to new participants. Here, we introduce a new longitudinal network analysis paradigm to extract longitudinal ICA-like components at an individual level from a discovery cohort, applied machine learning to obtain individual-level network-based measure for a validation cohort, and used them to explain clinical disability in multiple sclerosis.
Evaluating physiological gradients after bias field correction of Hyperpolarized 129Xe Gas Ventilation MRI
Authors: Lu Junlan , Leewiwatwong Suphachart , Mummy David , Driehuys Bastiaan
Published: August 2023

Quantitative analysis of hyperpolarized 129Xe ventilation imaging requires overcoming the ill-posed problem of accurately correcting for bias field. The standard solution of N4ITK bias field correction removes not only bias field, but also physiologic gradients of interest. An alternative approach is applying RF depolarization mapping in a cohort of subjects to construct a bias field template. Here, we compare the effect that these different bias field correction techniques have on the 129Xe MRI ventilation gradients in a cohort of healthy patients (n=18).
Combining machine learning and mathematical modeling in estimation of T1 relaxation time
Authors: Škardová Kateřina , Galabov Radek , Fricková Kateřina , Pevný Tomáš , Tintěra Jaroslav , Oberhuber Tomáš , Chabiniok Radomír
Published: August 2023

A method for estimating tissue parameters using cardiovascular MRI and biophysical model by combining neural network (NN) and numerical optimization (NO) is illustrated on estimating $$$T_1$$$ relaxation time from MOLLI. Compared to the estimation obtained from MOLLI by the scanner, the proposed method provided $$$T_1$$$ closer to turbo spin-echo pseudo-ground in 7 out of 8 phantoms and higher or comparable myocardial and blood $$$T_1$$$ in 6 out of 7 patiens’ datasets. Including the NN-based initial guess accelerated the subsequent NO. NO initialized by NN, trained using simulated data, showed the potential to increase the efficiency and robustness of parameter estimation.
White matter microstructure characterisation in hippocampal sclerosis and cryptogenic temporal lobe epilepsy
Authors: Rolandi Nicolò , Palesi Fulvia , Padelli Francesco , Giachetti Isabella , Aquino Domenico , Summers Paul , Tartara Elena , Germani Giancarlo , Mariani Valeria , D'Angelo Egidio , Tassi Laura , Wheeler-Kingshott Claudia Gandini , Vitali Paolo
Published: August 2023

Temporal lobe epilepsy is characterised by heterogeneous aetiology. In this work we focused on hippocampal sclerosis and cryptogenic groups. In order to characterize microstructure white matter alterations underlying the pathology, we performed a regional analysis of the temporal lobe white matter. Our results showed less disruptive microstructural changes in cryptogenic patients. Alterations in Axial Diffusivity and Neurite Density Index in hippocampal sclerosis potentially indicate significant axonal degeneration. Further investigations are needed to ascertain the value of Orientation Dispersion Index as a possible biomarker to predict surgery outcome.
Application of Machine Learning in Comparison between Multimodal Neuroimaging Markers of Laterality in Temporal Lobe Epilepsy
Authors: Fallahi Alireza , Pooyan Mohammad , Mehvari-Habibabadi Jafar , Tabatabaei Narges Hoseini , Ay Mohammadreza , Nazem-Zadeh Mohammad-Reza
Published: August 2023

Five neuroimaging markers including T1 volume, FLAIR signal intensity, and mean diffusivity in hippocampus, and fractional anisotropy in both posteroinferior cingulum and crus of fornix were used for lateralization of temporal lobe epilepsy (TLE). Support vector machine (SVM) was used as a classifier and for measuring the importance of neuroimaging attributes. The classification results demonstrated that the hippocampal volumetric and mean diffusivity showed the highest correct classification rate and the largest area under the curve (AUC) for the receiver operating characteristic (ROC), thus considered as the most important attributes of TLE laterality among all markers investigated in this study.
Think outside the box: Exploiting the imaging workflow for Deep Learning based motion estimation and correction
Authors: Hossbach Julian , Splitthoff Daniel , Clifford Bryan , Polak Daniel , Lo Wei-Ching , Cauley Stephan , Maier Andreas
Published: August 2023

Estimating intrascan subject motion enables the reduction of motion artifacts but often requires further calibration data e.g. from an additional motion-free reference. In this work, we explore how the reuse of supplementary scans in the imaging workflow can be used as motion calibration data. More specifically, the preceding parallel imaging calibration scan is reutilized to support a Deep Learning (DL) approach for estimating motion. Results are presented which indicate that DL, in contrast to a conventional optimization approach, can extract the motion and improve the image quality despite contrast differences between the calibration and imaging scans.
Longitudinal Multiple Sclerosis Lesion Segmentation Using Pre-activation U-Net
Authors: Ashtari Pooya , Barile Berardino , Sappey-Marinier Dominique , Van Huffel Sabine
Published: August 2023

Automated segmentation of new multiple sclerosis (MS) lesions in MRI data is crucial for monitoring and quantifying MS progression. Manual delineation of such lesions is laborious and time-consuming since experts need to deal with 3D images and numerous small lesions. We propose a 3D encoder-decoder architecture with pre-activation blocks to segment new MS lesions in longitudinal FLAIR images. We also applied intensive data augmentation and deep supervision to mitigate the limited data and the class imbalance problem. The proposed model, called Pre-U-Net, achieved a Dice score of 0.62 and a sensitivity of 0.58 on the public challenge MSSEG-2 dataset.
Residual U-net for denoising 3D low field MRI
Authors: Senft Tobias , Ayde Reina , Fiorito Marco , Salameh Najat , Sarracanie Mathieu
Published: August 2023

Low magnetic field (LF) MRI is currently gaining momentum as a complementary, more flexible and cost-effective approach to MRI diagnosis. However, the impaired signal-to-noise ratio challenges its relevance for clinical applications. Recently, denoising of low SNR images using deep learning techniques has shown promising results for MRI applications. In this study, we assess the denoising performance of residual U-net architecture on different SNR levels of LF MRI data (0.1 T). The model performance has been evaluated on both simulated and acquired LF MRI datasets.
Numerical optimization and validation of Lactate CEST (LATEST) imaging at 3T: In-situ and in-vivo feasibility studies
Authors: Radke Karl Ludger , Abrar Daniel , Frenken Miriam , Wilms Lena , Boschheidgen Matthias , Liebig Patrick , Ljimani Alexandra , Nebelung Sven , Wittsack Hans-Jörg , Müller-Lutz Anja
Published: August 2023

Quantification of altered lactate concentrations with non-invasive MR imaging is of diagnostic interest in a broad spectrum of diseases and further analysis of athletic activity. In this context, chemical exchange saturation transfer (CEST) is an increasingly validated contrast mechanism in MRI. However, successful application of CEST requires efficient selective saturation of the exchanging lactate protons. In this study, we successfully optimized and investigated the application of intramuscular lactate CEST imaging (LATEST) supported by numerical simulations and were able to apply LATEST for the first time in-vivo at 3.0 T.
A Wireless Pilot Tone Based Patient Squeeze-Ball (P2TSB)
Authors: Bacher Mario , Speier Peter , Bollenbeck Jan
Published: August 2023

We developed a prototype wireless patient alarm-ball based on Pilot Tone technology which could speed up patient setup time and increase patient comfort. The use of Pilot Tone as a means of signal transmission enables easy and cost-effective use of this concept on existing scanners with only a minimal software upgrade.
Independent component analysis of rsfMRI data in pedophilic disorder: A Swedish case control study
Authors: Andersson Linnéa , Rahm Christoffer , Liberg Benny , Ljungberg Maria , Björkman-Burtscher Isabella
Published: August 2023

Fifty percent of all child sexual abuse (CSA) perpetrators are individuals with pedophilic disorder. The neural underpinnings of pedophilic disorder are unknown. We conducted a case-control study aiming to investigate functional connectivity alterations using independent component analysis on resting state fMRI data in search of biomarkers that can be used for preventing CSA. The results suggest there are functional connectivity alterations in several resting state networks in individuals with pedophilic disorder.
1H-MRS of bile in the gallbladder in subjects without and with hepatic steatosis
Authors: Machann Jürgen , Stefan Norbert , Birkenfeld Andreas , Schick Fritz
Published: August 2023

1H-MRS of bile was performed in 54 healthy subjects at increased risk for metabolic diseases. Additionally, intrahepatic lipids (IHL) were quantified. Concentration of main peaks of bile was calculated in relation to non-suppressed water signal. Large interindividual differences in concentration of the bile-peaks with significantly lower concentrations in subjects with increased IHL were detected. Males show a tendency towards higher concentrations in all bile-peaks as well as in IHL (n.s.). It remains speculative, whether or not these MRS-derived results might play a role in the pathogenesis of insulin resistance – further analyses with assignable metabolic and laboratory data are recommended.
A deep learning image based calibration model to predict motion using auxiliary sensors
Authors: Tibrewala Radhika , Keerthivasan Mahesh , Block Kai Tobias , Paska Jan , Brown Ryan
Published: August 2023

For MRI hindered by motion artifacts sensors are able to provide a surrogate for bulk motion, but may not be tissue specific. In this work, we use deep learning to build a motion model with an auxiliary pilot tone sensor during a fast-image calibration step. A neural network is used to learn the correlation between the pilot tone signal and the pixel-wise liver displacement which is predicted using an automatic segmentation model. The motion model is used to predict displacement on low frame rate images, thus offering the opportunity to perform motion resolved reconstruction.
Prospective Motion Correction for a Full Neuroimaging Protocol in Elderly Subjects at 7T
Authors: Carlson Mackenzie , DiGiacomo Phillip , Burns Brian , Spincemaille Pascal , Wang Yi , Maclaren Julian , Aksoy Murat , Rutt Brian , Zeineh Michael
Published: August 2023

Correction of head motion during MRI scanning is critical to achieving high-resolution images to study and quantify small regions such as the hippocampus in Alzheimer’s disease. Our optical prospective motion correction prototype system has previously demonstrated improved image quality in volunteers at 7T, but clinical translatability has been lacking. In this work, we implemented an integrated power supply and applied prospective correction to a broad set of sequences, including mGRE and FSE, for a clinically relevant research protocol with emphasis on hippocampal iron imaging. Metrics achievable using our protocol include high-resolution cortical QSM, hippocampal subfield QSM and volume.
MoCoPad: A new soft sensor system for fast head motion detection and tracking in MRI
Authors: Sengupta Saikat , Musa Mishek , Chen Yue
Published: August 2023

In this abstract we present initial feasibility results of a novel pneumatic sensor-based head motion detection and tracking system for MRI. The system comprises of head pad with a built in matrix of air pressure sensors, which replaces the standard head pad in an MRI scan and allows fast sequence agnostic tracking of head motions without the need for navigators, head markers or camera systems. Here, we show initial results for motion detection and head pose estimation in phantom studies using a motion model trained outside the scanner.
Evaluating the match of image quality metrics with radiological assessment in a dataset with and without motion artifacts
Authors: Eichhorn Hannah , Chemnitz-Thomsen Simon , Vouros Evangelos , Shekhrajka Nitesh , Frost Robert , van der Kouwe André , Ganz Melanie
Published: August 2023

Currently no image quality metric, used for evaluating the performance of artifact correction or image reconstruction methods, is sensitive to all possible image artifacts. This complicates the choice of a proper quantitative quality measure. To provide assistance with this choice, we investigated the correlation of commonly used metrics with radiological evaluation on a dataset acquired with and without motion. The full-reference metrics SSIM and PSNR correlated most strongly with observer scores. Among the reference-free metrics Image Entropy, Average Edge Strength and Tenengrad measure showed a consistent correlation for all investigated sequences.
Time-Generalized Biot-Savart Law for $$$B_1$$$, $$$B_1^+$$$, and $$$B_1^-$$$ Field Computations up to 7T MRI
Authors: Mahmutovic Mirsad , Hansen Sam-Luca , Keil Boris
Published: August 2023

Numerous methods for field computations of RF coils have been developed in the past. All these methods are based on Maxwell's equations or their derived wave equation. However, these methods are difficult to implement and not very intuitively to handle. In this work, we have investigated the suitability of the time-generalized Biot-Savart-law for $$$B_1$$$, $$$B_1^+$$$ and $$$B_1^-$$$-field computations. We showed that this method can be easily implemented and that the obtained results are a good approximation when reflections are neglectable.
Reducing Between-Subject Variability in Stimulus-Evoked BOLD fMRI Using Breath Hold-Derived Vascular Covariates
Authors: Biondetti Emma , Chiarelli Antonio , Lipp Ilona , Stickland Rachael , Villani Alessandro , Patitucci Eleonora , Tomassini Valentina , Wise Richard
Published: August 2023

The representation of changes in neural activity by blood oxygenation level-dependent (BOLD) fMRI is affected by vascular properties including cerebral blood volume (CBV) and cerebral vascular reactivity (CVR). Here, we investigate these factors using a breath-hold BOLD fMRI experiment. We show that a group-level correction of the stimulus-evoked BOLD fMRI signal by these vascular properties reduces between-subject variability and improves sensitivity to the task response. Notably, correcting with a marker of relative CBV does not require individual recordings of exhaled carbon dioxide (in contrast with CVR) and resulted in the highest increase in sensitivity to the task.
MAGNETIC RESONANCE ACOUSTIC RADIATION FORCE IMAGING (MR-ARFI) FOR THE MONITORING OF MR-GUIDED HIFU THERAPY
Authors: Choquet Karine , Vappou Jonathan , Ishak Ounay , Gangi Afshin , Breton Elodie
Published: August 2023

Tissue biomechanical properties are highly promising biomarkers for HIFU ablation monitoring. A quantitative, MR-acoustic radiation force imaging (ARFI)-based method is proposed for measuring both tissue elasticity and viscosity, together with PRFS-derived temperature. This method is based on the identification of the MR-ARFI focal spot pattern. The method was first validated in a phantom with known properties. The method was then evaluated during HIFU heating in a gelatin phantom. Both elastic modulus and viscosity were found to decrease as temperature increased. These results highlight the ability of this method to provide new, quantitative biomarkers of tissue thermal damage in real time.
Deep learning-assisted ablative margin analysis for MR-guided prostate focal cryoablation: feasibility and initial retrospective validation
Authors: Schouten Daan , Slump Cees , Fütterer Jurgen , Bomers Joyce , Overduin Christiaan
Published: August 2023

MR-guided focal cryoablation is an emerging treatment option for localized prostate cancer, however local recurrence due to incomplete ablation is not uncommon. Ablation completeness is typically assessed on intraprocedural imaging by side-by-side comparison, but a volumetric approach is lacking. We present a deep learning-assisted algorithm for near real-time ablative margin monitoring during cryoablation procedures. Retrospective validation in 27 patients after MR-guided prostate cryoablation demonstrated significantly smaller minimal ablative margin and percentual tumour coverage for patients with versus without local recurrence. Prospective use may aid physicians in reducing the risk of local recurrence during prostate cryoablation procedures.
Combining Proton Resonance Frequency Shift and T1-mapping Thermometry with a 3D Spiral Ultra-Short Echo Time Sequence
Authors: Chen Sheng , Gilbo Yekaterina , Sporkin Helen , Fielden Samuel , Allen Steven , Mugler John , Miller G. , Meyer Craig
Published: August 2023

Temperature monitoring plays an essential role in transcranial MR-guided focused ultrasound (tcMRgFUS) surgery for measuring thermal dose at the target. Unintended heating of the skull and nearby brain tissue is not currently monitored. By using a two-echo 3D spiral ultra-short echo time (UTE) sequence, we demonstrate a method that combines T1-mapping and proton resonance frequency (PRF) shift thermometry to simultaneously monitor skull and brain heating and validate it in an in vitro model.
Feasibility of microwave ablation using two applicators with real-time MR thermometry
Authors: Ren Liqiang , Woodrum David , Gorny Krzysztof , Felmlee Joel , Favazza Christopher , Thompson Scott , Lu Aiming
Published: August 2023

Simultaneous use of multiple applicators is desirable in MRgMWA when treating large tumors and its feasibility is investigated in phantom experiments to evaluate the impact of MW system on MR image quality and in ex-vivo experiments with porcine tissue to compare MWA procedures with one and two applicators. Relative SNR was dropped from 88.1% with one applicator activated to 54.6% with both activated, yet temperature and tissue damage maps with acceptable image quality were obtained. Simultaneous use of two MW applicators could significantly increase the treatment efficiency with a larger ablation zone when both applicators are properly selected and configured.
MAGORINO: Magnitude-only fat fraction and R2* estimation with Rician noise modelling
Authors: Bray Timothy , Bainbridge Alan , Hall-Craggs Margaret , Zhang Hui
Published: August 2023

Magnitude signal-based fitting of chemical shift-encoded data enables proton density fat fraction (PDFF) and R2* estimation where complex signal-based fitting fails or when phase data are inaccessible/unreliable, such as in multicentre studies. However, traditional magnitude-based fitting suffers from Rician noise-related bias and fat-water swaps, limiting utility. Here, we propose MAGORINO, an algorithm combining Magnitude-Only PDFF and R2* estimation with Rician Noise modelling, to address these limitations. We demonstrate that MAGORINO outperforms traditional Gaussian noise-based magnitude-only estimation through (i) reduced noise-related bias and (ii) reduced fat-water swaps. This may be valuable in multicentre studies or when phase data are otherwise inaccessible/unreliable.
Validation of a 3D MR temperature imaging sequence for use during breast magnetic resonance guided focused ultrasound treatments
Authors: Adams Samuel , Johnson Sara , Odéen Henrik , Parker Dennis , Payne Allison
Published: August 2023

This work presents a 3D MR temperature imaging (MRTI) sequence for breast MRgFUS. A 3D gradient echo with segmented echo planar imaging readout sequence with time-varying drift correction was used in female volunteers and tissue-mimicking phantoms. Temperature changes due to FUS heating in phantoms were measured with fiberoptic probes and compared to MRTI. Non-heating volunteer data was also acquired. Temperature in the phantom studies was accurate compared to FO probes with an RMSE of 1.0°C. Mean precision and accuracy of 1.05 and 1.29°C were measured in healthy volunteers. This sequence provides accurate and precise 3D temperature measurements for breast MRgFUS.