bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging the pulsatile fluid source distribution and pressure gradients in the brain using a poroelastic model and intrinsic pulsatile motions.
Authors: McGarry Matthew , Weaver John , Paulsen Keith
Published: August 2023

The pulsatile tissue motions from the cardiac cycle can be imaged using retrospectively gated phase contrast MRI. Modeling brain tissue as a poroelastic material allows a distribution of pulsatile fluid sources to be computed which reproduce the measured motions by estimating the RHS vector of a finite element representation of the poroelastic system. This Fluid source imaging (FSI) represents a completely new type of image parameterization that could offer unique diagnostic signatures. The associated pressure field gradients are also the driving force for interstitial fluid movement, where disruptions are thought to cause buildup of waste products which leads to dementia.
GraspCEST: Fast Free-Breathing 3D Steady-State CEST MRI Using Golden-Angle Radial Sparse MRI
Authors: Xu Xiang , Xia Ding , Block Kai , Feng Li
Published: August 2023

In this project, we proposed a fast 3D CEST MRI technique called GraspCEST, which is based on the combination of CEST-prepared stack-of-stars golden-angle radial sequence and multicoil compressed sensing reconstruction. Using this technique, we were able to perform lipid suppressed, free-breathing 3D CEST imaging of the liver. We have demonstrated that it is possible to accelerate imaging speed and achieve full Z-spectra acquisition of the liver within 5 min. The GraspCEST technique can be a useful tool in studying glycoNOE in the liver.
High-Resolution Compressed Sensing 19F-MRI Reveals Progression of Neuroinflammation in Autoimmune Encephalomyelitis
Authors: Starke Ludger , Delgado Paula , Millward Jason , Klix Sabrina , Niendorf Thoralf , Waiczies Sonia
Published: August 2023

Improving sensitivity has been the major challenge towards realizing the promises of 19F-MRI. Here we combine a cryogenic surface RF probe and compressed sensing to achieve high spatially resolved 19F-MRI of neuroinflammation in a challenging longitudinal study. Inflammation in the CNS was observed even in the absence of neurological symptoms and detailed signals along the CNS vasculature are clearly resolved. Together with effective longitudinal registration this allows an in-depth study of disease progression.
Cortical thickness at 3 years post-ischemic stroke: seeking vascular imaging signatures
Authors: Khlif Mohamed Salah , Werden Emilio , Bird Laura , Brumley-Egorova Natalia , Brodtmann Amy
Published: August 2023

Cortical thinning has been used both for diagnosis and disease monitoring. Few studies have examined longitudinal changes in cortical thickness following ischemic stroke. We compared cortical thinning, vortex-wise and region-wise, between ischemic stroke survivors and stroke-free control participants at 3 months and 3 years post-stroke using linear mixed-effect regression and correcting for age and sex. At 3 years, there was widespread cortical thinning in ischemic stroke, especially in the ipsilesional cortex, in lobes implicated in motor, sensory, and memory processing and recovery.
Heterogeneous diffusivity changes within human stroke lesions measured with oscillating gradient spin echo diffusion MRI
Authors: Zhou Mi , Stobbe Robert , Buck Brian , Butcher Ken , Fairall Paige , Boyd Annie , Emery Derek , Feiweier Thorsten , Beaulieu Christian
Published: August 2023

Short diffusion time oscillating gradient spin echo (OGSE) showed less water diffusion reduction in acute human stroke lesions (n=28) than the typical clinically used long diffusion time pulsed gradient spin echo (PGSE) method. The diffusion time dependency is far greater in ischemic lesions, particularly white matter, than in contralateral healthy brain. These effects were heterogeneous across the lesion with larger OGSE-PGSE differences in regions indicative of larger axons. The range of MD decrease in lesions across patients as measured with OGSE and PGSE showed a linear correlation and is consistent with concomitant axon beading and swelling implied from prior simulations.
High Spatiotemporal Resolution Breast MR Increases Cancer Detection and Reduces Unnecessary Biopsies in Patients with Marked BPE
Authors: Eskreis-Winkler Sarah , Dixon Linden , Jindal Ragni , Sung Janice , Feigin Kimberly , Sutton Elizabeth , Martinez Danny , Pinker Katja
Published: August 2023

Contrast-enhanced breast MRI is a powerful tool for breast cancer detection, but can be limited in the setting of marked background parenchymal enhancement (BPE), which can mask underlying lesions. We found that among patients with marked BPE, positive predictive value (PPV2) and cancer detection rate (CDR) were statistically significantly increased when the high spatial/high temporal resolution protocol, rather than the standard protocol, was used. The interval cancer rate was not significantly different between these groups.
The diagnostic performance of modified BI-RADS using high-resolution diffusion weighted images (HR-DWI), T1WI and T2WI
Authors: Ota Rie , Kataoka Masako , Iima Mami , Kishimoto Ayami , Honda Maya , Miyake Kanae , Yamada Yosuke , Takeuchi Yasuhide , Toi Masakazu , Nakamoto Yuji
Published: August 2023

This study aimed to evaluate the diagnostic performance of non-contrast protocol combining high-resolution diffusion weighted images (HR-DWI) with rs-EPI, T1WI and T2WI, using modified BI-RADS. In total, 98 breast lesions (60 malignant and 38 benign lesions) were categorized and compared to the pathological diagnosis. Area under the ROC curve (AUC)s of the non-contrast protocol were 0.90 (95% confidence interval (95%CI) : 0.82-0.95) for both readers. When excluding cases in which ADC value could not be measured, the AUC values were improved. Non-contrast protocol with modified BI-RADS can be used to evaluate breast lesions.
Mechanically Induced contrast in OA and control cartilage tissues at histological length scales probed by multi-scale 1H/23Na MRS and MRI at 9.4T.
Authors: Pavlovskaya Galina , Belek Onur , Meersmann Thomas , Philp Christopher , McLaren Jane , Walsh David , Scammell Brigitte
Published: August 2023

We reveal intriguing experimental results providing the evidence that triple quantum filtered sodium relaxation time associated with histologically confirmed sodium bound to glycosaminoglycans (GAGs) in the cartilage matrix could be a marker for earlier osteoarthritis. The change appears only when cartilage specimens are subjected to mechanical load corresponding to 200N force applied normal to the cartilage surface. Hence, this mechanically induced change can potentially serve as a health score of cartilage tissues in health and disease in vivo.
Renal fibrosis investigated by in vivo multifrequency MR elastography in a rat model of chronic kidney disease.
Authors: Garczyńska Karolina , Hahndorf Julia , Stolzenburg Nicola , Taupitz Matthias , Braun Jürgen , Sack Ingolf , Schnorr Jörg , Guo Jing
Published: August 2023

Using in vivo tomoelastography and multiparametric MRI (mp-MRI) we investigated kidneys of 10 rats with adenine-induced chronic kidney disease (CKD) and 8 healthy controls. In CKD rats, increased kidney volume, shear wave speed (SWS, related to stiffness) and wave penetration rate (related to inverse viscosity) were observed, while water diffusivity was reduced. These imaging findings were correlated with histopathologically quantified renal fibrosis. Our results suggested that collagen accumulation during CKD progression transforms soft-compliant renal tissue into a more rigid-solid state with reduced water mobility and shows that tomoelastography is a promising tool for non-invasive monitoring of disease progression.
In vivo demonstration of generalized anisotropy profiles for resolving boundaries between subcortical gray and white matter
Authors: Jones Robert , Maffei Chiara , Tian Qiyuan , Huang Susie , Sundaresan Vaanathi , Yendiki Anastasia
Published: August 2023

We investigate the use of generalized anisotropy profiles (GAPs) for delineating boundaries between subcortical gray and white matter in vivo. Replicating results from a previous ex vivo study, we show that GAPs, which are computed from the diffusion propagator, provide more informative contrasts than T1- and T2-weighted images or conventional diffusion metrics. An undersampled Cartesian-grid sampling of q-space can be used to obtain these profiles with a reasonable scan time. Thus, GAPs show promise as a multi-channel contrast that could be used in the future to improve structural segmentation.
Comparing population Receptive Field mapping using VASO-CBV and BOLD
Authors: Oliveira Icaro , Cai Yuxuan , Hofstetter Shir , Siero Jeroen , Zwaag Wietske , Dumoulin Serge
Published: August 2023

We extended the use of VASO-CBV to pRF mapping modeling. We show that VASO-CBV data can be used reliably to map polar angle and eccentricity, similar to BOLD-based data. In addition, the pRF size increased systematically from V1 to V3 similarly for BOLD and VASO-CBV estimates. The higher microvascular specificity of VASO-CBV did not result in smaller pRF size estimates. This result suggests that the vascular contribution to the pRF size is not dominant in either VASO-CBV or BOLD-based pRF mapping.
Additive manufacturing for the fabrication of subject-specific MRI passive shim and RF coil configurations
Authors: Vanduffel Hanne , Parra Cesar , Gsell Willy , de Oliveira Silva Rodrigo , Himmelreich Uwe , Vanduffel Wim , Sakellariou Dimitrios , Ameloot Rob
Published: August 2023

Additive manufacturing methods are cost and time efficient methods, in particular, for the fabrication of subject-specific MRI hardware components. A novel powder-binder jetting method was developed to deposit variable concentrations of magnetic ink at precise pre-calculated positions to sculpt B0 towards a target distribution via the passive response of the 3D printed shims. Discrete spherical harmonic terms were printed as a proof-of-concept towards the manufacturing of subject-specific passive shims. Stereolithography (SLA) and Laser Powder Bed Fusion (L-PBF) manufacturing methods were developed for the fabrication of subject-specific RF coils. Significant gains in image quality, scan time and subject comfort were observed.
On-coil digitization with a 130nm CMOS receiver: Electromagnetic compatibility and use for a wearable knee array
Authors: Port Andreas , Luechinger Roger , Burger Thomas , Pruessmann Klaas
Published: August 2023

The relevant electromagnetic compatibility mechanisms of an integrated receiver based on 130nm CMOS technology are investigated. Imaging performance is verified with a digital wearable array, which was based on liquid metal and layed out for knee imaging. The study found that gradient switching and transients related to detuning are not critical in terms of EMC. However, coupling of RF to the preamplifier input has been found to exceed the receiver’s acceptable input voltage of 1.7V despite the use of protection diodes. Thus, a B1 limitation was applied and robust imaging performance was demonstrated in phantom and in vivo imaging.
Exploiting a trade-off between preamplifier noise figure and bandwidth in the design of multi-nuclear MRI detectors
Authors: Simonsen Anders , Zhurbenko Vitaliy , Heredia Juan Diego Sanchez , Wang Wenjun , Ardenkjær-Larsen Jan Henrik
Published: August 2023

The perspective of extending bandwidth of an MRI detector to ~3.2MHz can enable imaging of 13C, 23Na and 129Xe nuclei with a single coil in 3T scanners. Currently, multinuclear imaging is done using bulky multi-coil setups or triple-tuned matching networks. In this work we propose a different approach to cover several nuclei frequencies by extending the bandwidth of a single receive coil manipulating impedance of the preamplifiers. A trade-off analysis of the achieved bandwidth and SNR is performed. A design example is presented. The approach promises compact and light-weight realization, which is particularly useful for ultra-flexible multinuclear receive arrays.
Simultaneous hemodynamic and structural imaging of ischemic stroke with MR Fingerprinting ASL
Authors: Fan Hongli , Su Pan , Lin Doris , Goldberg Emily , Walker Alexandra , Leigh Richard , Hillis Argye , Lu Hanzhang
Published: August 2023

Tissue perfusion and structural imaging provides important information in the evaluation of ischemic stroke. MR-fingerprinting (MRF) arterial spin labeling (ASL) is a novel noninvasive method of ASL perfusion that allows simultaneous estimation of cerebral blood flow (CBF), bolus arrival time (BAT), and tissue T1 map in a single scan of <4 minutes. Here we evaluated the utility of MRF-ASL in ischemic stroke patients in depicting hemodynamic and structural abnormalities, as well as predicting neurological deficits and disability.
A prospective patient study using pseudocontinuous Arterial Spin Labeling to detect pulmonary embolism: preliminary results of an ongoing study
Authors: Seith Ferdinand , Zhang Cecilia , Kolb Manuel , Gückel Brigitte , Pohmann Rolf , Martirosian Petros , Othman Ahmed
Published: August 2023

We present preliminary results of a prospective study of 96 patients examined with pCASL-MRI of the lung with suspected pulmonary embolism. pCASL-MRI of the lung was acquired in a 1.5T scanner by labeling the pulmonary trunk during systole. Coronal, sagittal and axial images were acquired using a fast bSSFP sequence. Additionally, a mulit-slice coronal bSSFP imaging the whole lung was performed. Two blinded readers evaluated MR-images to detect pulmonary embolism and noted the diagnostic confidence (5=very good). Compared to CT, sensitivity and specificity were 0.971 and 0.951. The median diagnostic confidence was 5 in both readers (kappa 0.739).
Free-running 3D anatomical and flow MRI using Synchronization of Neighboring Acquisitions by Physiological Signals (SyNAPS)
Authors: Falcão Mariana , Mackowiak Adèle , Rumac Simone , Bacher Mario , Rossi Giulia , Prša Milan , Tenisch Estelle , Rutz Tobias , Bastiaansen Jessica , Van Heeswijk Ruud , Speier Peter , Markl Michael , Stuber Matthias , Roy Christopher
Published: August 2023

We introduce a novel method for combining multiple free-running MRI acquisitions together, through the use of cardiac and respiratory signal extraction with Pilot Tone navigation called Synchronization of Neighboring Acquisitions by Physiological Signals (SyNAPS). We demonstrate the initial feasibility and utility of SyNAPS on a setup for joint reconstruction of back-to-back dynamic anatomical and flow MRI acquisitions, here named 4D flow SyNAPS. Overall, 4D flow SyNAPS enabled an improved structural visualization, when compared to the magnitude images from free-running 4D flow datasets alone, and the resulting flow measurements showed better agreement with reference 2D flow acquisitions.
Synthesis of 4D Flow Tensor MRI of Patient-Specific Turbulent Flow
Authors: Dirix Pietro , Buoso Stefano , Peper Eva , Kozerke Sebastian
Published: August 2023

We present a pipeline to synthesize patient-specific pulsatile turbulent 4D flow MRI datasets of the aorta. Aortic motion and inflow are extracted from in-vivo 2D cine and time-resolved 2D phase-contrast data. Computational fluid dynamics is used to obtain 4D velocity and turbulence fields to simulate MR signals using multipoint 4D flow tensor MRI protocols, which are reconstructed into velocity and turbulence maps with a Bayesian approach. As a result, realistic paired data of ground truth and their projection into MR images enable assessing accuracy and precision of encoding and inference, training of inference machines and, ultimately, deriving optimal experimental designs.
300 mT/m diffusion MRI 'below the neck': First results in healthy prostate
Authors: Molendowska Malwina , Palombo Marco , Fasano Fabrizio , Jones Derek , Alexander Daniel , Panagiotaki Eleftheria , Tax Chantal
Published: August 2023

This work showcases the first ever use of ultra-strong gradient in ’below the neck’ human MRI. It assesses the benefits, compared to more commonly-available gradient strengths, of 300mT/m gradients for comprehensive characterization of the prostate gland. Leveraging such gradient amplitudes enables unique tissue contrasts, with a potential to improve specificity and/or sensitivity of current MRI methods for prostate cancer characterisation and detection.
A novel 4D-MRI method enabling real-time image streaming for tumor tracking in radiotherapy
Authors: Keijnemans Katrinus , Borman Pim , Raaymakers Bas , Fast Martin
Published: August 2023

In MR-guided abdominothoracic radiotherapy, fast 2D imaging for MLC tracking and respiratory-correlated 4D imaging for dose accumulation is desirable. We developed a hybrid 2D/4D MRI method for pre-beam and beam-on imaging, which continuously acquires and reconstructs T2w coronal simultaneous multi-slice (SMS) images. Pre-beam 4D-MRIs were used to calculate a 3D mid-position reference image. Beam-on SMS data were used to extract real-time motion using a 4D-based motion model, and continuous 4D-MRIs. Dynamic updating of the 4D-motion model yielded the best real-time motion estimation. The presented hybrid 2D/4D MRI method can potentially facilitate novel MR-guided abdominothoracic radiotherapy workflows.
Integrated Multi-Task MR For Abdominal Adaptive Radiation Therapy
Authors: Chen Junzhou , Han Pei , Tian Ye , Yang Wensha , Li Debiao , Nayak Krishna , Yang Yingli , Christodoulou Anthony , Fan Zhaoyang
Published: August 2023

MR applications in radiation therapy has shown great promise for highly conformal treatment. However, MRgRT in the abdomen remains challenging due to motion and the sheer number of organs. In this work, we have demonstrated an integrated multi-task MR platform for adaptive radiation planning and treatment monitoring in the abdomen. In our proposed framework, from a single "pre-beam" scan we are able to generate a volumetric, multi-contrast and motion resolved images for adaptive treatment planning as well as enabling multi-contrast 3D real-time display during treatment. We demonstrate this capability in 3T and 0.55T.
Deep Subspace Learning for Improved T1 Mapping using Single-shot Inversion-Recovery Radial FLASH
Authors: Blumenthal Moritz , Wang Xiaoqing , Uecker Martin
Published: August 2023

Subspace based reconstructions can be used for quantitative imaging. We extend the recently added neural network framework in BART to support non-Cartesian trajectories and linear subspace constraint reconstructions. The network is trained to reconstruct coefficient maps from single-shot radial FLASH inversion recovery acquisitions. T1 maps are estimated using pixel-wise fitting to the signal model. The reconstruction quality of the coefficient and T1 maps are improved compared to an $$$\ell_1$$$-Wavelet regularized reconstruction. The subspace constraint network can be used for any linear subspace constraint reconstruction.
Integration of blip reversal with CAIPI sampling enables simultaneous correction of slice aliasing and distortion in 3D multi-slab diffusion MRI
Authors: Li Ziyu , Miller Karla , Wu Wenchuan
Published: August 2023

3D EPI can provide optimal SNR efficiency for high-resolution diffusion MRI but is prone to aliasing of edge slices and in-plane distortion artifacts. We propose a highly-efficient method for correcting slice-aliasing and distortion for 3D multi-slab imaging without increasing scan time. Blip reversal is integrated into CAIPI sampling within a single scan. In addition, we extend the FOV along the slice direction to remove slice-aliasing artifacts. Field maps are estimated from the blip-reversed data and incorporated in the final joint reconstruction. The efficacy of the method is quantitatively and systematically validated using highly realistic simulations.
A multi-echo low-rank and sparse algorithm that reduces the bias of global fluctuations on the estimation of neuronal signal
Authors: Uruñuela Eneko , Moia Stefano , Caballero-Gaudes César
Published: August 2023

This work introduces a novel multi-echo fMRI deconvolution approach that reduces the effect of global fluctuations (e.g., motion effects, physiological confounds, artefacts) on blindly mapping the brain’s response to single-trial BOLD events without prior timing information. The new sparse-plus-low-rank multi-echo multivariate paradigm free mapping (SPLORA) algorithm is compared with a trial-based known-timing GLM analysis and its predecessor multivariate multiecho paradigm free mapping (MvME-PFM) approach. This method allows exploring the brain’s functional dynamics during task, naturalistic and resting-state paradigms, being less affected by motion and physiological confounds, thus avoiding global signal regression to estimate neuronal related activity with multi-echo fMRI.
Mapping water exchange in the human brain using diffusion MRI with free waveform encoding
Authors: Chakwizira Arthur , Szczepankiewicz Filip , Westin Carl-Fredrik , Vis Geraline , Knutsson Linda , Sundgren Pia , Nilsson Markus
Published: August 2023

Temporal velocity correlations of diffusing particles carry information about the structure of the diffusion environment. Studying high-order velocity autocorrelation functions can aid in understanding how signal is influenced by restricted diffusion and exchange, and in turn how to design experiments that are sensitive/independent to these phenomena. In this work, we employ numerical simulations on a variety of substrates to demonstrate this notion. We find that the fourth order velocity autocorrelation bears a distinctive signature of exchanging systems. In addition, we highlight that the effect of exchange on the second order velocity autocorrelation is negligible when exchange is barrier-limited.
Isolating restriction and exchange in gray matter using double and single diffusion encodings with equal diffusion weighting
Authors: Cai Teddy , Williamson Nathan , Ravin Rea , Basser Peter
Published: August 2023

The diffusion MR signal in complex tissue such as gray matter exhibits non-Gaussian signal attenuation due to exchange and restrictions. Existing signal models typically ignore one or both effects by assuming Gaussian diffusion or negligible exchange. We propose a more rigorous signal model that incorporates both effects. Subsequently, an acquisition scheme utilizing equal double diffusion encodings ($$$b_1=b_2$$$) at various mixing times, and single diffusion encodings with the same total weighting $$$b=b_1+b_2$$$, is designed to independently characterize the effects of restriction and exchange. The method is tested on live and fixed gray matter specimen using a low-field, high-gradient MR system.
Revealing diffusion time-dependence and exchange effect in the in vivo human brain gray matter by using high gradient diffusion MRI
Authors: Lee Hong Hsi , Olesen Jonas , Tian Qiyuan , Llorden Gabriel Ramos , Jespersen Sune , Huang Susie
Published: August 2023

The characteristic signal time-dependence in the brain gray matter indicates a significant exchange effect, modeled by an extension of the Kärger exchange model. Here we perform in vivo diffusion measurements with varying time scales (21-40 ms) up to high b-values (≤22 ms/µm2) in a healthy subject on an HCP scanner, and observe the signal time-dependence in frontal lobe, temporal lobe, and limbic system. The estimated residence time is 2-7 ms in the brain gray matter, suggesting that diffusion in neurite and extra-cellular space is coarse-grained at clinical diffusion time scale.
High temporo-spatial resolution VASO reveals differential laminar reactivity to event-related stimuli at 7T
Authors: Dresbach Sebastian , Huber Renzo , Goebel Rainer
Published: August 2023

Due to its high specificity, VASO plays a major role in laminar fMRI. To mitigate its lower sensitivity compared to GE-BOLD researchers mostly employ block-designs to increase SNR. Here, we developed a VASO sequence with a short TR (895ms volume acquisition) and showed that it provides the means to capture layer-specific haemodynamic responses with high spatio-temporal resolution. During event-related stimulation, we show reliable responses in visual and somatosensory cortices. Furthermore, the short TR and high specificity of VASO enabled us to show differences in laminar reactivity and onset times, thus demonstrating the high value of event-related designs using CBV-based fMRI.
Normative modelling detects abnormal functional connectivity in schizophrenia
Authors: Saraiva Duarte , Ferreira Hugo
Published: August 2023

Machine learning (ML) applications on the diagnosis of neuropsychiatric disorders (NPD) have not reached clinical practice yet, as the continuous spectrum of NPD demands more complex, non-binary classification approaches. Herein, a ML-based normative model was created from healthy subjects, which “fails” when tested on schizophrenia patients. In particular, abnormal functional connectivity patterns were found in such patients, in agreement to what has been described in the literature. Moreover, a clustering method and analysis at the individual level indicate that subgroups may exist within the schizophrenia spectrum, suggesting that a personalized and precision-based diagnosis is within reach for such NPD.
Alterations in intrinsic functional networks in squirrel monkey brain produced by dorsal column lesion of spinal cord using resting state fMRI
Authors: Sengupta Anirban , Mishra Arabinda , Wang Feng , Chen Li Min , Gore John
Published: August 2023

The goal was to study how intrinsic functional networks within squirrel monkey brain undergo changes in connectivity after a dorsal column lesion (DCL) of the spinal cord. We used independent component analysis (ICA) to decompose whole brain fMRI data into spatially independent functional networks. Thirteen networks were identified, many of which resemble networks from human and macaque brain studies. Inter-network connectivity was computed before and after DCL of the cervical spinal cord. Changes in inter-network connectivity were not restricted to sensorimotor areas but spread over other cortical areas. Also, one of the connectivity increased significantly, possibly indicating compensation post lesion
3D MRI atlases of congenital aortic arch anomalies and normal fetal heart: application to automated multi-label segmentation
Authors: Uus Alena , van Poppel Milou , Steinweg Johannes , Grigorescu Irina , Collado Alexia Egloff , Gilliland Paula Ramirez , Roberts Thomas , Hajnal Joseph , Rutherford Mary , Lloyd David , Pushparajah Kuberan , Deprez Maria
Published: August 2023

This work introduces the first black blood 3D T2w MRI atlases of the normal fetal heart and congenital aortic arch anomalies. The atlases were generated from 87 subjects from normal, CoA, RAA and DAA cohorts and also include multi-label segmentations of the major cardiovascular structures. We further evaluated the feasibility of using deep learning for automated multi-label vessel segmentation in 3D T2w motion-corrected MRI images of the fetal heart.
Medullary vein architecture modulates the white matter BOLD CVR response to CO2: observations from high-resolution T2* weighted imaging at 7T
Authors: Bhogal Alex
Published: August 2023

Brain stress testing using blood oxygenation level-dependent (BOLD) MRI to evaluate changes in cerebrovascular reactivity (CVR) is of growing interest for evaluating white matter integrity. However, even under healthy conditions, the white matter BOLD-CVR response differs notably from that observed in the gray matter. The confluence of arterial hemodynamics and BOLD signal characteristics weighted by venous architecture unrelated to smooth-muscle mediated dilation/contraction play a significant role in defining the WM BOLD-signal response to hypercapnia. This caveat should be taken into account when attributing disease mechanisms and/or progression to presumed impaired WM BOLD-CVR.
MRS-Detectable Metabolic Biomarkers of TERT positive Glioblastoma
Authors: Minami Noriaki , Hong Donghyun , Stevers Nicholas , Barger Carter , Batsios Georgios , Gillespie Anne Marie , Costello Joseph , Viswanath Pavithra , Ronen Sabrina
Published: August 2023

Telomerase reverse transcriptase (TERT) expression results from TERT promoter mutations and is a hallmark of cancer. GABPB1, its upstream transcriptional factor, was recently identified as a promising tumor-specific therapeutic target. However, imaging methods that can detect TERT expression and its inhibition with emerging GABPB1-based therapeutics are limited. Here, we demonstrate that the combination of 1H-MRS and hyperpolarized 13C-MRS of [1-13C]pyruvate allow detection of TERT modulation in TERT-expressing GBM cells and in vivo tumors. These findings could be translated to the clinic and thus improve the monitoring and personalized treatment of GBM.
Differentiation of hepatocellular carcinoma from intrahepatic cholangiocarcinoma by mDIXON Quant and intravoxel incoherent motion imaging
Authors: Lin Tao , Wang Jiazheng , Lin Liangjie , Chen Lihua , Song Qingwei , Pu Renwang , Zhao Ying , Ren Xue , Xu Qihao , Liu Ailian
Published: August 2023

Differentiation between hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC), the most common types of primary liver cancer, is important for the treatment planning and prognosis, but remains challenging via conventional radiological tools. Results by this study indicated that both mDIXON Quant and IVIM parameters showed significant different between HCC and ICC groups, and their combination can be of great potential value for clinical differential diagnosis between the two lesions.
Assessment of resolution and noise in MR images reconstructed by data driven approaches
Authors: Lauer Katja , Kleineisel Jonas , Borzì Alfio , Bley Thorsten , Köstler Herbert , Wech Tobias
Published: August 2023

Data-driven reconstruction of undersampled raw data has gained more and more importance in recent years. Due to the non-linear and non-stationary transform characteristics of these imaging methods, objective image quality assessment is difficult. We propose a heuristic approach based on local point spread functions and multiple replica reconstructions, to enable the derivation of resolution- and g-factor-maps for individual images. The method is exemplarily applied in T1- and T2-weighted images of the brain, using a UNet and a Variational Network trained with data from the fastMRI project.
Mitigating synthetic T2-FLAIR artifacts in 2D MAGiC using keyhole and deep learning based image reconstruction
Authors: Chatterjee Sudhanya , Takei Naoyuki , Patil Rohan , Gho Sugmin , Banerjee Suchandrima , Wiesinger Florian , Shanbhag Dattesh
Published: August 2023

Magnetic resonance image compilation (MAGiC) is a single click scan that provides multiple contrast-weighted images in around 5 mins. This makes it an effective diagnostic option in clinical settings. However, synthetic T2-FLAIR is known to have partial volume artifacts which impacts its diagnostic performance. In this work, we propose a method to mitigate partial-volume artifacts in synthetic T2-FLAIR using a separately acquired fast T2-FLAIR contrast information combined with keyhole and deep learning-based image reconstruction.
Robust diffusion-weighted spectroscopic imaging throughout the mouse brain
Authors: MOUGEL Eloïse , Valette Julien
Published: August 2023

Being more specific to cellular microstructure than water diffusion, diffusion-weighted spectroscopic imaging (DW-MRSI) is a powerful tool for measuring disorders in cortical gray matter. Nevertheless, measurement in the cortex is difficult due to its proximity to the skull. We propose a selective DW-MRSI sequence, which avoids lipid contamination and measures the signal of metabolites even in the cortex. We performed an in vivo acquisition with this sequence and were able to measure an apparent diffusion coefficient over an entire brain slab.
Field-Cycling imaging identifies ischaemic stroke at magnetic field strength below 200 mT
Authors: Mallikourti Vasiliki , Ross James , Maier Oliver , Bödenler Markus , Stollberger Rudolf , Broche Lionel , MacLeod Mary-Joan
Published: August 2023

Field-Cycling imaging (FCI) is a new imaging technique able to image over a range of low magnetic field levels by rapid switching, to explore the variations in T1 relaxation time as a function of the magnetic field strength, known as T1 dispersion. Here we measured the T1 dispersion contrast from patients with ischaemic stroke. The infarct region in T1 maps corresponded to clinical images. T1 dispersions had different profiles between stroke areas and healthy brain areas, showing that ischaemic strokes can be imaged below 200 mT without contrast agents.
An Adaptive Target Field Framework for Complete Low Field MRI System Design
Authors: de Vos Bart , Remis Rob , Webb Andrew
Published: August 2023

In this work a low field point-of-care system design framework is created using target field methods for all of the hardware components. A new target field method for Halbach-based magnet optimization with variable ring diameter and spacing is derived. Magnet, gradient and RF are combined into a single framework which includes a feedback loop for dealing with the component interdependencies. The result is a pipeline which with a few user inputs can create an optimal magnet, gradient and RF design in minutes.
2D Imaging without Gradient Coils in a Low-Field Spokes-and-Hub Permanent Magnet
Authors: Kuang Irene , Stockmann Jason , Adalsteinsson Elfar , White Jacob
Published: August 2023

We demonstrate feasibility of 2D imaging without gradient coils in a spokes-and-hub permanent magnet for a low-cost hand-held educational MR scanner. With the ease of physically assembling the imaging system in mind, the magnet was designed asymmetrically, to introduce a built-in z-gradient, and with an axis of rotation for the top magnet, so it can be tilted by either linear or rotational actuators, and generate negative or positive x-gradients. Results from simulation, Hall-effect sensor measurements, and spin echo data show that the permanent-z plus x-gradient can be used to generate orthogonal fields, and disambiguate signals from a two-tube phantom.
Real-Time Water Fat Imaging at 0.55T with Spiral Out-In-Out-In Sampling
Authors: Tian Ye , Lim Yongwan , Nayak Krishna
Published: August 2023

Real-time MRI is a powerful tool to study organ function in a dynamic environment. Many of these regions of interest have both water and fat present, such as the heart and joints. Water/fat separation usually requires multi-echo sequences that utilize chemical shift to distinguish water and fat signals. At 0.55T, the chemical shifts are smaller, making it possible to use long readouts (e.g. spirals) to more efficiently acquire images. Here, we demonstrate spiral out-in-out-in bSSFP imaging combined with region-growing field map estimation for water/fat separation. We demonstrate high quality water/fat separated real-time movies of cardiac function and wrist motion.
High spatial resolution real-time imaging of respiratory effects on cerebrospinal fluid flow at 7T
Authors: Töger Johannes , Andersen Mads , Haglund Olle , Kylkilahti Tekla , Lundgaard Iben , Bloch Karin Markenroth
Published: August 2023

Methods to quantify CSF flow dynamics are important to study the physiology of intracranial pressure variations. Respiration influences the CSF flow, making real-time acquisitions necessary. This work investigates a high-resolution radial real-time flow sequence with golden angle acquisition and compressed sensing reconstruction at 7T for flow quantification of the CSF flow in the aqueduct. Phantom data shows that the proposed method accurately quantifies the slower aqueduct CSF flow oscillations caused by respiration, but underestimates faster cardiac oscillations. In vivo data shows good repeatability and an association between respiratory condition and net CSF flow.
Age dependent cerebrospinal fluid-tissue water exchange detected by non-invasive magnetization transfer indirect spin labeling MRI
Authors: Li Anna , Lin Chen , Liu Hongshuai , Li Yuguo , Duan Wenzhen , Xu Jiadi
Published: August 2023

Our understanding of the CSF exchange with surrounding tissues and its correlation with brain function is limited. We presented a non-invasive magnetization transfer indirect spin labeling (MISL) MRI method to quantify the water exchange between cerebrospinal fluid (CSF) and surrounding tissues in the brain by making use of the significantly different protein concentrations between CSF and other tissues. Water in the surrounding tissue is directly labeled by magnetization transfer from the abundant macromolecule pool. The reduction in the CSF signal corresponds to the water traveled to CSF, which is strongly age-dependent and weakly AQP4-dependent.
Non-contrast-enhanced free-breathing thoracic MRA using gated REACT at 3T in small children with congenital heart disease
Authors: Isaak Alexander , Mesropyan Narine , Hart Christopher , Kravchenko Dmitrij , Endler Christoph , Bischoff Leon , Zhang Shuo , Katemann Christoph , Weber Oliver , Kuetting Daniel , Attenberger Ulrike , Dabir Darius , Luetkens Julian
Published: August 2023

Application of high-resolution 3D MR angiography (MRA) in small children with congenital heart disease (CHD) is challenging and generally requires contrast agent administration. In a cohort of pediatric CHD patients (median age: 4 years), non-contrast-enhanced free-breathing gated 3D mDixon REACT-MRA provided comparable overall image quality to contrast-enhanced free-breathing 3D mDixon steady-state MRA for assessment of the thoracic vasculature. REACT-MRA allowed for accurate and reliable vessel size measurements. Although fat-water separation artifacts were observed, they could be extenuated by reconstruction of in- and out-of-phase images. Gated REACT-MRA allows for a contrast-free assessment of the thoracic vasculature in small children with CHD.
Feasibility of simultaneous non-contrast coronary MR angiography and vulnerable plaque imaging in acute myocardial infarction
Authors: Hajhosseiny Reza , Hartley Adam , Cole Graham , Munoz Camila , Sethi Amarjit , Al-Lamee Rasha , Gopalan Deepa , Ariff Ben , Kaprielian Raffi , Kunze Karl , Neji Radhouene , Prieto Claudia , Khamis Ramzi , Botnar René
Published: August 2023

CMR plaque imaging has the potential to predict future coronary events, but is limited by low spatial-resolution, misregistration artefacts, respiratory motion related image quality degradation and unpredictable acquisition times. Here we clinically evaluate the feasibility of a novel 3D free-breathing, non-rigid motion corrected, non-contrast CMR sequence (iT2prep-BOOST) that enables simultaneous, high-resolution visualisation of the coronary arteries and high-risk plaque features on co-registered bright and black blood images in patients presenting with acute myocardial infarction. We found that iT2prep-BOOST can simultaneously visualise coronary artery stenosis as well as culprit and bystander coronary plaque, as validated against invasive coronary angiography and OCT.
Free-running contrast-enhanced ultra-short TE (UTE) for cardiac and respiratory motion-resolved flow artifact-free 5D whole-heart MRI
Authors: Rossi Giulia , Romanin Ludovica , Falcão Mariana , Milani Bastien , Piccini Davide , Yerly Jérôme , Schwitter Jürg , Prša Milan , Rutz Tobias , Tenisch Estelle , Stuber Matthias , Roy Christopher
Published: August 2023

Free-running whole-heart MRI can suffer from flow artifacts. Despite the efficiency of 3D radial UTE in minimizing the latter, its integration as a free-running sequence has so far been challenging due to poor-quality self-gating, which has necessitated an inefficient dual-echo approach. In this work we show that self-gating signals from a single-echo ferumoxytol-enhanced free-running 3D radial UTE sequence are comparable to the dual-echo approach, allowing to significantly improve scanning efficiency and produce dynamic images that are free from flow artifacts.
Dual-module velocity-selective arterial spin labeling (dm-VSASL) using velocity-selective saturation and inversion pulses
Authors: Guo Jia
Published: August 2023

Recently velocity-selective saturation (VSS) based dual-module (dm-) preparation and velocity-selective inversion (VSI) based preparation have demonstrated improved SNR efficiency in velocity-selective arterial spin labeling (VSASL) than conventional single-module VSS based preparation. In this study, a novel strategy was developed to allow dm-VSI labeling to further improve the SNR efficiency. Implementation of dm-VSASL were evaluated for VSS and/or VSI combinations. The theoretical performance was compared via ASL signal modeling, and then validated by in vivo human experiments with an increase of 6.6%. Dm-VSASL is capable of providing further improved SNR performance, with potentially better suppression of diffusion attenuation/eddy current artifacts.
Learning Time-Adaptive Data-Driven Sampling Pattern for Accelerated 3D Myocardial Perfusion Imaging
Authors: Vishnevskiy Valery , Hoh Tobias , Kozerke Sebastian
Published: August 2023

We investigated potential benefits of optimizing accelerated 3D myocardial perfusion MRI by time-adaptive data-driven k-t Cartesian sampling during the scan. To this end, the sampling mask for each following acquisition window is inferred by a neural network on the fly using the acquired history of MR signal projections. It is demonstrated that time-adaptive data-driven sampling reduces reconstruction errors by 25% along with a reduction of signal underestimation during the contrast bolus passage when compared to a predefined fixed sampling pattern.
Deformation-field magnetic resonance imaging for non-invasive evaluation of disc deformation in vivo
Authors: Johansson Frida , Sirat Zainab , Hebelka Hanna , Brisby Helena , Nordström Fredrik , Lagerstrand Kerstin
Published: August 2023

In vivo evaluation of the intervertebral disc (IVD) during spinal loading may yield greater insight into the biomechanical properties of the IVD. This study aimed to investigate how the lumbar IVD deforms during loading, quantified with a novel non-invasive method utilizing MRI and image registration. Findings showed that the intradiscal deformation depends not only on disc degeneration but also on the lumbar spine level. This highlights the need for tools that can evaluate the mechanical properties of the disc in vivo. The proposed method offers a possibility to depict and track biomechanical changes non-invasively while characterizing disc structures in detail.
Silent Motion-Corrected ZTE for Quantitative T1 and T2 mapping
Authors: Ljungberg Emil , Wood Tobias , Solana Ana Beatriz , Barker Gareth , Wiesinger Florian
Published: August 2023

We present a method for retrospective motion-correction of silent ZTE for quantitative T1 and T2 mapping using self-navigation. A spiral phyllotaxis k-space trajectory was used to reconstruct motion navigators, which then were co-registered to obtain motion parameters. The method is demonstrated for neuroimaging, showing improved image quality of quantitative T1 and T2 maps after motion correction. These results further showcase the capacity of ZTE for robust, silent neuroimaging.
Measuring Diffusion of Healthy Human Muscle During Continuous Exercise from Motion-Compensated Intravoxel Incoherent Motion (IVIM) MRI
Authors: Foster Anna , Coll-Font Jaume , Perlman Or , Chen Shi , Eder Robert , Farrar Christian , Nguyen Christopher
Published: August 2023

To date, it is unclear if diffusion increases in skeletal muscles during exercise. We measured diffusion, perfusion, perfusion fraction, and capillary blood flow in the calf during continuous exercise from IVIM fits on both standard (M0) and second order motion-compensated (M2) DWI sequences combined with motion artifact rejection. As diffusion estimates from M2 proved unchanged by artifact rejection at various thresholds, it was used in choosing an outlier threshold. Without artifact rejection, M0 reported diffusion increases. Once artifacts were removed from M0 using this threshold, it measured similar diffusion values to M2 and neither sequence showed diffusion increases during exercise.
NeuroMix - A motion robust single scan brain exam
Authors: Sprenger Tim , van Niekerk Adam , Berglund Johan , Rydén Henric , Aventi Enrico , Skare Stefan
Published: August 2023

We have presented a new multi-contrast sequence, NeuroMix, which acquires T1w, T2w, T2-FLAIR, T2*w, and DWI contrasts in a single scan, requiring only one prescription and one prescan. NeuroMix includes single-shot EPI and FSE readouts as well as optional multi-shot FSE and 3DEPI acquisitions. The motion robustness of NeuroMix’s single-shot contrasts was generally good even when NeuroMix’s multi-shot sequences were unusable due to motion corruption resulting in a high probability to obtain diagnostic images. In conclusion, NeuroMix enables a fast and motion robust single-scan brain exam allowing higher patient throughput with less discomfort and possibly less need for sedation.
Shuttered Echo Planar fMRI with Dynamic Motion and Phase Correction
Authors: Sengupta Saikat , Polimeni Jonathan , Setsompop Kawin , Grissom William
Published: August 2023

Achieving submillimeter-resolution BOLD fMRI is a challenge since single-shot EPI suffers from long echo times, blurring, and image distortions, while multishot EPI suffers from motion- and respiration-induced shot-to-shot phase errors. In shuttered multishot EPI, data are acquired in each shot after exciting a set of interleaved “shutters” across the imaged slice. This enables high quality reconstructions from each shot, which in turn enables navigator-free shot-wise phase and motion corrections prior to reconstructing a full-FOV image. Herein we describe a full motion- and phase-correcting image reconstruction for dynamic shuttered EPI and validate it in head motion and BOLD fMRI experiments.
Advances in short-wave motion tracking: Jaw-mount markers and prospective motion correction
Authors: Schildknecht Christoph , Brunner David , Schmid Thomas , Prüssmann Klaas
Published: August 2023

Prospective motion correction has demonstrated significant value for human brain MRI. One issue that all marker-based motion trackers share is the marker fixation to the human head. Short-wave motion tracking can solve this issue since the small wireless marker can directly be attached to the upper jaw with the mouth completely closed. In this work, we present PMC in-vivo imaging with such a sensor. The high temporal and spatial resolution can be observed in the measured physiological motion trajectories, illustrating the high-quality motion of this sensor.
High resolution diffusion-weighted MRI combining markerless prospective motion correction and locally low-rank constrained reconstruction
Authors: Dai Ke , Chen Hao , Zhong Sijie , Bai Haoran , Zheng Jiaxu , Zhang Xinyue , Yang Shasha , Cao Tuoyu , Frydman Lucio , Wang Chaohong , Zhang Zhiyong
Published: August 2023

High-resolution diffusion-weighted MRI is susceptible to head movement artifacts and background phase variations. We investigate a crucial combination of prospective motion correction and Spatial-angular local low rank (SPA-LLR) constrained reconstruction to obtain robust multi-shot high-resolution diffusion-weighted MRI under substantial motion. Prospective motion correction with optical markerless motion tracking is used to remove artifacts and blurring due to bulk motion whereas locally low-rank regularization is used to correct remaining artifacts due to the background phase variations from scan to scan. We present the results in healthy adult volunteers, demonstrating high-resolution diffusion-weighted images and FA images under different motion patterns with PMC.