bluuebunny/crossref_metadata_2025 huggingface dataset:
Voxelwise estimation of multiple response functions and fiber orientation distribution functions in diffusion MRI
Authors: St-Jean Samuel , Leemans Alexander , Szczepankiewicz Filip , Beaulieu Christian , Nilsson Markus
Published: August 2023

We present a framework to compute a response function for each voxel using a fingerprinting approach and a per voxel, per compartment estimation of the fiber orientation distribution (FOD) function for diffusion MRI. The method first matches the powder-averaged signal to a database of candidate signals and estimates a unique FOD from this matched signal for each compartment. This is done by turning the candidate signals into continuous Legendre polynomials, leading to a set of linear equations to estimate coefficients of the FODs, without requiring a prior segmentation or averaging multiple response functions.
A novel clinical prostate diffusion MRI approach for combined measurement of ADC and non-monoexponential diffusion
Authors: Kuczera Stefan , Langkilde Fredrik , Maier Stephan E.
Published: August 2023

A novel clinical protocol for prostate diffusion imaging is presented. The commonly applied strategy of averaging MR signal at a small number of b-values is replaced by the acquisition of a whole range of b-values in conjunction with a model fitting post precessing step. With no increase in acquisition time, our results show that the same image quality can be achieved. As a main benefit, modelling is made more consistent and largely b-value independent for both the simple ADC model, as well as for more complex signal representations such as the kurtosis model.
Exploring Hybrid CNN-Transformer for Schizophrenia Classification using Structural MRI
Authors: Rao Vishwanatha , Zhang Junhao , Guo Jia
Published: August 2023

Schizophrenia diagnosis is clinically difficult due to the lack of biomarkers associated with the disease. While machine learning algorithms and convolutional neural networks (CNNs) have found success using neuroimaging inputs to diagnose the disease, they have historically not performed or generalized well enough for clinical use. We propose 3D-MIC-Transformer, the first transformer-based deep learning architecture applied to neurological disease classification that demonstrates state-of-the-art schizophrenia classification performance and generalization using structural MRI inputs. 3D-MIC-Transformer outperforms prior CNN implementations (AUROC: 0.985, accuracy: 0.933), and we believe 3D-MIC-Transformer can serve as a backbone for other disease classification tasks in the future.
Differentiation of NF2 Loss and S100 Positivity in Meningioma Using Dynamic Susceptibility Contrast MRI with Machine Learning at 3T
Authors: Buz-Yalug Buse , Danyeli Ayca Ersen , Tan Kubra , Can Ozge , Pamir Necmettin , Dincer Alp , Ozduman Koray , Ozturk-Isik Esin
Published: August 2023

Meningiomas are the most frequent primary intracranial and spinal tumors. In this work, we studied the relative cerebral blood volume (rCBV) changes in the meningiomas with NF2 loss and S100 positivity. Meningiomas with NF2-L had lower rCBV than NF2-NL, and S100 positive group had also lower rCBV than S100 negative group. The highest classification accuracies obtained using machine learning applications were 75.6% for NF2 molecular subsets and 75.2% for S100 molecular subsets.
Negligible loss in double tuning when stacking 1H to 31P dipoles in an 8-channel dipole array with 24 receivers at 7T
Authors: Karkouri* Jabrane , Forner* Ria , Lunenburg Martijn , Meliadò Ettore , Arteaga Catalina , Raaijmakers Alexander , Rodgers† Christopher , Klomp† Dennis
Published: August 2023

We present a novel dual dipole coil concept for 7T 31P metabolic imaging in the body.

We constructed an array of 8x stacked 1H/ 31P dipoles, evaluating their performance by bench measurements, EM modelling, phantom experiments and in vivo scans in human liver. Parameters such as coupling, transmission efficiency and SAR are compared to those of a whole-body 31P birdcage coil.
An 8-channel transmit 64-channel receive compact head coil for Next Gen 7T scanner with head gradient insert
Authors: Gunamony Shajan , Feinberg David
Published: August 2023

The NextGen 7T scanner is equipped with a high-performance head gradient insert and hence the radial space available on the patient table for radiofrequency (RF) coils is limited. In addition to a large visual field to support fMRI studies, a split-top receive array on a sliding mechanism is desirable for improved patient comfort. We have developed a novel 8-channel transmit 64-channel receive 7T head coil and implemented a sliding mechanism to operate within the limited space in the head gradient insert. In this abstract, we present the overall coil design, transmit array performance and preliminary phantom results.
Assessing Drug Effect on the Velocity Pulsatility in the Perforating Arteries of the Basal Ganglia at 3T-MRI in Pseudoxanthoma Elasticum
Authors: Pham Stanley , van Tuijl Rick , Bartstra Jonas , van den Beukel Tim , Biessels Geert Jan , de Jong Pim , Spiering Wilko , Velthuis Birgitta , Zwanenburg Jaco
Published: August 2023

This feasibility study aimed to detect drug effects on perforating artery velocity as measured with two-dimensional phase-contrast (2D-PC) velocity measurements at 3T-MRI. Seventeen patients with pseudoxanthoma elasticum were included into a treatment group who received etidronate (n=9) and into a placebo group (n=8). No significant differences were found between both groups at baseline and one-year follow-up. In the etidronate group, mean velocity (Vmean) was significantly higher at follow-up (5.61 [4.77–6.45] cm/s) compared to baseline (4.80 [4.05–5.54] cm/s). In the placebo group, Vmean did not increase significantly. Measuring drug effects was feasible using 2D-PC measurements at 3T-MRI.
Relative cerebral blood volume reduction in hyperintense brain regions of glioma patients treated with proton radio(chemo)therapy
Authors: Witzmann Katharina , Raschke Felix , Wesemann Tim , Appold Steffen , Krause Mechthild , Linn Jennifer , Troost Esther
Published: August 2023

Imaging biomarkers capable of distinguishing between tumor recurrence and treatment effect are of high relevance for radiation therapy. In 14 glioma patients, we analyzed changes in relative cerebral blood volume (rCBV) in areas of hyperintensities on T2-weighted magnetic resonance imaging (MRI) appearing after irradiation with protons. rCBV values were evaluated comparing the baseline and the latest follow-up measurement both visually and based on histograms. A significant rCBV perfusion decrease was observed in those hyperintensities, which may be interpreted as treatment effect. Further work is needed correlating the rCBV changes with histology and patient outcome.
Oxygen Extraction Fraction and Cerebral Metabolic Rate of Oxygen derived from DSC-MRI in Patients with Moyamoya Disease
Authors: Fahlström Markus , Lewén Anders , Enblad Per , Wikström Johan
Published: August 2023

Moyamoya disease is a cerebrovascular disease where changes to oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) are important parameters to assess the risk of future ischemic stroke. By applying a microvasculature model to dynamic susceptibility contrast (DSC) perfusion data parametric maps of both OEF and CMRO2 can be generated. For both OEF and CMRO2 significant differences between affected and unaffected vascular territorial regions were found. OEF and CMRO2 derived from DSC perfusion shows promise in detecting cerebral hemodynamic impairment in patients with moyamoya disease. However, further investigations are needed to clarify the clinical potential.
Oxygen-enhanced MRI of the lung at 3 tesla: R2* contrast in smokers and non-smokers
Authors: Kim Mina , Naish Josephine , Tibiletti Marta , Needleman Sarah , Szmul Adam , Higgins David , O’Connor James , Parker Geoff
Published: August 2023

T1-weighted dynamic lung OE-MRI is challenging at 3 T using gradient echo acquisitions due to decreased T1 relaxivity of oxygen and substantial ∆R2* contribution. We implemented a dual echo T1-FFE-based method at 3 T and evaluated signal enhancement behaviour and ∆R2*. The proposed method is shown to produce negative contrast on oxygen enhancement signal due to dominance of ∆R2* at TE larger than 0.4 ms. We also demonstrated that the contrast property of the percentage signal enhancement (PSE) is TE dependent. Longer TE enables differentiation on PSE values between non-smokers and smokers.
Examining lung microstructure using 19F MR diffusion imaging in COPD patients
Authors: Obert Arnd , Gutberlet Marcel , Kern Agilo , Kaireit Till , Glandorf Julian , Alsady Tawfik Moher , Wacker Frank , Hohlfeld Jens , Vogel-Claussen Jens
Published: August 2023

Diffusion of fluorinated gas in the short-time regime was measured using multiple gradient echo sequences with a single pair of trapezoidal gradient pulses. Pulmonary alveolar surface-to-volume ratio (S/V) was calculated using a first-order approximation of the time-dependent diffusion in a study with 20 healthy volunteers and 22 patients with chronic obstructive pulmonary disease (COPD). Median surface-to-volume ratio is significantly decreased in COPD patients compared to healthy volunteers (P<.0001). No significant difference was found between measurements within 7 days. Linear correlations were found with S/V from hyperpolarized 129Xe MRI (r=0.85, P=.001) and the forced expiratory volume in one second (r=0.68, P<.0001).
Changes in ACL T2* metrics from pre- to post-ovulatory phases of the menstrual cycle: A new biomarker for ACL-injury risk in females?
Authors: Argentieri Erin , Breighner Ryan , Koff Matthew , Potter Hollis
Published: August 2023

ACL T2* metrics were evaluated over the course of the menstrual cycle. During the pre-ovulatory phase, normally ovulating case subjects exhibited significantly shortened mean and median T2*S metrics compared to the post-ovulatory phase. Anovulatory control subjects displayed no significant changes in any ACL T2* metrics over time. Findings suggest that an increase in collagen bound water (T2*S) is present within the ACL during the pre-ovulatory phase, when both ACL-injury risk and anterior knee laxity are also increased.
Longitudinal comparison of medial and lateral meniscal T2* values within elite basketball players and swimmers
Authors: Argentieri Erin , Gold Garry , Majumdar Sharmila , Potter Hollis , Koff Matthew
Published: August 2023

Basketball players represent a population with an inherently high risk of sustaining meniscal injuries. Evaluation of quantitative MRI (qMRI) metrics of the meniscus within these athletes may improve clinical insight. To date, no studies have longitudinally evaluated meniscal T2* values in high performance athletes. Therefore, the purpose of this study was to utilize ultra-short TE (UTE) MRI to longitudinally evaluate medial and lateral meniscal T2* values within elite weight-bearing (basketball) and non-weight bearing (swimmers) athletes. Significant differences of T2* values were found between the medial and lateral menisci. No significant difference of meniscal T2* values were found between basketball players and swimmers.
T1 and T2* mapping of sheep forelimb aponeuroses with high-resolution ultra-short echo time (UTE) imaging
Authors: Maggioni Marta , Krämer Martin , Stark Heiko , Reichenbach Jürgen
Published: August 2023

Aponeuroses play a crucial role in the transmission of mechanical load in the muscle-tendon unit. Their contribution is, however, still under debate and they are difficult to image with MRI due to their short T2* decay. In this work, we use high-resolution 3D ultra-short echo time imaging with 50 echoes to investigate the T2* decay of the aponeurosis and build a three-component model to quantify the T2* values. Additionally, we quantified T1 using variable flip angle imaging. To our knowledge, this work is the first to report T1 and T2* values of the aponeurosis.
Comparison of Two Methods for Measuring Knee Cartilage Thickness in Lower Extremities Using 7T Magnetic Resonance Imaging: A Cadaver Study
Authors: Vilimek Dominik , Hager Benedikt , Schreiner Markus , Hanzlikova Pavla , Kahankova Radana , Janacova Veronika , Laurent Didier , Fuchssteiner Christoph , Weninger Wolfgang , Windhager Reinhard , Szomolanyi Pavol , Trattnig Siegfried , Juras Vladimir
Published: August 2023

Knee articular cartilage thickness may potentially serve as a marker for monitoring of the knee cartilage status. However, it is challenging to measure and quantify the articular cartilage thickness using in vivo MRI. In the present study, we evaluated 6 unpaired lower extremies of body donors using both a prototype segmentation software and a semi-automatic approach. Our results showed a low correlation (r = 0.45) between the two methods, indicating the challenge of determining cartilage thickness from MR images.
Correlation of Fractional Anisotropy and Histological Measures of Muscle Architecture in Vastus Lateralus in Legs with Injured ACL
Authors: Hardy Peter , Fry Christopher , Andersen Anders , Thompson Katherine , Feiweier Thorsten , Noehren Brian
Published: August 2023

We measured diffusion tensor properties of the vastus lateralus muscle in 30 subjects who had a torn ACL. DTI was acquired with a stimulated echo acquisition with a diffusion time of 185 ms. From biopsies of the muscle taken simultaneously we developed histological measures of muscle fiber cross sectional area and minimum Feret diameter. Linear regression analysis demonstrated strong association of the fractional anisotropy and minimum Feret diameter.
Two-dimensional population receptive field mapping of human primary somatosensory cortex
Authors: Asghar Michael , Panchuelo Rosa Sanchez , Schluppeck Denis , Francis Susan
Published: August 2023

High-resolution fMRI data of somatosensory cortex were obtained at 7T (n=7 participants) using a 4x4 grid of piezoelectric stimulators. Population receptive field (pRF) mapping was performed using different model specifications (1D Gaussian within-digit, 1D Gaussian between-digit, 2D Gaussian of within-digit and between-digit, Unconstrained model) and pRF sizes were estimated. Grouping pRF response by 4 preferred locations within digits (along tip-base axis) or by Brodmann areas revealed more elliptical pRFs within digit representations of D2 to D4 and more circularly symmetric pRFs for D5. We also found relatively larger pRF sizes in D5 and towards the base of the digits.
Mapping Free Water in the Brain Using Multiparameter qMRI Combined with an Iterative Fast Exchange Relaxation Model
Authors: McNaughton Ryan , Hua Ning , Zhang Lei , Kennedy David , Kuban Karl , Jara Hernan
Published: August 2023

Purpose: To develop an integrated theoretical model and computer algorithms for mapping individually and simultaneously the spatial distributions of free water, alongside myelin and iron. Theory: We solve a fast exchange relaxation model effectively decomposing qMRI maps of nPD, R1, and R2 into maps of free water, myelin, and iron. Results: The image processing technique generates maps of free water, myelin, and iron in the brains of adolescents born extremely preterm. Conclusion: A theoretical framework and image processing pipeline for mapping the distribution of free water has been developed and tested with a cohort of adolescents born extremely preterm.
Characterizing exchange dynamics in a urea phantom via T2-T2 relaxometry using a non-linear least squares fitting method
Authors: de A Araujo Ericky Caldas , Marty Benjamin , Reyngoudt Harmen
Published: August 2023

The multiexponential T2 of water in biological tissue is known to reflect microscopic anatomical compartmentation. T2-T2 correlation relaxometry allows characterizing compartmental sizes, intrinsic T2 values and exchange rates, which are of upmost clinical relevance. However, inversion of relaxation data into T2 spectra is an ill-posed problem. Regularized Inverse Laplace transform (rILT) provides stable solutions, but these are penalized by low spectral resolution and relatively high computational complexity. Here we do T2-T2 relaxometry of a urea solution and show that, for such bi-compartment system, non-linear least squares fitting provides solutions that are more accurate while avoiding the difficulties related to rILT.
All you need are DICOM images
Authors: Luo Guanxiong , Blumenthal Moritz , Wang Xiaoqing , Uecker Martin
Published: August 2023

Most deep-learning-based reconstructions methods need predefined sampling patterns and precomputed coil sensitivities for supervised training, limiting their later use in applications under different conditions. Furthermore, only the magnitude images are always stored in DICOM format in the Picture Archiving and Communication System (PACS) of a typical radiology department. That means that raw k-space data is usually not available. This work focuses on how to extract prior knowledge from magnitude images (DICOM) and how to apply the extracted prior to reconstruct images from k-space multi-channel data sampled with different schemes.
The electric potential of lipid vesicle surfaces affects T2 and magnetization transfer
Authors: Min Kyeongseon , Lee Jongho , Park Jang-Yeon
Published: August 2023

In this study, the effect of the electric potential of lipid vesicle surfaces on MR relaxation times and magnetization transfer was investigated. Negatively charged multilamellar vesicles were formed, and their surface potential was adjusted by changing the sodium ion concentration. While the zeta potential changed from -57.0 mV to –21.6 mV, T2 increased from 48.2 ms to 67.4 ms, PSR decreased from 5.5% to 5.0%, kmf decreased from 82.7 Hz to 40.6 Hz, and T2b increased from 177.8 μs to 189.1 μs. These observations are expected to be utilized to image action potential generated in white matter.
Cell swelling induces measurable changes in T2 relaxation time
Authors: Kim Seong-min , Min Kyeongseon , Park Jang-Yeon
Published: August 2023

To find novel contrast mechanisms of neuronal activity, our group previously demonstrated using in vitro cells that changes in membrane potential induces changes in MR parameters. There are two plausible factors that may contribute when the membrane potential changes: the dynamics of hydration water, and cell swelling. In this study, we investigated if cell swelling can contribute to changes in T2 under a constant membrane potential using non-excitable cells. As a result, we found that cell swelling induces measurable changes. As the cell size increased, the short T2 component caused by the intracellular water increased and vice versa.
Iron Imaging with 3D Multi-Gradient Recalled Echo (3D-mGRE) and 3D Ultra-short Echo (3D-UTE) Sequences: A Phantom Comparison Study
Authors: Monsivais Humberto , Shen Xin , Susnjar Antonia , Özen Ali , Ilbey Serhat , Chiew Mark , Karnik Aparna , Emir Uzay , Dydak Ulrike
Published: August 2023

This phantom study aimed to compare a conventional multi-gradient recalled echo (mGRE) sequence and an ultra-short echo (UTE) with a novel 3D rosette k-space trajectory for iron (Fe) detection and quantification. Conventional mGRE imaging may underestimate massive Fe load due to the long echo times (TEs). Advanced UTE techniques with TEs 10-200 times shorter than conventional mGRE sequences can capture fast signal decay caused by high Fe content. Our preliminary results show that both sequences yield a strong linear relationship between R2* values and Fe concentrations, with the 3D-UTE results aligning more with expected R2* values for high Fe concentrations.
Impact of Coupling on the B1+ Field Produced by a 15-panel Tic-Tac-Toe RF Array
Authors: Sajewski Andrea , Santini Tales , DeFranco Anthony , Martins Tiago , Berardinelli Jacob , Aizenstein Howard , Ibrahim Tamer
Published: August 2023

We investigated the impact of coupling (magnitude and phase) on the B1+ field distribution and intensity of a 30-channel double-rowed Tic-Tac-Toe (TTT) RF array. We found that by changing the coupling of the TTT coil modules, we are able to modify the B1+ distribution from a single channel and how the B1+ field intensity is spread between different Z levels of the 30-channel array. This effect was seen in both simulations and experimental B1+ maps.
Second resonance mode ensure intrinsic low coupling between elements on shielded-coaxial-cable coil designs
Authors: Güler Sadri , Zhurbenko Vitaliy , Zivkovic Irena , Boer Vincent , Petersen Esben
Published: August 2023

The recent introduction of the flexible shielded-coaxial-cable coils (SCC) and their intrinsic high degree of decoupling between elements make them ideal for multichannel transceiver arrays needed for improved field homogeneity at ultra-high field MRI. In this work, we show the mode of operation of the SCC and that the selection of its second resonance mode is crucial to obtain its intrinsic high degree of decoupling between elements. We obtained this insight using both numerical simulations and an equivalent circuit model, which can guide to optimal SCC designs in the future.
Resting-state Functional connectivity to differentiate Mild Cognitive Impairment, Alzheimer's disease, and Normal subjects
Authors: Mohammadian Fatemeh , Noroozian Maryam , Sadeghi Arash Zare , Salari Hanieh Mobarak , Hashemi Hassan , Rad Hamid Reza Saligheh
Published: August 2023

Millions of people around the world suffer from Alzheimer's disease (AD), the most common neurodegenerative disease. Due to the progressive cognitive decline of the disease, early diagnosis can play an important role in the treatment and prevention of disease progression. Because functional and physiological changes occur before structural changes, functional imaging-based biomarkers such as Functional connectivity (FC) can show these changes well.
One-stop subtractionless first-pass CS-whole-body MRA with once contrast injection of 0.15mmol/kg dose: first clinical experience
Authors: FU Qing , Wu Jia-wei , Li Jing-yang , Sun Peng , Kong Xiang-chuang
Published: August 2023

Conventional subtracted whole-body CE-MRA is time-consuming and requires experiences for operators. Instead, one-stop subtractionless CS-MRA in our study could depict the whole-body arterial vasculatures with only once contrast injection and only 0.15 mmol/kg dose, which assisted by multiple techniques including reverse k-space filling mode, total imaging matrix system, automatic table moving, automatic coil selection and especially the CS technique. The comparative results supported it feasible with accepted image qualities and a faster acquisition time in clinical use.
Investigating the clinical viability of a control system-based slice-following sequence for free-breathing cardiovascular DTI
Authors: Jermy Stephen , Tunnicliffe Elizabeth , Ntusi Ntobeko , Meintjes Ernesta
Published: August 2023

A prospective respiratory motion correction control system, capable of slice-following, was tested on a 3 T clinical MRI scanner. The performance of the control system was compared against the most common respiratory motion compensation technique, namely multiple breath-holds. Both techniques produced similarly consistent results. The control system technique was able to reduce the acquisition time by acquiring data with 100% respiratory efficiency
Fat-free MRI with fast and power-optimized off-resonant LIBOR pulses
Authors: Bastiaansen Jessica , Piccini Davide , Mackowiak Adele
Published: August 2023

Flexible off-resonant RF pulse designs such as LIBRE and BORR are inspired by conventional binomial 1-(180)-1 water excitation pulses and perform better in terms of fat suppression. To abbreviate scanning times, BORR and LIBRE pulse durations can be shortened by increasing the RF excitation frequency at the expense of increased RF power. To reduce RF power, we developed a novel off-resonant RF pulse design based on the conventional 1-(90)-1 water excitation pulse. LIBOR, compared with LIBRE and BORR, reduced the required RF power while maintaining short pulse durations and effective fat suppression in simulations, knee, and cardiac MRI at 3T.
3D Whole Heart Grey-blood PSIR Imaging After Slow Infusion and Bolus Injection for High-resolution Isotropic LGE Imaging
Authors: Schneider Alina , Hajhosseiny Reza , Munoz Camila , Milotta Giorgia , Kunze Karl P , Neji Radhouene , Chiribiri Amedeo , Masci Pier Giorgio , Botnar René M , Prieto Claudia
Published: August 2023

3D whole-heart free breathing water/fat non-rigid motion corrected grey-blood PSIR LGE technique has been recently proposed showing good agreement with conventional 2D grey-blood LGE MRI. Due to the relatively long scan time of ~10 minutes, contrast washout may influence scar detection and limit spatial resolution. Here we compare the proposed 3D grey-blood PSIR LGE after slow infusion and bolus injection at high isotropic spatial resolution to evaluate the benefit of the slow infusion injection. Both pipelines were compared to the conventional breath-held 2D grey blood PSIR-LGE imaging technique. Overall higher quality scores were observed in images acquired after slow infusion.
Interventional continuous cardiac thermometry via simultaneous catheter tracking and undersampled radial golden angle acquisition
Authors: Yon Maxime , Delcey Marylène , Bour Pierre , Grissom William , Quesson Bruno , Ozenne Valéry
Published: August 2023

Interventional MR thermometry has the potential to increase the success rate of the radio-frequency cardiac ablative procedure by allowing real-time monitoring of the lesion growth. Available methods are dependent on ECG-gating, which is poorly reliable in arrhythmic conditions. We propose a new approach based on radial continuous gradient echo acquisition combined with concomitant 2D intra-scan motion correction and direct estimation of the temperature from k-space data which could be a robust alternative to the more classical but ECG-triggered and artifact-prone EPI methods.
Interleaved radial linear combination SSFP for improved cine imaging with implanted cardiac devices
Authors: Xiang Jie , Lamy Jerome , Lampert Rachel , Peters Dana
Published: August 2023

Interleaved undersampled radial linear-combination balanced SSFP (LC-SSFP) was investigated as a method for improving cardiac cine images, acquired in subjects with metallic implants. Phantoms and healthy volunteer studies were performed, in the presence of metallic artifacts (generated by a stainless steel bolt). We found the proposed method eliminated some artifacts seen using standard Cartesian bSSFP. These findings may lead to improved cardiac cine imaging for patients with a pacemaker or implantable cardioverter defibrillator (ICD).
Accuracy of quantitative DCE-MRI depends on the implementation of the convolution operation
Authors: Ahmed Zaki , Levesque Ives
Published: August 2023

Quantitative DCE-MRI analysis requires fitting a model to the acquired enhancing time-course data. These models involve a convolution operation, which has a variety of possible implementations. The goal of this work was to evaluate three different implementations of the convolution operation: (i) Fourier, (ii) Summation, (iii) Iterative. The accuracy and execution time of each implementation was compared on a virtual phantom. It was found that the iterative technique was the fastest while also having the best overall accuracy.
The effect of k-space sampling patterns on contrast agent uptake curves in dynamic contrast-enhanced MRI of the breast
Authors: White Owen , Kousi Evanthia , Sanders Clarrissa , Schmidt Maria
Published: August 2023

Here we propose a novel method to assess the effect of different k-space sampling patterns on contrast agent uptake curves (CAUCs), which does not require specialist equipment. These effects on CAUCs are often overlooked, and must be addressed in the context of the many different national and international recommendations, and the prominence given to abbreviated DCE protocols. We validated the method to assess different k-space sampling patterns and used it to simulate the effect on contrast-agent uptake curves. We show that conventional protocols acquiring each frame in approximately 60s have more robust CAUC classification than abbreviated protocols.
Assessment of the Diagnosis Value of Diffusion Tensor Imaging and Fractional Anisotropy Value in Peripheral Prostate Cancer based on PI-RADS v2
Authors: Chen Zhiqiang , Song Na , Zhang Dan , Wang Zhuo , Zhang Shaoru , Xiong Yuhui , Wang Aijun , Chen Bing , Cai Lei
Published: August 2023

In this retrospective study, we aim to explore the diagnostic values of diffusion tensor imaging (DTI) in peripheral prostate cancer, and compare DTI with diffusion weighted imaging (DWI) based on prostate imaging reporting and data system version 2 (PI-RADS v2) in peripheral prostate cancer (PCa). It was concluded that both DWI and DTI have high values in the diagnosis and differentiation of PCa, and DWI& dynamic contrast enhanced (DCE) MRI has higher diagnostic efficiency than DTI&DCE-MRI according to PI-RADS v2.
Applying L+S decomposition to improve sensitivity to dynamic changes in functional MR spectroscopy
Authors: Berrington Adam , Ip I. Betina
Published: August 2023

Functional MRS (fMRS) is a powerful technique to measure metabolite responses over time. However, noise and spectral contamination limit the ability to study individual metabolite time-courses. In this work, we propose to model fMRS spectra as a superposition of low-rank (L) and sparse components (S). L+S decomposition resulted in separation of temporally-correlated signal from noise in simulation. In vivo, L+S spectra had higher SNR compared to original data (P=0.007) and the mean glutamate time-course, using L+S spectra, was more strongly correlated to stimulus. L+S decomposition is a promising data-driven method to enhance sensitivity to dynamic changes in fMRS.
Fast 3D DCE MRI using partially separable model: autopilot Multitasking
Authors: Lyu Jingyuan , Liu Qi , Ding Yu , Xu Jian , Gong Xiaomao , Zhang Weiguo , Rao Shengxiang , Wang Wentao , Zeng Mengsu
Published: August 2023

Inspired by Multitasking, we have developed a fast reconstruction method for 3D stack-of-star (SoS) acquisitions to achieve high temporal resolution (0.1s) DCE MRI without additional navigator data. The proposed method is fully compatible with existing sequence using 3D SoS trajectories, but with less computation complexity.
Spiral 3DREAM sequence for fast whole-brain B1 Mapping
Authors: Veldmann Marten , Niesen Svenja , Ehses Philipp , Stöcker Tony
Published: August 2023

The 3DREAM sequence provides a fast technique for whole-brain B1 mapping, but suffers from different blurring levels in FID and STE* images. We developed a new variant of the 3DREAM sequence with a spiral readout to mitigate this problem. The spiral readout shortens the echo train duration and reduces the number of excitations after the STEAM preparation significantly. This leads to similar blurring levels in FID and STE* images and increases the effective resolution of flip angle maps. As a result, correction strategies for different blurring levels are no longer necessary.
Spiral UTE MRI of the Lung: An Investigation on Motion Sensitivity
Authors: Fauveau Valentin , Jacobi Adam , Bernheim Adam , Chung Michael , Yang Yang , Benkert Thomas , Fayad Zahi , Feng Li
Published: August 2023

Spiral UTE is a relatively new MRI technique that combines ultra-short echo time acquisition with a stack-of-spirals trajectory for imaging the lung. In this work, we aimed to analyze the motion sensitivity of different reordering schemes and breath holding positions in spiral UTE MRI to determine the optimized protocol for imaging the lungs. A blind assessment was performed by three experienced chest radiologists and the results were analyzed with statistical tests. The Spiral UTE with line-in-partition reordering performed during the inspiration phase was considered the best protocol in our study.
Effects of T2*-blurring on effective resolution of diffusion MRI with spiral and EPI readout trajectories at 7T
Authors: Feizollah Sajjad , Tardif Christine
Published: August 2023

Several strategies have been used to increase the SNR of diffusion-weighted imaging including the use of partial Fourier EPI and spiral trajectories. Although these methods increase the SNR and sequence efficiency significantly, they affect the image quality and resulting diffusion measures causing loss of microstructural information of fine structures. Blurring caused by the T2* decay is one of the important effects resulting in low effective resolutions. Shorter T2* at ultra-high magnetic fields reduces the effective resolution in spite of providing higher SNR. This study shows about 60% lower effective resolution than the nominal resolution using PF-EPI and spiral at 7T.
Multishot EPI and a Deep Learning-Based Noise Reduction Strategy for High Resolution Pancreatic DWI
Authors: Middione Matthew , Moalem Alimohammad , Hong Cheng , Guidon Arnaud , Ennis Daniel B. , Brunsing Ryan
Published: August 2023

DWI of the pancreas is challenging due to artifacts from physiologic motion, image distortion, and blurring, but has promising applications in pancreatic cancer detection. We conducted a pilot study of pancreatic DWI comparing single-shot and multi-shot EPI protocols as well as multi-shot EPI protocols with and without a new commercially available deep learning (DL) based denoising reconstruction method. Image quality was subjectively scored with key metrics. Multi-shot EPI reduced perceived distortion within the pancreatic bed, while the combination of multi-shot EPI and DL reconstruction subjectively reduced noise.
In vivo CEST imaging of Glutamate and myo-Inositol for early-stage changes in Alzheimer’s 5xFAD mouse model
Authors: Nanga Ravi Prakash Reddy , Juul Halvor , Soni Narayan Data , Benyard Blake , Swain Anshuman , Armbruster Ryan , Jacobs Paul , Reddy Ravinder
Published: August 2023

In order to probe the metabolism of glutamate and myo-inositol for better understanding of the Alzheimer’s diseases (AD) we have employed the chemical exchange saturation transfer of glutamate (GluCEST) and myoinositol (MICEST) in a fast progressing, 5xFAD mouse model. There were significant differences observed in the GluCEST and MICEST maps of 5XFAD mice when compared to the wild-type (WT) mice for regions of interest drawn on hippocampus and thalamus, which are further supported by the spectroscopy results.
Associations of Aging- and AD-associated 7T MRS Neurochemical Profiles with Cognition and Polygenic Risk for AD
Authors: Wolf Michael , Cruchaga Carlos , Crocker Jillilan , Gorijala Priyanka , Hemmy Laura , Hodges James , Mafimoghaddam Samira , Mangia Silvia , Marjanska Malgorzata , McCarten Riley , Nichols Thomas , Thotland Jeromy , Zilinskas Rachel , Terpstra Melissa
Published: August 2023

Ultra-high field (7T) ultra-short echo time (8 ms STEAM) MRS can consistently provide a 14-neurochemical profile and distinguish aging and AD status. In this project, we generated composite scores from published age- and AD- specific neurochemical profiles and applied them to a typically aging cohort for whom polygenic risk for AD and extensive cognitive performance data were also available. Principal component analysis of the neurochemical profile fully distinguished aging, and AD classification was 58% correct. The largest correlation coefficients (r) were found between MRS and cognition. Correlation between MRS and polygenic risk and between cognition and polygenic risk was smaller.
MRSI DETECTABLE CHOLINE METABOLISM AS MARKER FOR GENDER DIFFERENCES IN AGING
Authors: Pilatus Ulrich , Eckert Gunter , Ludin Nasir , Matura Silke , Pantel Johannes , Silaidos Carmen , Wachter Lena , Hattingen Elke
Published: August 2023

Combining quantitative (mmol/l) 1H MRSI and 31P MRSI data from the brain of healthy volunteers revealed a choline component (rCho=tCho-(PCho+GPC)) which is visible with 1H MRSI but missing in 31P MRSI. This component, which may account for a fraction of mobile phospholipids, is reduced in young female (mean age 26) subjects. Lower levels would indicate a higher integrity of the membrane phospholipids in the brain of young women. A possible reason is the higher estrogen levels in this group.
7T multi-pool CEST MRI in multiple sclerosis patients
Authors: Fabian Moritz , Hock Stefan , Mennecke Angelika , Schmidt Manuel , Dörfler Arnd , Zaiß Moritz
Published: August 2023

Differentiation of active multiple sclerosis lesions from non-active ones is done in the clinical environment by using contrast enhanced T1 images. CEST MRI has shown to yield correlations with Gadolinium contrast enhancement in tumors and other pathological tissue. In this work, we are trying to gain more insight in the metabolic information regarding the brain of patients suffering from multiple sclerosis.
In vivo myelin water imaging at 0.55T
Authors: Schäper Jessica , Bieri Oliver
Published: August 2023

Myelin water fraction (MWF) imaging is an important tool to investigate demyelination in WM. When using GRE sequences, the method suffers from T2* effects, leading to a non-exponential behaviour. This can potentially influence the calculation of MWF. At low fields susceptibility effects are less and the assumption of biexponential T2-decay is more accurate. Here, the feasibility of MWF at 0.55 T, using biexponential fitting was demonstrated.
Orientation dependence of local frequency difference and R2* in parallel versus crossing fibers at 3T and 7T
Authors: Chen Lin , Mao Deng , Gilbert Guillaume , Versluis Maarten , van Zijl Peter , Li Xu
Published: August 2023

We investigated the dependence of local frequency difference Δf and R2* on the fiber orientation with respect to the static field in selected parallel-fiber and crossing-fiber regions at 3T and 7T. Δf and R2* showed consistent relationship (sin2θ and sin4θ ) with average ROI-based fiber-to-field angle θ at 3T and 7T. Larger amplitude of variations in Δf and R2* with respect to θ were observed in parallel-fiber compared with crossing-fiber regions indicating non-negligible contributions from fiber orientation dispersion to the nonlinear gradient echo signal evolution and related MRI measures sensitive to white matter microstructure.
SLAM reconstruction of 31P Cardiac MRS Improves PCr/ATP Repeatability Without Requiring Cardiac Gating
Authors: Tyler Andrew , Hundertmark Moritz , Miller Jack , Rider Oliver , Tyler Damian , Valkovic Ladislav
Published: August 2023

Using the SLAM algorithm to reconstruct non-gated acquisition weighted 31P cardiac CSI data-sets improved repeatability by 35% and reduced variation by 23%, compared to a Fourier based reconstruction of the same data-set, without requiring a change to acquisition protocol.
Rapid and Robust Assessment of Circumferential Strain Recovery via Tagged MRI of Infarcted Pig Hearts After Human Cardiomyocyte Transplantation
Authors: Naumova Anna , Kerwin William
Published: August 2023

A new straight forward approach for rapid and robust quantification of myocardial circumferential strain has been developed. The key to this method is placement of the linear tags in 60-degree pattern offsets and alignment of the tags with the AHA segments for optimized segmental analysis. The approach has been implemented for the first time for evaluation of the human cardiomyocyte transplantation benefits in the infarcted pig heart. We have shown the temporal changes in circumferential strain and strain rate of the infarcted segments of myocardium and recovery of myocardial strain followed human cardiomyocyte transplantation in comparison with untreated control group.
Active Catheter Tracking Error Characterization for Minimally Invasive MR-Guided Cardiac Interventions
Authors: Gupta Arjun , Biswas Labonny , Soni Jay , Coles Brandon , Ferguson Sebastian , Wright Graham , Ghugre Nilesh
Published: August 2023

Minimally invasive cardiac interventions, such as ablation treatment for ventricular tachycardia and therapy delivery involving biologics (cells, genes, biomaterials) for the treatment of myocardial infarction, require a tracking accuracy of <5mm. Our study aimed to characterize the spatial error associated with MR-guided active catheter tracking under static conditions. In a 1.5T MR scanner, we tracked an ablation catheter at 48 different positions, all confined within the boundaries of where a typical human heart would be located. We found that the error was both minimized and maintained below our 5mm target when using a Hadamard multiplexed active tracking sequence.
Rapid Variable Flip-angle T2 Quantification (RavFa-T2) of the Myocardium using Steady-state Free Precession: A Two-Center Study
Authors: Marquet Céline , Jang Jihye , Powell Andrew , Fonseca Brian , Browne Lorna , Moghari Mehdi
Published: August 2023

We developed a novel method (RavFa-T2) for T2 quantification of myocardium using transient steady-state free precession (SSFP) with a variable flip angle scheme. RavFa-T2 was systematically analyzed based on a phantom and a two-center patient study. We show that RavFa-T2 yields accurate T2 estimates for the myocardium compared to the state-of-the-art method T2-Prep and reduces scan time to ≤4 seconds.
In Vivo Clinical Cardiac DTI in 5 minutes
Authors: Teh Irvin , Kelly Christopher , Shelley David , Poenar Ana-Maria , Plein Sven , Dall'Armellina Erica , Nguyen Christopher , Schneider Jürgen E.
Published: August 2023

There is strong interest in characterising the cardiac microstructure using in vivo cardiac diffusion tensor imaging (CDTI). However, its use in larger clinical studies is often hampered by long scan times. We sought to rationalise the scan parameters needed for a clinically feasible CDTI protocol, by comparing carefully subsampled data against a 24-minute reference dataset. A design strategy was identified based on maximising the number of diffusion-weighting (DW) directions, subject to minimum SNR requirements. Feasibility of a 5-minute protocol was demonstrated where NRMSE(MD) = 5.2±0.2%, NRMSE(FA) = 12.8±0.2%, RMSE(HA) = 5.5±0.4°, RMSE(absE2A) = 15.7±1.9°.
Accuracy of left ventricular function measurements using retro-gated real-time cine bSSFP cardiovascular magnetic resonance
Authors: Statton Ben , Berry Alaine , Kellman Peter , Xue Hui , Cook Stuart , O'Regan Declan
Published: August 2023

Cardiac magnetic resonance with a retrospective ECG-gated breath-hold cine stack is the reference standard for assessing LV volumes, however this technique is unsuitable for patients who cannot hold their breath or suffer arrhythmia. A potential solution is a “retro-gated” real-time sequence which is prospectively triggered to acquire 120 frames over multiple heartbeats in each slice. Images from a beat most closely matching the median beat length for the entire stack are then temporally interpolated to 30 output phases for each slice. This retro-gated method showed good agreement with the reference standard sequence in a cohort of healthy volunteers.
Vascular supply affects hemodynamic responses to a hypercapnia cerebrovascular reactivity challenge assessed by BOLD-fMRI
Authors: Marchena-Romero Kayley , Ji Xiang , Centen Andrew , Sommer Rosa , Ramirez Joel , Thrippleton Michael , Lim Andrew , Wardlaw Joanna , Black Sandra , MacIntosh Bradley
Published: August 2023

Cerebrovascular reactivity (CVR) is a dynamic assessment of hemodynamic response during hypercapnia. Conventional CVR metrics provide a single estimate to summarize the dilatory response to CO2. We propose to isolate dilation and constriction responses to a CVR challenge measured by BOLD-fMRI and assess the effect of vascular supply on vasoreactivity. We show that vascular supply affects the hemodynamic response to hypercapnia, and that this effect varies over time in different clinical cohorts. This work suggests that the extraction of individual features embedded in a CVR challenge can help characterize cerebrovascular physiology in unique clinical cohorts.
Repeatability of cerebrovascular reactivity amplitude and timing estimates using a sinusoidal manipulation of end-tidal CO2
Authors: Stickland Rachael , Zvolanek Kristina , Bright Molly
Published: August 2023

We assessed the repeatability of fMRI Cerebrovascular Reactivity (CVR) estimates using CO2 sinusoidal stimuli. We estimated BOLD-CVR amplitude and phase using a fast Fourier transform (FFT) analysis and a cross-correlation analysis (Rapidtide). Amplitude and delay maps showed sensible regional variations for both time-points, but participant variability was notable. CVR spatial correlations between time-points were higher after averaging within cortical parcels, compared to weak voxel-wise correlations. Qualitatively, Rapidtide achieved higher between-session correlations than FFT. GM average amplitudes agreed between time-points. At the correct spatial scale, with careful consideration of parameter scaling, this short stimulus is a viable CVR mapping option.
Neuronal modulation in cerebrovascular reactivity measurements using a breath-hold task: a simultaneous EEG-fMRI study
Authors: Esteves Inês , Raposo Beatriz , Xavier Marta , Fouto Ana R. , Ruiz-Tagle Amparo , Domingos Catarina , Vourvopoulos Athanasios , Silva Nuno A. , Nunes Rita G. , Gil-Gouveia Raquel , Rosa Agostinho , Figueiredo Patrícia
Published: August 2023

fMRI can be used to assess cerebrovascular reactivity by measuring BOLD changes during a breath hold task. This is assumed to be isometabolic so that BOLD changes cannot be attributed to neuronal activity. We performed simultaneous EEG-fMRI recordings during a breath-hold task to assess to what extent neuronal activity retrieved from the EEG may contribute to explain the BOLD signal variance that is usually interpreted as reactivity. We found that neuronal modulation measured by EEG band power did not explain significantly more BOLD variance across GM than PetCO2 changes, indicating that the associated fMRI measurements truly reflect cerebrovascular reactivity.
Repeatability of the BOLD-CVR experiment at 3 T with fixed inspired CO2 concentration gas stimulus
Authors: Sleight Emilie , Stringer Michael , Murphy Madeleine , Mitchell Isla , Marshall Ian , Wardlaw Joanna , Thrippleton Michael
Published: August 2023

The BOLD response to a gas with fixed inspired CO2 concentration is commonly used to assess the health of the cerebral vasculature. Cerebrovascular reactivity (CVR) magnitude repeatability has been assessed in previous studies, but without reporting potential physiological confounders such as heart and respiration rates. Furthermore, less is known about CVR delay repeatability. In this work, we assessed the within-day test-retest repeatability of both quantities in healthy volunteers at 3 T while measuring the heart and respiration rates. We found that both show good repeatability, though CVR delay estimates are unreliable in tissues with low contrast to noise ratio.
In vivo mapping of sodium relaxation times in breast fibroadenoma at 7T
Authors: Ianniello Carlotta , Brown Ryan , Moy Linda , Fogarty Justin , Schnabel Freya , Axelrod Deborah , Madelin Guillaume
Published: August 2023

Sodium (23Na) MRI has been employed to measure the total sodium concentration (TSC) in breast lesions, which is often elevated compared to healthy breast. The knowledge of the 23Na relaxation times of the breast, which could be subject to variations in lesions, could increase the accuracy of TSC estimation. In this work we measured the 23Na relaxation times in six fibroadenoma patients and found a 71% increase in T2,s and a 28% decrease in T1 in the lesions compared to healthy tissue. Therefore, using healthy breast relaxation times in TSC quantification could result in errors in lesions.
Automated breast segmentation using deep-learning in water-fat breast MRI: application to breast density assessment
Authors: Somasundaram Arun , Wu Mingming , Borde Tabea , Makowski Marcus , Fallenberg Eva , Zhao Yu , Karampinos Dimitrios
Published: August 2023

Conventional methods for semi-automatic and rule-based breast segmentation on MR images have a tradeoff between accuracy and segmentation speed. To overcome this, several 2D-deep learning approaches have been proposed, which usually focus on using T1-weighted images to train their models. Our aim is to train a 3D-network for breast segmentation, trained on water-fat MR images, which can be used to measure the breast density based on the proton density fat fraction (PDFF). We show that our model segments both fast and accurately, and can visually outperform our ground truth segmentations while requiring only a few seconds to generate labels.