bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust STARE (Steady-state T2 And Rf Estimation) for high-resolution quantitative T2 mapping at 7T MRI
Authors: Schmidt Rita
Published: August 2023

T2 mapping can provide a valuable tool for monitoring and characterization of the tissue changes in the brain. Its implementation in 7T MRI will improve SNR and resolution, but also needs to overcome an increase in SAR and B1 inhomogeneity. We developed a Steady-state T2 And Rf Estimation (STARE) method capable to deliver T2 and RF-field maps in 7T brain imaging. This work summarizes progress towards robust high-resolution whole brain T2 mapping. The method was examined in phantoms and human imaging. Whole brain T2 maps with 1mm resolution were acquired within 3:27 minutes, sufficiently fast to be used in clinics.
Beat Phenomena in MRI - Theoretical and Experimental Description of the Impact of Mechanical Resonances on Fast Readouts
Authors: Dillinger Hannes , Kozerke Sebastian
Published: August 2023

This work highlights the mechanically resonant behaviour of MRI gradient systems when excited with an oscillating gradient, e.g. echo planar readout. Results demonstrate that a beat phenomenon can be observed in the signal phase with a frequency dependent on readout bandwidth and mechanical resonances of the system. Insights of the beat source are derived theoretically and validated experimentally. Data confirms that the beat phenomenon results in increased blurring in phase encoding direction leading to suggestions for system optimization in order to reduce the impact of the beat phenomenon.
A lightweight silent gradient axis design with integrated 32 channel receive array for fast and quiet brain imaging at 3 Tesla
Authors: Versteeg Edwin , van Uden Mark , van der Hofstad Luke , Bax Kevin , Borgo Martino , Schuth Wout , Siero Jeroen , Gosselink Mark , Klomp Dennis
Published: August 2023

The sound level in MRI can be lowered by using a silent gradient axis that adds extra soundless encoding. In this work, we present the field characteristics and first images for a silent gradient designed for a clinical 3 Tesla system. This silent gradient featured a built-in 32-channel receive coil and weighs 21 kg. The gradient field could be oscillated at 23.5 kHz and featured a linear region of 20 cm. The coil had limited interactions with the transmit B1 field and did not affect B1 homogeneity, which was showcased in phantom and in-vivo images.
Fasciculus Axonal Connective Tissue (FACT) Mapping of Porcine Optic Nerve for Accurate Connectome Mapping at Viable Cost
Authors: Pathak Sudhir , Wu Yijen , Gorantla Vijay , Zor Fatih , Kulahci Yalcin , Watson Alan , Zhao Yongxin , Schneider Walter
Published: August 2023

Accurate brain connectome mapping requires tracking fasciculus bundles of axons within tracts. In a porcine optic nerve harvested tissue, we optimized/tested MRI structural and diffusion imaging to demonstrate following fasciculi within the optic tract. On a 7T Bruker magnet, we can clearly identify fasciculus boarders and diffusion paths providing 29 micron precision MRI with clear tissue differentiation. We found that axons travel with no evidence of crossing fasciculi walls. This suggests Fasciculus Axonal Connective Tissue (FACT) imaging can provide full mapping of connectivity between cortical sources supporting comprehensive accurate mapping of connectivity in large mammal tract systems at viable cost.
Model Pruning for Generalisability Across MRI Imaging Sites
Authors: Dinsdale Nicola , Jenkinson Mark , Namburete Ana
Published: August 2023

We propose an algorithm to simultaneously prune and train CNNs, leading to networks which have increased generalisability across imaging sites. Through segmentation of data from the ABIDE dataset, we show that through reducing the number of parameters in the network throughout training, we are able to reduce model overfitting, creating a model which is more robust to expect image variations across scanners. We also introduce a novel Targeted Dropout algorithm, which aids the process of model pruning. We demonstrate the approach on a UNet architecture, the basis of nearly all segmentation approaches across medical imaging.
Neuroimaging Findings & Neurological Symptoms in COVID-19 Patients with & without Cancer: A Retrospective Multi-Center Observational Study
Authors: McCarthy Lily , Khegai Oleksandr , Goldstein Jonathan , Belani Puneet , Pawha Puneet , Kihira Shingo , Mathew Brian , Gururangan Kapil , Hao Qing , Singh Anuradha , Navis Allison , Delman Bradley , Jette Nathalie , Balchandani Priti
Published: August 2023

COVID-19 is known to result in neurological manifestations which sometimes correlate with neuroimaging abnormalities. Understanding these abnormalities requires further systematic study. We undertook a retrospective analysis of 60 MRIs from hospitalized COVID-19 patients (20 intubated, 20 non-brain cancer, and 20 non-intubated/non-cancer) with neurological manifestations. Neuroimaging showed non-infarct parenchymal T2/FLAIR signal hyperintensities (26.7%), acute/subacute infarcts (25%), microhemorrhages (21.7%), chronic infarcts (18.3%), chronic macrohemorrhages (10%), and acute macrohemorrhages (6.7%). Common neurological symptoms were confusion/encephalopathy/delirium (70%), generalized weakness (38.3%), and impaired responsiveness/coma (38.3%). Thus, COVID-19 may be associated with neuroimaging abnormalities. Differences in abnormalities were seen based on permutations of cancer and intubation.
A Fast T2-weighted Approach for Prostate Imaging using non-Cartesian GRAPPA and Spiral TSE readout
Authors: Ahad James , Jiang Yun , Gulani Vikas , Seiberlich Nicole
Published: August 2023

In-gantry prostate biopsy relies on repeated time-consuming T2-weighted TSE imaging for needle guidance. Reducing the acquisition time for this scan has been challenging due to the spatial resolution and field-of-view requirements of these images, in addition to susceptibility and off resonance artifacts sources common to pelvic imaging. This work proposes a non-Cartesian GRAPPA approach with a short spiral in-out TSE readout to reduce acquisition time for needle guidance images. Comparisons of in vivo Cartesian and spiral TSE images with 300mm FOV, 1.17x1.17mm2 resolution, and 3mm slice thickness acquired in 61s and 8s respectively, are shown.
Identification of ’black hole’ T1 hypointense lesions using different intensity thresholds on gradient-echo T1w MRI
Authors: Wiggermann Vanessa , Martinez Mie Arnau , Merhout Jasmin , Christensen Jeppe Romme , Blinkenberg Morten , Sellebjerg Finn , Lundell Henrik , Siebner Hartwig
Published: August 2023

Black holes (BHs), T1 hypointense lesions, are known predictors of multiple sclerosis disease severity, however, their identification is strongly intensity dependent. As traditional spin-echo T1 scans are being replaced by 3D gradient-echo images, we need to understand how hypointense lesions on these images compare. We assessed whether an intensity threshold for MPRAGE images exists that would allow to match spin-echo black hole definitions. Simple thresholding was only able to reproduce black hole segmentations to an intermediate degree.
Magnetisation transfer saturation and MTR in multiple sclerosis: sensitivity to longitudinal change and clinical disability
Authors: York Elizabeth , Meijboom Rozanna , Thrippleton Michael , Kampaite Agniete , Hernandez Maria Valdes , Connick Peter , Chandran Siddharthan , Hunt David , Waldman Adam
Published: August 2023

Myelin-sensitive magnetisation transfer saturation (MTsat) corrects magnetisation transfer ratio (MTR) signal variance, accounting for T1 recovery and B1 inhomogeneities, but its validity as a longitudinal imaging marker in multiple sclerosis (MS) is not yet clear. Here, we examine longitudinal change in cerebral MTsat and MTR in a cohort of people with newly diagnosed MS (n=62). MTsat, but not MTR, decreased in normal-appearing white matter over one year and was associated with clinical disability progression. In white matter lesions, both MTsat and MTR increased longitudinally. We conclude that MTsat is more sensitive to subtle myelin damage over time than MTR.
Brain tissue segmentation on 3D-FLAIR weighted images in multiple sclerosis
Authors: Noteboom Samantha , Steenwijk Martijn , van der Nederpelt David , Strijbis Eva , Moraal Bastiaan , Barkhof Frederik , Geurts Jeroen , Caan Matthan , Vrenken Hugo , Schoonheim Menno
Published: August 2023

Conventional brain segmentation approaches typically require high resolution 3D-T1 weighted images, which are often unavailable in clinical multiple sclerosis (MS) protocols. Recently, SynthSeg was released which allows 3D-FLAIR to be used for segmentations. This study compared segmentation on 3D-FLAIR with SynthSeg to segmentation in the same patients on 3D-T1 (SynthSeg, FastSurfer and SAMSEG). Brain segmentation was performed on 100 patients with 3D-T1 and 3D-FLAIR images from research and clinical datasets. ICC results showed good comparability for brain tissue, ventricle and grey matter assessments in research data. In clinical data only good comparability was found for ventricle segmentation.
Spinal Cord Lesions and Brain Grey Matter Atrophy Predict 5-Year Disease Worsening in Multiple Sclerosis: A Multicentre Study
Authors: Valsasina Paola , Rocca Maria A. , Meani Alessandro , Storelli Loredana , Gobbi Claudio , Zecca Chiara , Barkhof Frederik , Schoonheim Menno , Strijbis Eva , Vrenken Hugo , Gallo Antonio , Bisecco Alvino , Ciccarelli Olga , Yiannakas Marios , Rovira Alex , Sastre-Garriga Jaume , Palace Jacqueline , Matthews Lucy , Gass Achim , Eisele Philipp , Lukas Carsten , Bellenberg Barbara , Margoni Monica , Preziosa Paolo , Filippi Massimo
Published: August 2023

Aim of this study was to evaluate the independent role of brain and cervical cord damage in predicting 5-year clinical disability worsening in a multicentre cohort of multiple sclerosis patients. Results showed that cortical atrophy and spinal cord damage, together with baseline disability and progressive disease phenotype, independently predicted 5-year disability worsening (C-index=0.81). Older age, higher clinical disability and cord lesion number independently predicted conversion to a progressive disease phenotype (C-index=0.91). Focal spinal cord lesions and cortical atrophy had also a role in predicting clinically-relevant disability milestones at 5 years.
COMPARISON OF CONVENTIONAL AND ACCELERATED 4D FLOW MRI ON A FLOW PHANTOM
Authors: Garreau Morgane , Puiseux Thomas , Moreno Ramiro , Toupin Solenn , Giese Daniel , Mendez Simon , Nicoud Franck
Published: August 2023

Fully-sampled and accelerated (GRAPPA R=3 and compressed sensing R=7.6) 4D Flow MRI acquisitions were compared for velocity profiles, flow rates and peak velocities in a rigid cardiovascular phantom under complex pulsatile flow conditions. Compatible CFD simulations were performed under the same flow conditions as a complementary modality. Good agreement was found between the three MR techniques, but discrepancies relative to the principle of mass conservation were noticed. Even though CFD presents some limitations as well, it appears to be a useful tool to investigate these differences.
The Open Science Initiative for Perfusion Imaging (OSIPI): ASL Code Library
Authors: Álvarez María Mora , Zhao Li , Dolui Sudipto , Taso Manuel , Wang Yiming , Zhou Limin , Wang Ze , Adebimpe Azeez , Mutsaerts Henk , Madhuranthakam Ananth
Published: August 2023

Task force 2.2 of the Open Science Initiative for Perfusion Imaging (OSIPI) is developing a library of open-source functions, and scripts for Arterial Spin Labeled (ASL) perfusion imaging preprocessing and analysis. This is aimed for developers of ASL perfusion methods looking for specific functionalities or development templates, or who want to share their own in-house code with others. The collected source code will be organized and documented so as to support the open library development.
Hybrid image and k-space deep learning reconstruction exploiting spatio-temporal redundancies for 2D cardiac CINE
Authors: Xu Siying , Krumm Patrick , Lingg Andreas , Qi Haikun , Hammernik Kerstin , Küstner Thomas
Published: August 2023

Cardiac CINE MR imaging allows for accurate and reproducible measurement of cardiac function but requires long scanning times. Parallel imaging and compressed sensing (CS) have reduced the acquisition time, but the possible acceleration remained limited. Deep learning-based MR image reconstructions can further increase the acceleration rates with improved image quality. In this work, we propose a novel network for retrospectively undersampled 2D cardiac CINE that a) operates in image and k-space domain with interleaved architectures and b) utilizes spatio-temporal filters for multi-coil dynamic data. The proposed network outperforms CS and some other neural networks in both qualitative and quantitative evaluations.
Characterisation and Removal of Slice Dependent Artifacts in EPI Phase Images
Authors: Nassar Jannette , Kiersnowski Oliver , Fuchs Patrick , Shmueli Karin
Published: August 2023

Although EPI phase images are useful (e.g. for Quantitative Susceptibility Mapping), they often contain phase inconsistencies in the slice-select direction which persist and can degrade QSM results. Here, we analysed three EPI datasets in healthy volunteers to characterise these phase inconsistencies and understand whether they occur or interact with interleaved or sequential slice acquisition order. We characterised a ~2Hz cryogen pump artifact in sequential data and slice-to-slice phase jumps in interleaved data. We modified a previously proposed QSM processing pipeline, including 2D (VSHARP) and 3D (PDF) background field removal that removed all through-slice artifacts observed.
The Effect of Label Crossing the Blood-CSF barrier on Partial Volume Correction: source of error or opportunity for quantification?
Authors: Petitclerc Leonie , Hirschler Lydiane , Asllani Iris , van Osch Matthias
Published: August 2023

Partial volume correction in ASL typically neglects CSF signal, however we have recently shown that some labeled signal crosses the blood-CSF barrier at a measurable level. Here we show the effect of including CSF in PVC, in simulated and in-vivo data. CSF-PVC reduced error on GM perfusion by ~10% in simulated data, with higher error when more CSF is present (including at longer LD and PLD). The difference between CSF-PVC and non-CSF-PVC GM signal in vivo was also ~10%. Comparing PVC signal in CSF to long-TE ASL signal suggests that BCSFB characterization may be possible without the acquisition of ultra-long-TE.
Refined feature selection method for the depiction of pathology by texture analysis – Applicated on MR images of intervertebral discs fissures
Authors: Waldenberg Christian , Eriksson Stefanie , Hebelka Hanna , Brisby Helena , Lagerstrand Kerstin
Published: August 2023

Texture analysis combined with attention mapping has the potential to identify the position of pathology normally not visible in MR images by exploiting inter-pixel relationships in magnetic resonance (MR) images. However, as pathology can influence adjacent tissue, the features used to identify the position of the pathology have to be selected with care. Here we present an easily implemented method that efficiently selects texture features that are only sensitive to the pathology and can improve the localization of pathology even when not visible in MR images.
Predicting the arithmetic mean radius from the MRI-visible axon radius
Authors: Mordhorst Laurin , Ashtarayeh Mohammad , Morozova Maria , Papazoglou Sebastian , Fricke Björn , Streubel Tobias , Jäger Carsten , Rusch Henriette , Starke Ludger , Gladytz Thomas , Tasbihi Ehsan , Niendorf Thoralf , Weiskopf Nikolaus , Morawski Markus , Mohammadi Siawoosh
Published: August 2023

The axon radius is a main determinant of the conduction velocity of action potentials. Robust, MRI-based axon radius estimation is sensitive to a tail-weighted estimate of the ensemble-average axon radius, i.e., the effective axon radius ($$$r_{\text{eff}}$$$). It is unclear how $$$r_{\text{eff}}$$$ translates into the arithmetic mean axon radius ($$$r_{\text{arith}}$$$), which may be more indicative of the conduction velocity than $$$r_{\text{eff}}$$$. We investigate the feasibility to predict $$$r_{\text{arith}}$$$ from $$$r_{\text{eff}}$$$ using linear regression on high-resolution, large-scale light-microscopy images of a human corpus callosum sample and validate this linear relationship with microscopy and diffusion-weighted MRI images of another human corpus callosum sample.
3D EPI sequence for indirect detection of hyperpolarized [2-13C]lactate with J-coupling artifact correction
Authors: Blazey Tyler , von Morze Cornelius
Published: August 2023

Imaging of hyperpolarized (HP) 13C magnetization is typically done using direct detection of the 13C signal. However, indirect 1H-based detection via J-coupled protons has the advantage of reducing gradient requirements and enhancing sensitivity, as well as practical advantages. We have developed an INEPT-based EPI sequence, which we tested by acquiring 3D images of a 13C formate phantom after transfer of thermal polarization from 1H to 13C. We also tested a novel deconvolution method to correct ghosting artifacts introduced in EPI images by J-coupling. These methods will be translated into in vivo HP imaging experiments in the next phase of research.
Signal prediction in echo dimension of multi-echo gradient echo using multi-layer seq2seq model
Authors: Yun Jisu , Lee Seul , Park Muyul , Kim Dong-Hyun
Published: August 2023

The mGRE(multi-echo gradient echo) sequence has previously been used for MWF(Myelin water fraction) imaging. Such mGRE observes signal decay by obtaining multiple echo signals, but scan time increases as more echoes are obtained. To solve this trade-off, we developed a deep learning model based on a LSTM model that can reduce scan time by predicting the later echoes using only the early echoes. Looking at the in vivo results and various performance test, our network has lower RMSE and higher PSNR than NLLS(Non-linear least squares), a conventional fitting algorithm.
On the impact of heart rate and relaxation on SNR of hyperpolarized 13C pyruvate metabolic imaging of the human heart
Authors: Traechtler Julia , Fuetterer Maximilian , Hoh Tobias , Albannay Mohammed , Dounas Andreas , Kozerke Sebastian
Published: August 2023

In hyperpolarized 13C MRI, the achievable base SNR depends on the T1 relaxation of pyruvate in blood. Heart rate dependency on the resulting SNR is examined using simulations and exemplarily shown on human data of the heart. Measured T1 and T2 values at 1.5T and 3T of hyperpolarized 13C pyruvate in blood are reported. The results indicate that for a range of pyruvate concentrations, T2 remains >6s and hence T2* is primarily determined by field inhomogeneities. T1 is reduced at lower concentrations, and therefore heart rate plays a decisive role for the achievable SNR. Exemplary in-vivo data illustrate these findings.
Mapping of apparent Intra- and extra-myocellular lipid content using spiral spectroscopic imaging and diffusion imaging at 3T
Authors: Naëgel Antoine , Viallon Magalie , Karkouri Jabrane , Troalen Thomas , Moulin Kevin , Croisille Pierre , Ratiney Hélène
Published: August 2023

Exploring spatial distribution of intra- and extramyocellular lipids linked to the orientation of muscle fibers is complex. We used a magnetic resonance spectroscopic imaging (MRSI) technique with a spiral encoding of k-t space and diffusion imaging tractography at 3T to reveal possible concomitant factors. The IMCL preponderance index, exploiting the spectroscopic dimension and proposed in this study, highlights interesting and relevant patterns in some calf muscle heads.
Multi-Echo MR-Encephalography using Spherical Stack of Spirals Trajectories
Authors: Barghoorn Antonia , Riemenschneider Bruno , Yang Wenchao , Hennig Jürgen
Published: August 2023

MREG allows very fast measurement of physiological signal changes at 100 ms acquisition time per volume. In order to investigate BOLD and non-BOLD contributions to the observed signal variations we have implemented an interleaved measurement scheme based on signal readout with two different echo times (15 and 36 ms). The interleaved implementation with alternating echo times increases the acquisition time to 200 ms, which still allows to investigate BOLD vs. non-BOLD signal changes at frequencies up to ±2.5 Hz. Preliminary measurements demonstrate the feasibility of ME-MREG in detecting both neuronal activations and resting-state functional connectivities.
Differentiating Skeletal Muscle Fiber Composition Using a Bi-Fractal Model of Resting-State Muscle BOLD
Authors: McGillivray Joshua , Kumbhare Dinesh , Noseworthy Michael
Published: August 2023

Lower leg resting-state BOLD images (n=8 males, 4 endurance, 4 power athletes), were acquired after 30min of rest, allowing for blood-flow normalization. BOLD images were motion corrected and the gastrocnemius and soleus manually segmented using an anatomical reference for their differing twitch fibre profiles. Voxel-wise BOLD mono- and bi-fractal dimension were computed using the scaled windowed variance approach, with linear detrending, removing scanner induced low-frequency variations. The bi-fractal dimension was significantly different between endurance and power groups in both muscles. Specific bi-fractal components more readily distinguished soleus and gastrocnemius for the endurance (I) and power (II) group, when at rest.
Skeletal muscle energetics and function in sickle cell disease murine model: a synergetic effect of hydroxyurea and endurance training?
Authors: Michel Constance , Messonnier Laurent , Giannesini Benoit , Bendahan David
Published: August 2023

In sickle cell disease (SCD), hydroxyurea can increase foetal haemoglobin production and restore oxygen-carrying capacity of patients. As endurance training is also known to improve muscle aerobic capacity, one can wonder whether hydroxyurea and endurance training can have a synergetic effect. Townes mice (model of SCD) have been trained with and without hydroxyurea for 8 weeks. Muscle energetics and function were assessed in response to a rest-stimulation-recovery protocol before and after interventions. While training increased force production, mitochondrial function was improved when training was combined to hydroxyurea supplementation. In SCD, this combination would have a synergetic effect in muscle energetics.
Ventilation Defect Synthesis in Hyperpolarized 129Xe Ventilation MRI to Accelerate Training of Segmentation Models
Authors: Leewiwatwong Suphachart , Lu Junlan , Zhang Jesse , Mummy David , Dummer Isabelle , Yarnall Kevin , Wang Ziyi , Driehuys Bastiaan
Published: August 2023

Quantification of 129Xe MRI relies on accurate segmentation of the thoracic cavity. This segmentation could potentially be performed directly on the 129Xe ventilation image using an automated convolutional neural network, but this task is challenging, especially in cases where peripheral ventilation defects obscure the lung boundary. Currently, overcoming this obstacle requires large, diverse training datasets created by time-consuming manual segmentation. Here, we demonstrate the use of a generative Pix2Pix model to synthesize both 129Xe images with defects, and corresponding segmentation masks. We then test the effects of this additional training data on the performance of an existing U-net segmentation algorithm.
The Value of 3D arterial spin labeling in early diagnosis and prognostic grouping of Full-Term neonatal hypoxic-ischemic encephalopathy
Authors: Liu Chang , Yong Zhang
Published: August 2023

3D-ASL technology can reflect cerebral blood flow perfusion status,which is helpful for early diagnosis of HIE.The predictive value of ASL for the prognosis of full-term HIE patients is higher than that of DWI.
Towards fast but accurate velocity quantification with 3D ultra-short TE phase contrast imaging
Authors: Degenhardt Katja , Aigner Christoph , Schmidt Simon , Kratzer Fabian , Müller Max , Nagel Armin , Schulz-Menger Jeanette , Schmitter Sebastian
Published: August 2023

The aim of this work is to develop and investigate an accurate sequence for MR flow quantification. We utilized a 3D ultra-short echo time (UTE) flow sequence to minimize the displacement artifact that frequently occurs in MR flow imaging. In UTE acquisitions, the position is encoded at the beginning of the readout. Thus, the time difference between velocity encoding and spatial position encoding is minimized. This leads to an improved accuracy of the velocity quantification. The sequence was tested and validated against a reference sequence and a conventional 4D flow sequence in a flow experiment in vitro at 3T.
U-Net-based deep convolutional neural network for detection of superparamagnetic drug-eluting particles used for liver chemoembolization
Authors: LI NING , Tous Cyril , Fei Phillip , Dimov Ivan , Lessard Simon , Häfeli Urs , Martel Sylvain , Tang An , Soulez Gilles
Published: August 2023

Magnetic steering of superparamagnetic drug-eluting particles (SMDEPs) loaded with anti-tumor drugs across hepatic arteries is a promising technique to perform segmental liver embolization for patients with hepatocellular carcinomas (HCCs). These aggregates (20 ± 6 SMDEPs) are sequentially released with a specially designed injector through a catheter in the proper hepatic artery of a swine placed in an MRI. Manual segmentation was previously done to localize and count the particles (volume of the artifact) in each lobe. We propose to train a U-net over this pre-existing database. Dice similarity coefficient, accuracy, and precision were respectively 99.1%, 98.3%, and 84.6%.
Impact of Diffusion Signal Harmonisation on Voxel-Wise Analysis of Mild Traumatic Brain Injury
Authors: Winzeck Stefan , Richter Sophie , Pinto Maira Siqueira , Kornaropoulos Evgenios , Newcombe Virginia , Glocker Ben , Menon David , Correia Marta
Published: August 2023

The comparison of voxel-wise regression analysis of a multi-centre diffusion MRI study showed that similar results could be achieved regardless of whether prior data harmonisation was applied or not. However, harmonisation had a positive impact on increasing the effect size found between mild traumatic brain injury patients and controls.
A Novel PET Optimized Head Neck Coil for 3T Simultaneous MRPET System
Authors: Stickle Yun-Jeong , Giancola Mark , Follante Clyve Konrad , Stickle Thomas , Robb Fraser , Blahnik Holly , Yang Tae-Young
Published: August 2023

A PET optimized 21- Element Head Neck coil is described for acquiring high-sensitivity MR (Magnetic Resonance) images and good quality PET images of head/neck, carotids, and cervical spine at 3 Tesla simultaneous MR/PET system. This Head Neck prototype2 coil has been optimized to minimize the interference with -ray detection of the PET without sacrificing MR image quality. In this study, we developed a foam technology to replace the rigid plastic coil formers, optimized arrangement of components (internal cables, internal cable baluns, feed boards and decoupling boards) and introduced new mechanical fastener and snap features.
Effects of Sleep on perivascular space in healthy population
Authors: Shih Nien-Chu , Lincoln Karen , Sepehrband Farshid , Choupan Jeiran
Published: August 2023

The perivascular space (PVS) has been reported to clear Amyloid-β (Aβ) and metabolic wastes during sleep. However, the relationship between sleep and PVS in a healthy cohort is still unclear. We investigate the association between PVS and sleep across different age groups. We found that the effect of sleep on PVS volume varies in the young and older population.
Optimization of an MRI protocol for non-contrast saccule and utricle visualization at 1.5T
Authors: Sanchez Alba Iruela , Prevost Valentin , Garcia Alicia Palomar , de Graaf Wolter , Triaire Bruno
Published: August 2023

This study evaluates the feasibility of different approaches for the visualization of endolymphatic content in inner ear structures on 1.5T MR systems without the need of contrast injection. The results show that using an optimized high-resolution 3D T2w sequence combined with DLR-based denoising tools it is possible to visualize the utricle and saccule structures on healthy volunteers. The next step will be testing this technique on patients with endolymphatic hydrops.
BOLD MRI Perfusion in Peripheral Skeletal Muscle: Revealing the cuffing duration dependency
Authors: Eriksson Stefanie , Arvidsson Jonathan , Mohammad Suhela Abubakar , Johansson Edvin , Lagerstrand Kerstin
Published: August 2023

This study demonstrates the cuffing duration dependence of BOLD T2*-time curve parameters in peripheral skeletal muscle in the calf. This was made possible by the repeated measurements of healthy individuals using two different cuffing paradigms. The cuffing paradigms consisted of an ischemic period induced by cuffing of the thigh for 1.5 or 5 minutes, as well a 5 minute period of reactive hyperaemia. Systematic comparison of derived parameters was done from a descriptive representation of the T2* time curve.
Quantification of regional cerebral blood flow using diffusion imaging with phase-contrast (DIP)
Authors: Nambu Genki , Ohno Naoki , Miyati Tosiaki , Sugita Fumiki , Makino Yuki , Ikeda Momoka , Alperin Noam , Gabata Toshifumi , Kobayashi Satoshi
Published: August 2023

Perfusion-related diffusion coefficient (D*) in intravoxel incoherent motion analysis is closely correlated with the regional cerebral blood flow (rCBF). However, the D* is only a semiquantitative relative value of rCBF, which makes absolute rCBF quantification challenging. To solve this problem, we developed a novel method of diffusion imaging with phase contrast (DIP), in which the total CBF (tCBF) from phase-contrast (PC)-MRI was used to convert the perfusion-related parameters in the brain to absolute rCBF. Using this method, we measured rCBF in gray matter and white matter. Each value was consistent with literature values assessed using [15O]-water positron emission tomography.
Comparison of MR diffusion based tractography methods for reconstruction of the facial nerve in pre-operative vestibular schwannoma
Authors: O'Brien Caitlin , Touska Philip , Gabriel Elizabeth , Shuaib Haris , Welsh Karen , Connor Steve
Published: August 2023

Four DWI tractography acquisitions are trialled across 13 pre-surgical patients with vestibular schwannomas: single shell EPI, ZOOMit, RESOLVE, & multi-shell RESOLVE, with an aim to reconstruct the path of the facial nerve. Data is analysed using MRtrix using multi-shell multi-tissue constrained spherical deconvolution (MSMT-CSD) and the probabilistic iFOD2 algorithm. The best reconstruction was achieved using a 30 direction multi-shell (b = 0, 300, 1000 s/mm2) RESOLVE acquisition scheme.
Quantification and visualization of aneurysm treatment outcome with signal enhancement on Black Blood MRI.
Authors: Pravdivtseva Mariya , Wodarg Fritz , Korte Jana , Berg Philipp , Hövener Jan-Bernd , Jansen Olav , Larsen Naomi
Published: August 2023

Intracranial aneurysm is a life-threatening disease that can be treated with flow-modulating devices (FMDs) by reducing aneurysm blood flow. Aneurysms might rupture after treatment, thus biomarker of successful treatment is needed. Flow MRI can detect flow reduction, however, it is impaired by metal artifacts from FMDs. Black-blood (BB) MRI is less sensitive to metal artifacts and often results in poor slow-flow suppression. We hypothesize that BB contrast changes after aneurysm treatment. Here, after placing FMDs in 3D-printed aneurysm models, an enhanced signal was found on BB MRI, associated with reduced aneurysmal flow after flow modulation and thus possible treatment success.
Towards a personalized MRgFUS treatment for tremor disorders: A study on the number of ablations using deep learning and structural connectivity
Authors: Tang Zihao , Cabezas Mariano , Kyle Kain , D'Souza Arkiev , Tisch Stephen , Jonker Ben , Barnett Yael , Maamary Joel , Maller Jerome , Barnett Michael , Cai Weidong , Wang Chenyu
Published: August 2023

Disabling tremor is the most common symptom of tremor-dominated Parkinson’s disease (PD) patients. Recently, MR guided focused ultrasound (MRgFUS) has been applied in the clinical environment to treat tremor. However, patients can have different treatment responses to the ablation. Tremor suppression can be observed on some patients after ablating the ventral intermediate nucleus (Vim), while others require further ablations. To provide a tailored treatment, a deep learning technique is introduced in this work to predict whether a subject undergoing MRgFUS will respond to a single ablation in the VIM or require additional lesioning in other regions.
Influence of Glycosaminoglycans on the Transmetallation and Transchelation Kinetics of Gadolinium from GBCAs in the Presence of ZnCl2
Authors: Werner Patrick , Schuenke Patrick , Taupitz Matthias , Schröder Leif
Published: August 2023

Relaxation rates in aqueous solutions containing 30-100 µM heparin as well as 150 µM GBCA were measured as a function of time. Different ZnCl2 stimuli with concentrations between 0.125-4 mM were used as competing ions that initiate a transmetallation and a transchelation process of the Gd3+ ion from GBCAs to glycosaminoglycans. The time resolved relaxometry measurements indicate that glycosaminoglycans play a concentration-dependent double role as competing chelator structures. They foster the thermodynamic instability of intact GBCA by sequestering Gd3+ from the contrast agent but simultaneously interact with competing ions and thus cause a reduced kinetic instability.
Traumatic spinal cord injury – transition from a focal lesion to widespread neurodegeneration: Lessons from 60-month observational data
Authors: Emmenegger Tim , Pfyffer Dario , Schading Simon , Thompson Alan , Ziegler Gabriel , Ashburner John , Friston Karl , Weiskopf Nikolaus , Curt Armin , Freund Patrick
Published: August 2023

Traumatic spinal cord injury (SCI) triggers a cascade of neurodegenerative events across the neuroaxis. The trajectories of lesion characteristics and brain and spinal cord macro-and microstructural changes were analysed over five years in 23 SCI patients and 21 healthy controls. Initially, SCI patients showed higher volume and iron content in the spinal cord which decreased over time. They showed lower myelin-sensitive MTsat values in the dorsal column and cortex which also decreased over time and were associated with acute lesion characteristics. These observations illustrate the widespread and progressive neuroplastic processes after SCI, its magnitude being predicted by acute lesion characteristics.
Automatic spinal cord segmentation in pediatric MR images
Authors: Blanc Colline , Shahrampour Shiva , Mohamed Feroze , De Leener Benjamin
Published: August 2023

Segmentation of the spinal cord is an essential process for the accurate delineation of spinal cord structures. However, it is a long process and automatic segmentation tools are not adapted to segment the pediatric spinal cord. We therefore developed a tool mixing a neural network and a deterministic method to overcome the limitations. We succeeded in obtaining a segmentation with a dice coefficient of 0.86 on a patient with a spinal cord injury (SCI).
PREFUL-MRI evaluation of dynamic hyperinflation induced by metronome-paced tachypnea in COPD patients
Authors: Müller Robin , Klimeš Filip , Voskrebenzev Andreas , Behrendt Lea , Kaireit Till , Crisosto Cristian , Zubke Maximilian , Prince Martin , Cooper Christopher , Barr R. , Hohlfeld Jens , Vogel-Claussen Jens
Published: August 2023

Metronome-paced tachypnea (MPT) is a technique where a patient breathes with a fixed frequency (40 breaths / minute). MPT induces dynamic hyperinflation and allows investigation of potential stress-driven effects on ventilation parameters. Fourteen patients with chronic obstructive pulmonary disease (COPD) underwent phase-resolved functional lung (PREFUL) MRI with 2D coronal lung MR images acquired during normal tidal breathing (NTB) and MPT. Compared to NTB, ventilation defect percentages increased in COPD patients during MPT. Thus, MPT in conjunction with PREFUL-MRI will be further investigated as a possible sensible ventilation test for COPD patients.
Automated subject-specific pixels selection for improved image reconstruction in free-running coronary MRA using SIMBA
Authors: Romanin Ludovica , Roy Christopher , Prsa Milan , Rutz Tobias , Tenisch Estelle , Stuber Matthias , Piccini Davide
Published: August 2023

This work proposes an automated subject-specific individual pixels selection as an alternative to a fixed coil selection for the initialization of the input data to a similarity-driven multi-dimensional binning algorithm (SIMBA) for free-running motion-suppressed whole-heart acquisitions. By selecting timeseries with a high low-frequency energy content, we include only pixels with respiratory and cardiac information. Compared to the original method, this leads to a more accurate choice of end-expiration and diastolic phases for the reconstruction of sharp whole-heart and coronary images. Moving forward, the method needs to be refined, optimized and tested to further improve the image quality.
Accelerated whole-heart mDixon coronary MRA with a deep learning constrained CompressedSENSE: a feasibility study
Authors: Wu Xi , Sun Jiayu , Zhang Xiaoyong , Wu Zhigang
Published: August 2023

Currently, modified dixon (mDixon) gradient echo sequence is widely used for respiratory navigated whole-heart coronary magnetic resonance angiography (MRA) for the evaluation of coronary anatomy and abnormalities. However, the main drawback of this approach is that the scan time is longer and prone to interference with motion artifacts. In this study, we investigated the utility of whole-heart coronaryMRA using accelerated mDixonwith compressed sensing (CS) and artificial intelligence(AI) technologies at 3Tesla. The initial results showedtheCS-AI mDixontechnique has potential to be the most viable alternative to enhance the clinical workflow of coronary MRA.
Balanced-force shim system for correcting field inhomogeneities due to implanted cardioverter-defibrillators (ICDs): validation in phantoms
Authors: Schmidt Ehud , Hrovat Mirko , Halperin Henry , Kolandaivelu Aravindan
Published: August 2023

A resistive-shim system was constructed to correct the >100ppm magnetic-field inhomogeneity caused by implanted ICDs, which leads to signal loss and blurring in cardiac MRI. A plastic platform, held to the MRI stretcher, allows human-subject insertion, and holds a sensitive 720 Ampere*turns dipole-approximating shim-coil on a movable-fixture above the chest. Shim-coil is electronically decoupled from gradients and body-coil-RF. ICD field-inhomogeneity is measured with B0 mapping, and a correction field computed (shim-coil-center-location, DC-current-intensity). Shim-coil is moved to shim-coil-center-location, and a power-supply sends DC-current to the shim-coil. System was tested on phantoms overlaid with ICDs and corrected >75ppm inhomogeneity over 50x50x50mm3 FOV.
DCE-MRI kinetic models for measuring subtle blood-brain barrier leakage– the importance of modelling finite interstitial volume fraction
Authors: Kozár Martin , Al-Bachari Sarah , Parker Geoff , Parkes Laura , Dickie Ben
Published: August 2023

The Patlak model is commonly applied to brain DCE-MRI to quantify subtle blood-brain barrier permeability. This is based on existing evidence showing the Patlak model provides the optimal fit compared to other candidate models, including the extended Tofts model (Heye, Thrippleton et al. 2016). In this study, we compared five different tracer kinetic models in data with higher temporal resolution and determined that models which assume finite interstitial volume (ve) (e.g. extended Tofts) consistently outperform models that assume infinite ve (e.g. Patlak), particularly in gray matter.
Age-related decline of glutathione: a magnetic resonance spectroscopy study in 180 elderly participants
Authors: Michels Lars , Treyer Valerie , Gietl Anton , Tuura Ruth O’Gorman
Published: August 2023

Glutathione (GSH) is a brain marker for oxidative stress, which has previously been associated with brain amyloidosis and memory decline. However, to date no study has examined the link between GSH and beta-amyloid in a large cohort of elderly participants. Using simultaneous PET/MRS, we assessed amyloid deposition with amyloid-PET and GSH with MEGAPRESS, in a cohort of 134 healthy elderly and 46 mild cognitively impaired participants. GSH declined with age and showed sex differences, but no significant association between GSH and amyloid status was observed
How can we reliably mitigate flip angle and fibre orientation dependence in MPM-based R2* estimation at 7T?
Authors: Milotta Giorgia , Corbin Nadège , Lambert Christian , Lutti Antoine , Mohammadi Siawoosh , Callaghan Martina
Published: August 2023

The apparent transverse relaxation rate ($$$R_{2}^{*}$$$) is influenced by biological features, e.g. iron and myelin content. However confounding factors, such as flip angle (α) and fibre orientation dependence, hinder interpretation. Multi-α data acquired as part of a comprehensive multi-parameter mapping approach can be used to mitigate these confounds. Here we explored how best to do so in vivo at 7T while additionally considering reproducibility. The ESTATICS approach, which assumes a common decay across flip angles, reduced these dependencies. $$$\hat{R_{2}^{*}}$$$, the α-independent component of a heuristic linear model, reduced both dependencies further but was less reproducible than ESTATICS.
A Cross-Species Approach for Noninvasive in Vivo Tracking of Neutrophil Dynamics upon Cardiovascular Injury by 1H/19F MRI
Authors: Bouvain Pascal , Temme Sebastian , Grandoch Maria , Flögel Ulrich
Published: August 2023

Intravenous 19F tracer application for in vivo labelling of neutrophils prior to injury allowed the non-invasive 3D visualization of neutrophils within their different hematopoietic niches over the entire body and the subsequent monitoring of their egress into affected tissues. Stimulated murine/human neutrophils exhibited enhanced labelling which could be exploited as an in vivo readout for their activation state in both sterile and nonsterile cardiovascular inflammation. In summary, the present study demonstrates that both human and murine neutrophils can be specifically targeted to track their dynamic trafficking by non-invasive 1H/19F MRI in vivo.
Portable, Low-Field MRI for Evaluation of the Knee Joint
Authors: Watchmaker Jennifer , Xia Ding , Dayan Etan , Corcuera-Solano Idoia , Ngeow Justin , By Samantha , Chen Gang , Kaye Elena , Pitts John , O'Halloran Rafael , Fayad Zahi , Huang Mingqian , Feng Li
Published: August 2023

In this work, we present results of knee imaging using a portable, point-of-care MRI system in healthy subjects and subjects with knee pathology. To the best of our knowledge, this is the first reported results for knee imaging using the portable Swoop MRI system, a portable 0.064 T MRI scanner. The low-field images show good performance in visualizing the knee joint, and there was not a significant difference in the readers’ ability to evaluate the anatomic structures.
6-Minute Turbo Spin Echo MRI of the Elbow Using Combined Simultaneous Multi-Slice and Parallel Imaging Acceleration
Authors: Akkoc Erol , Fritz Jan , Zhang Hoi Cheung
Published: August 2023

Elbow MRI contributes essential information in acute and chronic elbow injuries. Elbow MRI is ideally obtained in the superman position (prone position with elbow extended, arm elevated above the head, and hand pronated); however, this position can be challenging for patients due to injury-related pain and positioning-related discomfort. To shorten the exam time and reduce patient discomfort, we developed a 4-fold accelerated 5-sequence 6-minute clinical MRI protocol using combined simultaneous multi-slice and parallel imaging acceleration of turbo spin echo sequences. In this study, we compared the image quality of our conventional and novel accelerated elbow MRI protocols.
Quantification of grey matter sodium content in joint sodium MR reconstructions using anatomical regularization and T2* estimation at 3T
Authors: Schramm Georg , Qian Yongxian , Nuyts Johan , Boada Fernando
Published: August 2023

Sodium MR signal acquisition and image reconstruction are severely hampered by the fast relaxation properties of the sodium nuclei. Signal decay due to fast transverse relaxation during readout leads to loss of high frequency information and severe partial volume effects (e.g.signal spill over from CSF into GM). In this work, we apply a reconstruction framework including anatomical regularization and signal decay modeling and estimation to dual echo sodium data to three subjects to investigate its effect on cortical grey matter sodium quantification.
Three-component IVIM fitting in cerebrovascular disease using physics-informed neural networks: repeatability and accuracy
Authors: Voorter Paulien H.M. , Backes Walter H. , Gurney-Champion Oliver J. , Wong Sau-May , Staals Julie , van Oostenbrugge Robert-Jan , van der Thiel Merel M. , Jansen Jacobus F.A. , Drenthen Gerhard S.
Published: August 2023

Next to parenchymal diffusion and microvascular pseudo-diffusion, a third diffusion component is present in cerebral intravoxel incoherent motion (IVIM) imaging, representing interstitial fluid. Fitting the three-component IVIM model using conventional fitting methods strongly suffers from image noise. Therefore, we explored the applicability of a physics-informed neural network (PI-NN) fitting approach, previously shown to be more robust to noise. Using test-retest data from sixteen patients with cerebrovascular disease, we found higher repeatability of all IVIM parameters using PI-NN. Furthermore, simulations showed that PI-NN provided more accurate IVIM parameters. Hence, using PI-NN is promising to obtain tissue markers of cerebrovascular disease.
Retinotopic connectivity in the cerebellum for different cognitive states
Authors: Zuiderbaan Wietske , van der Zwaag Wietske , Knapen Tomas
Published: August 2023

We used the retinotopic connective field model to investigate how retinotopic organization in the cerebellum depends on cognitive state. Previous work found three retinotopic clusters in the cerebellum. These regions were found using a standard bar mapping stimulus with fixation task. Here, we show that with a more naturalistic condition, we find an extra cluster to be retinotopically organized. Furthermore, we show that the oculomotor vermis shows a gradient in visual field eccentricity, that was not revealed using the simple stimulus. Our results underline the importance of using a naturalistic condition in studying the retinotopic organization of the cerebellum.
Evaluation of flow suppression methods for multi-echo gradient echo carotid wall imaging
Authors: Liu Junmin , Oran Omer , Drangova Maria
Published: August 2023

By adding long TEs to the Dixon acquisition, the chemical-shift-based T2*-weighted multi-echo GRE (CS-T2*-mGRE) techniques have gained attention, because they are able to generate co-registered multi-contrast images and quantitative maps. However, flow-suppressed CS-T2*-mGRE sequences have not been evaluated for carotid wall imaging. We compared the performance of simultaneous quantification of fat fraction (FF) and R2* from CS-T2*-mGRE sequences with and without saturation slabs, and with the incorporation of DANTE pulses for black blood imaging (DANTE-CS-T2*-mGRE); we used the FF for fat-suppression to better visualize the vessel wall from DANTE-CS-T2*-mGRE as well as the carotid artery lumen from CS-T2*-mGRE.
Accelerated Multiband Cine Cardiac Magnetic Resonance Imaging using Deep Learning
Authors: Chen Xiao , Zheng Yuan , Chen Eric , Zhang Zhongqi , Ding Yu , Xu Jian , Chen Terrence , Sun Shanhui
Published: August 2023

Cine CMR is a routinely performed technique for heart anatomy and function analysis. In clinics, repeated breathholdings are performed to acquire multiple 2D slices to cover the whole heart, which further exacerbates the discomfort and challenges for young and severe-diseased patients. In this study, we halved the breathholding time for cine CMR using MB technique. Multiple sampling patterns were designed and studied for the best reconstruction quality. A NN leveraging the Siamese structure was designed to reconstruct the accelerated MB data and achieved great image quality.