Magalie Viallon

• PhD
• MR physicist at Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé, French National Centre for Scientific Research

The diffusion process in the myocardium is difficult to investigate because of the unqualified sensitivity of diffusion measurements to cardiac motion. We introduced a mathematical formalism to quantify the effect of tissue motion on the diffusion NMR signal. The presented model is based on the Bloch-Torrey equations and takes into account the card...

Major progress has recently been made in the neuro-imaging of stroke as a result of improvements in imaging hardware and software. Imaging may be based on either magnetic resonance imaging (MRI) or computed tomography (CT) techniques. Imaging should provide information on the entire vascular cervical and intracranial network, from the aortic arch t...

Motion‐induced shot‐to‐shot phase variation and strong image aliasing artifacts are common in diffusion weighted imaging (DWI) multi‐shot EPI (MS‐EPI). Herein, motion‐compensated diffusion encoding waveforms were used to minimize shot‐to‐shot phase variation, and an MS‐EPI with Keyhole (MS‐EPIK) trajectory was evaluated to mitigate image aliasing....

Background Fasting shows promise for public health, but concerns about muscle loss hinder its acceptance, particularly among the elderly. We explored the impact of long‐term fasting (12 days, 250 kcal/day) on muscle structure, metabolism and performance. Methods We prospectively assessed muscle volume, composition, relaxometry data and lipid metab...

Background: In adults, epicardial adipose tissue (EAT) is associated with metabolic syndrome (MS) and coronary artery disease. EAT thickness is increased in obese youth, but total EAT volume and its correlation with cardiovascular risk factors have not been studied. Objectives: To determine EAT volume in adolescents and its association with obesity...

Thanks to recent developments in cardiovascular magnetic resonance (CMR), cardiac diffusion-weighted magnetic resonance is fast emerging in a range of clinical applications. Cardiac diffusion-weighted imaging (cDWI) and diffusion tensor imaging (cDTI) now enable investigators and clinicians to assess and quantify the tridimensional microstructure o...

Objectives: The non-linear relationship between gadolinium concentration and the signal in perfusion cardiac magnetic resonance (CMR) poses a significant challenge for accurate quantification of pharmacokinetic parameters. This phenomenon primarily impacts the arterial input function (AIF), causing it to appear saturated in comparison to the tempor...

In this second part of a two‐part paper, we intend to demonstrate the impact of the previously proposed advanced quality control pipeline. To understand its benefit and challenge the proposed methodology in a real scenario, we chose to compare the outcome when applying it to the analysis of two patient populations with significant but highly differ...

Implementing a standardized phosphorus‐31 magnetic resonance spectroscopy ( ³¹ P‐MRS) dynamic acquisition protocol to evaluate skeletal muscle energy metabolism and monitor muscle fatigability, while being compatible with various longitudinal clinical studies on diversified patient cohorts, requires a high level of technicality and expertise. Furth...

This work presents a fast and simple method based on spiral MRSI for mapping the IMCL and EMCL apparent content, which is a challenging task and it compares this indicator to classical quantification results in muscles of interest.

Objectives Myocardial injury assessment from delayed enhancement magnetic resonance images is routinely limited to global descriptors such as size and transmurality. Statistical tools from computational anatomy can drastically improve this characterization, and refine the assessment of therapeutic procedures aiming at infarct size reduction. Based...

Purpose: To develop a three-dimensional (two dimensions + time) convolutional neural network trained with displacement encoding with stimulated echoes (DENSE) data for displacement and strain analysis of cine MRI. Materials and methods: In this retrospective multicenter study, a deep learning model (StrainNet) was developed to predict intramyoca...

Introduction: Cardioprotection strategies remain a new frontier in treating acute myocardial infarction (AMI), aiming at further protect the myocardium from the ischemia-reperfusion damage. Therefore, we aimed at investigating the mechano-transduction effects induced by shock waves (SW) therapy at time of the ischemia reperfusion as a non-invasive...

Abstract Background While multiple cardiovascular magnetic resonance (CMR) methods provide excellent reproducibility of global circumferential and global longitudinal strain, achieving highly reproducible segmental strain is more challenging. Previous single-center studies have demonstrated excellent reproducibility of displacement encoding with st...

Fasting provokes fundamental changes in the activation of metabolic and signaling pathways leading to longer and healthier lifespans in animal models. Although the involvement of different metabolites in fueling human fasting metabolism is well known, the contribution of tissues and organs to their supply remains partly unclear. Also, changes in or...

In the last decade, a large number of clinical trials have been deployed using Cardiac Magnetic Resonance (CMR) to evaluate cardioprotective strategies aiming at reducing the irreversible myocardial damage at the time of reperfusion. In these studies, segmentation and quantification of myocardial infarct lesion are often performed with a commercial...

Objectives The effects of ultra-distance on cardiac remodeling and fibrosis are unclear. Moreover, there are no data reporting the kinetics of cardiac alterations throughout the event and during recovery. Our aim was to investigate the kinetics of biological markers including new cardiac fibrosis biomarkers suppression of tumorigenicity 2 (ST2) and...

We aim at better understanding the mechanisms of ischemia and reperfusion, in the context of acute myocardial infarction. For this purpose, imaging and in particular magnetic resonance imaging are of great value in the clinic, but the richness of the images is currently under exploited. In this paper, we propose to characterize myocardial ischemia...

Introduction: Cardiac diffusion tensor imaging (DTI) is an emerging technique for the in vivo characterisation of myocardial microstructure, and there is a growing need for its validation and standardisation. We sought to establish accuracy, precision, repeatability and reproducibility of state-of-the-art pulse sequences for cardiac DTI between te...

Background The formation of cardiac fibroid deposits due to intense exercise may be involved in cardiac arrhythmias. Galectin-3 (Gal-3) and suppression of tumorogenicity2 (ST2) are considered as markers for fibrosis development and cardiac remodeling. Objective The aim of our study was to examine the evolution of both in trailers who ran the Tor d...

This paper deals with acceleration of multidimensional signal acquisition. The signal is assumed to have multiple discrete spatial dimensions where each point is time varying. The one-dimensional Fourier transform of the time evolution of each point is assumed to have an a priori known bounded support. The Fourier transform of the spatial domain...

Cardiac magnetic resonance myocardial perfusion imaging can detect coronary artery disease and is an alternative to single-photon emission computed tomography or positron emission tomography. However, the complex, non-linear MR signal and the lack of robust quantification of myocardial blood flow have hindered its widespread clinical application th...

Extreme ultra-endurance races are growing in popularity but their effects on skeletal muscles remain mostly unexplored. This longitudinal study explores physiological changes in mountain ultramarathon (MUM) athletes' quadriceps using quantitative magnetic resonance imaging (qMRI) coupled with serological biomarkers. The study aimed to monitor the l...

Background and objective: The prevention of ascending thoracic aortic aneurysms (ATAAs), which affect thousands of persons every year worldwide, remains a major issue. ATAAs may be caused by anything that weakens the aortic wall. Altered hemodynamics, which concerns a majority of patients with bicuspid aortic valves, has been shown to be related t...

Purpose Myofiber strain, Eff, is a mechanistically relevant metric of cardiac cell shortening and is expected to be spatially uniform in healthy populations, making it a prime candidate for the evaluation of local cardiomyocyte contractility. In this study, a new, efficient pipeline was proposed to combine microstructural cDTI and functional DENSE...

Guidelines for the treatment of aortic wall diseases are based on measurements of maximum aortic diameter. However aortic rupture or dissections do occur for small aortic diameters. Growing scientific evidence underlines the importance of biomechanics and hemodynamics in aortic disease development and progression. Wall shear stress (WWS) is an impo...

Myocardial interstitial fibrosis is part of the advanced disease stage of most cardiovascular pathologies. It has been characterized histologically in various disease settings from hypertensive heart disease and diabetic cardiomyopathy to severe aortic stenosis. It is also involved in the process of aging. In cardiovascular medicine, myocardial int...

Cardiac diffusion tensor imaging (DTI) is increasingly used for non-invasive in vivo characterisation of cardiac microstructure. To help reconcile the variation in DTI metrics in the literature, we investigated the inter- and intra-site variation of DTI across twelve clinical scanners. Data were acquired at two time points, with a standardised isot...

In this paper, we evaluate computationally the influence of blood flow eccentricity and valve phenotype (bicuspid (BAV) and tricuspid (TAV) aortic valve) on hemodynamics in ascending thoracic aortic aneurysm (ATAA) patients. 5 TAV ATAA, 5 BAV ATAA (ascending aorta diameter > 35 mm) and 2 healthy subjects underwent 4D flow MRI. The 3D velocity profi...

Cardiac diffusion tensor imaging (DTI) is increasingly used for non-invasive in vivo characterisation of cardiac microstructure. To help reconcile the variation in DTI metrics in the literature, we investigated the inter-and intra-site variation of DTI across twelve clinical scanners. Data were acquired at two time points, with a standardised isotr...

Ascending thoracic aortic aneurysms (ATAA) are a permanent dilation associated with a high risk of aortic rupture or dissection and death of the patient. It is the 17th most common cause of death, affecting approximately 10 out of 100,000 persons per year. The alteration in the blood flow dynamics is found to be one of the major cause for aortic di...

The cover image is based on the Original Article Computational prediction of hemodynamical and biomechanical alterations induced by aneurysm dilatation in patient‐specific ascending thoracic aortas by Stéphane Avril, Raja Jayendiran, Francesca Condemi, et al., https://doi.org/10.1002/cnm.3326.

The aim of the present work is to propose a robust computational framework combining computational fluid dynamics (CFD) and 4D flow MRI to predict the progressive changes in hemodynamics and wall rupture index (RPI) induced by aortic morphological evolutions in patients harboring ascending thoracic aortic aneurysms (ATAAs). An analytical equation h...

Background: The T1 Mapping and Extracellular volume (ECV) Standardization (T1MES) program explored T1 mapping quality assurance using a purpose-developed phantom with Food and Drug Administration (FDA) and Conformité Européenne (CE) regulatory clearance. We report T1 measurement repeatability across centers describing sequence, magnet, and vendor...

Background After acute myocardial infarction (AMI), reperfusion injury is associated with microvascular lesions and myocardial edema. Purpose To evaluate the performance of apparent diffusion coefficient (ADC) quantification compared with T1 and T2 values in the detection of acute myocardial injury. Materials and Methods In this prospective study c...

Objective: Muscle atrophy is frequent in critically ill patients and is associated with increased mortality and long-lasting alteration in quality of life. Muscle ultrasound has not been clearly validated in intensive care unit patients. The aim of this study was to compare the level of agreement between ultrasound and computed tomography scan for...

Cardiac diffusion tensor imaging (DTI) continues to develop as a non-invasive contrast-free method for in vivo characterization of cardiac microstructure. Currently, data from healthy subjects 1,2,3,4 report a wide range for both mean diffusivity (MD, 0.75 × 10-3 to 1.72 × 10-3 mm 2 /s) and fractional anisotropy (FA, 0.29 to 0.61). Consequently, th...

In this study, segmentation of quadriceps muscle heads of ultra-endurance athletes was done using a multi-atlas segmentation and corrective leaning framework where the registration based multi-atlas segmentation step was replaced with weakly supervised U-Net. For the case with remarkably different morphology, our method produced improved accuracy,...

Goal: Ascending thoracic aortic aneurysm (aTAA) is a major cause of human deaths. Despite important recent progress to better understand its pathogenesis and development, the role played by deranged hemodynamics on aTAA risk of rupture is still partially unknown. Our aim was to develop and apply a novel methodology to assess the correlation between...

Aneurysm rupture is the most common cause of mortality and there are about 20,000 people in Europe and 10,000 people in the United States are diagnosed with ascending thoracic aortic aneurysm (ATAA) [1,2]. Blood flow dynamics are found to be one of the main factors for aortic dissection. Imaging techniques such as computed tomography (CT) and magne...

High frame rate imaging is particularly important in echocardiography for a better assessment of the cardiac function. Several studies showed that Diverging Wave Imaging (DWI) and Multi Line Transmit (MLT) are promising methods for achieving a high temporal resolution. The aim of this study was to compare MLT and compounded motion compensated (MoCo...

This work aims at assessing the impact of ascending thoracic aorta morphology on aortic hemodynamics in patients possessing ascending thoracic aortic aneurysm (ATAA). The 3D blood flow velocities and geometry of the aorta were obtained by 4D flow MRI in 2 patients having ATAA. The results show that the WSS are very low near the anterior region of t...

Even if cardiovascular magnetic resonance (CMR) perfusion imaging has proven its relevance for visual detection of ischemia, myocardial blood flow (MBF) quantification at the voxel observation scale remains challenging. Integration of an automated segmentation step, prior to perfusion index estimation, might be a significant reconstruction componen...

Level of Evidence: 5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:319–320.

Objectives: The aim of this study was to investigate the feasibility of measuring the effects of a 14-day Periodic Fasting (PF) intervention (<200 cal) on multi-organs of primary interest (liver, visceral/subcutaneous/bone marrow fat, muscle) using non-invasive advanced magnetic resonance spectroscopic (MRS) and imaging (MRI) methods. Methods: One...

Purpose. It has been reported clinically that rupture or dissections in thoracic aortic aneurysms (TAA) often occur due to hypertension which may be modelled with sudden increase of peripheral resistance, inducing acute changes of blood volumes in the aorta. There is clinical evidence that more compliant aneurysms are less prone to rupture as they...

Diffusion tensor imaging (DTI) is a non-invasive technique used to obtain the three-dimensional fiber structure of whole human hearts, for both in vivo and ex vivo cases. However, by essence, DTI does not measure directly the orientations of myocardial fibers. In contrast, polarized light imaging (PLI) allows for physical measurements of fiber orie...

Purpose It has been reported clinically that rupture or dissections in thoracic aortic aneurysms (TAA) often occur due to hypertension which may be modelled with sudden increase of peripheral resistance, inducing acute changes of blood volumes in the aorta. There is clinical evidence that more compliant aneurysms are less prone to rupture as they c...

We report a patient-specific case of bicuspid aortic valve with fusion of right and left coronary leaflets (R-L type I BAV), moderate aortic valve deficiency and ascending thoracic aortic aneurysms (ATAA) who was treated by only ascending aorta replacement preserving the BAV. The flow eccentricity, the helicity intensity (h2), the circumferential t...

A novel ultrasound (US) high-channels platform is a pre-requisite to open new frontiers in diagnostic and/or therapy by experimental implementation of innovative advanced US techniques. To date, a few systems with more than 1000 transducers permit full and simultaneous control in both transmission and receiving of all single elements of arrays. A p...

Assessment of myocardial damage is important to obtain an accurate prognosis after myocardial infarction. Myocardial strains have been shown to be good indicators of the myocardial viability. Strain analysis has been used to identify dysfunctional regions, and several strain-based parameters have been proposed to detect regions of infarct. In this...

Cardiovascular diseases and myocardium infarction are main causes of death worldwide. After acute myocardium infarction, remodeling occurs within weeks resulting from a loss of cardiomyocytes in the damaged myocardium, and subsequent changes with regional tissue organization. Imaging methods able to render the local tissue directivity would be usef...

We present a comprehensive and original framework for the biomechanical analysis of patients affected by ascending thoracic aorta aneurysm and aortic insufficiency. Our aim is to obtain crucial indications about the role played by deranged hemodynamics on the ATAAs risk of rupture. Computational fluid dynamics analysis was performed using patient-s...

Background While a moderate exercise benefits on the cardiovascular system, consequences of a supraphysiological effort are not yet clear. Objective The aim of our study was to evaluate the consequences of an ultra-marathon on cardiac and muscles markers (CK, myoglobin, hsTnT, NT-proBNP, copeptin, H-FABP) but also markers of inflammation CRP DFO,...

Background: Pioneer studies demonstrate the impact of extreme sport load on the human brain, leading to threatening conditions for athlete's health such as cerebral edema. The investigation of brain water diffusivity, allowing the measurement of the intercellular water and the assessment of cerebral edema, can give a great contribution to the inves...

The MERMAIDS Project aims at mitigating the impact of microplastics caused by textile washing processes. Fibers discharged from washing synthetic cloths are a major contributor of the plastic soup. Microplastics concentrate persistent organic pollutants that can be ingested by marine biota, introducing toxic pollutants to the food chain.

[This corrects the article DOI: 10.1371/journal.pone.0161855.].

Fifteen patients with intradural spinal lesions were examined with an optimized dynamic contrast-enhanced MR perfusion sequence at 1.5T and 3T. SNR and mean contrast-to-noise ratio were better on 3T compared with 1.5T (P ≤ .05). The goodness of fit of the Tofts and Tofts extended pharmacokinetic models was similar between 1.5T and 3T. Thus, dynamic...

Ultrafast ultrasound imaging has become an intensive area of research thanks to its capability in reaching high frame rates. In this paper, we propose a scheme which allows the extension of the current Fourier-based techniques derived for planar acquisition to the reconstruction of sectorial scan with wide angle using diverging waves. The flexibili...

In sports medicine, there is increasing interest in quantifying the elastic properties of skeletal muscle, especially during extreme muscular stimulation, to improve our understanding of the impact of alterations in skeletal muscle stiffness on resulting pain or injuries, as well as the mechanisms underlying the relationships between these paramete...

Cardiac motion presents a major challenge in diffusion weighted MRI, often leading to large signal dropouts that necessitate repeated measurements. The diffusion process in the myocardium is difficult to investigate because of the unqualified sensitivity of diffusion measurements to 20 cardiac motion and in particular to myocardial strain. Using th...

Purpose In this study, we proposed an efficient free‐breathing strategy for rapid and improved cardiac diffusion‐weighted imaging (DWI) acquisition using a single‐shot spin‐echo echo planar imaging (SE‐EPI) sequence. Methods : A real‐time slice‐following technique during free‐breathing was combined with a sliding acquisition‐window strategy prior P...

Background: Delayed stent implantation after restoration of normal epicardial flow by a minimalist immediate mechanical intervention aims to decrease the rate of distal embolization and impaired myocardial reperfusion after percutaneous coronary intervention. We sought to confirm whether a delayed stenting (DS) approach (24-48 hours) improves myoc...

Ultrasound image reconstruction from the echoes received by an ultrasound probe after the transmission of diverging waves is an active area of research because of its capacity to insonify at ultra-high frame rate with large regions of interest using small phased arrays as the ones used in echocardiography. Current state-of-the-art techniques are ba...