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2. Influence of Morphometric and Mechanical Factors in Thoracic Aorta Finite Element Modeling

Author

Zhang, Ruifen, Sigovan, Monica, Clarysse, Patrick, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Woeginger, Gerhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Puyol Antón, Esther, editor, Pop, Mihaela, editor, Martín-Isla, Carlos, editor, Sermesant, Maxime, editor, Suinesiaputra, Avan, editor, Camara, Oscar, editor, Lekadir, Karim, editor, and Young, Alistair, editor

Published
2022
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3. Simultaneous assessment of microcalcifications and morphological criteria of vulnerability in carotid artery plaque using hybrid 18F-NaF PET/MRI

Author

Mechtouff, Laura, Sigovan, Monica, Douek, Philippe, Costes, Nicolas, Le Bars, Didier, Mansuy, Adeline, Haesebaert, Julie, Bani-Sadr, Alexandre, Tordo, Jérémie, Feugier, Patrick, Millon, Antoine, Luong, Stéphane, Si-Mohamed, Salim, Collet-Benzaquen, Diane, Canet-Soulas, Emmanuelle, Bochaton, Thomas, Crola Da Silva, Claire, Paccalet, Alexandre, Magne, David, Berthezene, Yves, and Nighoghossian, Norbert

Published
2022
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5. Reconstruction of blood flow velocity with deep learning information fusion from spectral ct projections and vessel geometry.

Author

Huang, Shusong, Sigovan, Monica, and Sixou, Bruno

Subjects
*FLOW velocity, *BLOOD flow, *UNSTEADY flow, *INVERSE problems, *HEMODYNAMICS, *DEEP learning
Abstract

AbstractIn this work, we investigate a new deep learning reconstruction method of blood flow velocity within deformed vessels from contrast enhanced X-ray projections and vessel geometry. The principle of the method is to perform linear or nonlinear dimension reductions on the Radon projections and on the mesh of the vessel. These low dimensional projections are then fused to obtain the velocity field in the vessel. The accuracy of the reconstruction method is proved using various neural network architectures with realistic unsteady blood flows. The approach leverages the vessel geometry information and outperforms the simple PCA-net. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Extended 3D approach for quantification of abnormal ascending aortic flow

Author

Sigovan, Monica, Dyverfeldt, Petter, Wrenn, Jarrett, Tseng, Elaine E, Saloner, David, and Hope, Michael D

Subjects
Biomedical and Clinical Sciences, Cardiovascular Medicine and Haematology, Clinical Sciences, Clinical Research, Cardiovascular, Heart Disease, Adult, Aged, Aorta, Aortic Valve, Aortic Valve Stenosis, Bicuspid Aortic Valve Disease, Blood Flow Velocity, Female, Heart Defects, Congenital, Heart Valve Diseases, Humans, Imaging, Three-Dimensional, Magnetic Resonance Imaging, Male, Middle Aged, MRI, Valves, BAV, Eccentric jets, Biomedical Engineering, Cognitive Sciences, Nuclear Medicine & Medical Imaging, Clinical sciences
Abstract

BackgroundFlow displacement quantifies eccentric flow, a potential risk factor for aneurysms in the ascending aorta, but only at a single anatomic location. The aim of this study is to extend flow displacement analysis to 3D in patients with aortic and aortic valve pathologies.Methods43 individuals were studied with 4DFlow MRI in 6 groups: healthy, tricuspid aortic valve (TAV) with aortic stenosis (AS) but no dilatation, TAV with dilatation but no AS, and TAV with both AS and dilatation, BAV without AS or dilatation, BAV without AS but with dilation. The protocol was approved by our institutional review board, and informed consent was obtained. Flow displacement was calculated for multiple planes along the ascending aorta, and 2D and 3D analyses were compared.ResultsGood correlation was found between 2D flow displacement and both maximum and average 3D values (r>0.8). Healthy controls had significantly lower flow displacement values with all approaches (p

Published
2015

8. Ferumoxytol-enhanced magnetic resonance angiography is a feasible method for the clinical evaluation of lower extremity arterial disease.

Author

Walker, Joy P, Nosova, Emily, Sigovan, Monica, Rapp, Joseph, Grenon, Marlene S, Owens, Christopher D, Gasper, Warren J, and Saloner, David A

Subjects
Lower Extremity, Kidney, Humans, Gadolinium DTPA, Contrast Media, Magnetic Resonance Angiography, Glomerular Filtration Rate, Risk Factors, Prospective Studies, Feasibility Studies, Pilot Projects, Predictive Value of Tests, Aged, Middle Aged, San Francisco, Male, Renal Insufficiency, Ferrosoferric Oxide, Peripheral Arterial Disease, Cardiovascular, Biomedical Imaging, Patient Safety, Clinical Research, Kidney Disease, 4.2 Evaluation of markers and technologies, 4.1 Discovery and preclinical testing of markers and technologies, Detection, screening and diagnosis, Clinical Sciences, Cardiovascular System & Hematology
Abstract

BackgroundRenal toxicity from conventional, iodinated, intravenous contrast agents is a common complication in patients with peripheral artery disease (PAD). Similarly, the potential for serious side effects prevents the use of gadolinium-based agents in many patients with depressed renal function. Ferumoxytol-enhanced magnetic resonance angiography (Fe-MRA) is a novel technique that uses an intravenous, ultrasmall, superparamagnetic, iron oxide preparation, currently approved by the Food and Drug Administration for the treatment of iron deficiency anemia in adults with chronic kidney disease. Our objective was to determine the feasibility of Fe-MRA for clinical decision making in PAD patients.MethodsThis was a prospective pilot study assessing 10 patients with suspected arterial occlusive disease with contrast-enhanced MRA of the aorta and lower extremities. Of those, 5 had renal insufficiency and were imaged with Fe-MRA, whereas the remainder underwent gadolinium-enhanced MRA. Qualitative and quantitative evaluations of deidentified images at each arterial station were independently performed by 4 blinded vascular surgeons.ResultsAll patients were men, with an average age of 68 ± 4 years. The 2 groups had similar incidences of diabetes, hypertension, hyperlipidemia, and coronary artery disease. Patients undergoing Fe-MRA had significantly decreased renal function (estimated glomerular filtration rate, 35.4 vs. 77.6; P = 0.02). There were no adverse events during contrast administration in either group. No difference was found in the overall quality of the ferumoxytol versus the gadolinium studies (7.1 ± 2.0 vs. 7.4 ± 2.4, P = 0.67). Similarly, reviewers felt comfortable basing clinical decisions on the images 89% of the time with both the ferumoxytol and gadolinium groups (P = 1.00).ConclusionsThis is the first report of an important alternative to conventional computed tomography angiography and MRA in PAD patients, particularly in the setting of renal insufficiency. Fe-MRA provides a useful tool in patients with suspected lower extremity PAD without the potential risks of gadolinium.

Published
2015

9. MRI hemodynamic markers of progressive bicuspid aortic valve-related aortic disease.

Author

Hope, Michael D, Sigovan, Monica, Wrenn, S Jarrett, Saloner, David, and Dyverfeldt, Petter

Subjects
Aortic Valve, Humans, Heart Valve Diseases, Disease Progression, Observer Variation, Imaging, Three-Dimensional, Magnetic Resonance Angiography, Magnetic Resonance Imaging, Cine, Blood Flow Velocity, Sensitivity and Specificity, Reproducibility of Results, Adult, Female, Male, Young Adult, Biomarkers, Bicuspid Aortic Valve Disease, BAV, MRI, aorta, eccentric jets, valves, Pediatric, Clinical Research, Cardiovascular, Biomedical Imaging, Congenital Structural Anomalies, 4.2 Evaluation of markers and technologies, Detection, screening and diagnosis, Physical Sciences, Engineering, Medical and Health Sciences, Nuclear Medicine & Medical Imaging
Abstract

PurposeTo determine the reproducibility of MRI aortic hemodynamic markers and to assess their relationship to aortic growth in a cohort of patients with bicuspid aortic valves (BAV).Materials and methodsTwenty-five patients previously studied with four-dimensional (4D) Flow imaging who had at least two separate cross-sectional imaging studies to assess for aortic growth were included: tricuspid aortic valve (TAV) controls without valvular disease (n = 12) and patients with BAV (n = 13). Flow data from the ascending aorta was used for calculation of peak velocity, normalized flow displacement, maximum wall shear stress (WSS), mean WSS, and minimal WSS. Pearson's correlation was used to evaluate interobserver agreement, and linear regression to evaluate the correlation between the different hemodynamic markers and growth. Patient informed consent was waived by the institutional review board that approved the study.ResultsPeak velocity and flow displacement were very reproducible (r = 0.90-1.0 and r = 0.91-0.98, respectively). The range of WSS parameters was largely reproducible (0.47 < r < 0.96) with the greatest variability at the data extraction stage of analysis (0.47 < r < 0.85). Flow displacement best correlated with interval aortic growth (r = 0.65), peak velocity was moderately correlated (r = 0.35), but the WSS parameters did not correlate well with growth (r < 0.17).ConclusionFlow displacement is a simple and reproducible hemodynamic marker that shows good correlation with aortic growth in patients with bicuspid aortic valves.

Published
2014

10. Vascular Remodeling in Autogenous Arterio-Venous Fistulas by MRI and CFD

Author

Sigovan, Monica, Rayz, Vitaliy, Gasper, Warren, Alley, Hugh F, Owens, Christopher D, and Saloner, David

Subjects
Fluid Mechanics and Thermal Engineering, Engineering, Biomedical Engineering, Biomedical Imaging, Bioengineering, Clinical Research, Kidney Disease, Aged, Aged, 80 and over, Arm, Arteriovenous Shunt, Surgical, Hemodynamics, Humans, Hydrodynamics, Imaging, Three-Dimensional, Magnetic Resonance Angiography, Male, Middle Aged, Postoperative Complications, Renal Dialysis, Computational fluid dynamics, Magnetic resonance imaging, Vascular access, Hemodialysis fistula, Vascular remodeling, WSS
Abstract

Hemodynamic parameters play an important role in regulating vascular remodeling in arterio-venous fistula (AVF) maturation. Investigating the changes in hemodynamic parameters during AVF maturation is expected to improve our understanding of fistula failure, but very little data on actual temporal changes in human AVFs is available. The present study aimed to assess the feasibility of using a noncontrast-enhanced MRI protocol combined with CFD modeling to relate hemodynamic changes to vascular remodeling following native AVF placement. MR angiography (MRA) and MR velocimetry (MRV) data was acquired peri-operatively, 1 month, and 3 months later in three patients. Vascular geometries were obtained by segmentation of the MRA images. Pulsatile flow simulations were performed in the patient specific vascular geometries with time-dependent boundary conditions prescribed from MRV measurements. A principal result of the study is the description of WSS changes over time in the same patients. The disturbed flow observed in the venous segments resulted in a variability of the WSS distribution and could be responsible for the non-uniform remodeling of the vessel. The artery did not show regions of disturbed flow upstream from the anastomosis, which would be consistent with the uniform remodeling. MRI use demonstrated the ability to provide a comprehensive evaluation of clinically relevant information for the investigation of upper extremity AVFs. 3D geometry from MRA in combination with MRV provides the opportunity to perform detailed CFD analysis of local hemodynamics in order to determine flow descriptors affecting fistula maturation.

Published
2013

12. A proposal of risk indicators for pathological development from hemodynamic simulation: application to aortic dissection

Author

Pan Wenyang, Kulisa Pascale, Bou-Saïd Benyebka, El Hajem Mahmoud, Simoëns Serge, and Sigovan Monica

Subjects
Pharmaceutical Science
Abstract

Cardiovascular diseases are the leading cause of mortality in the industrialized world. Among these diseases, aortic dissection affects the aorta wall and is a surgical emergency with a low survival rate. This pathology occurs when an injury leads to a localized tear of the innermost layer of the aorta. It allows blood to flow between the layers of the aortic wall, forcing the layers apart and creating a false lumen. Endovascular treatment seeks to obliterate the entrances to the false lumen with a covered stent. There are very few studies on the postoperative demonstration of blood flow phenomena in the aortic dissection endovascular treatment. It is crucial to study the hemodynamics of blood in the aorta after an intervention because the new geometrical configuration of the aorta with a stent leads to modifications in blood flow. For the surgeons, the procedure can only be performed empirically, using MRI-4D images to view the postoperative flow of the patient’s blood in the aorta with the stent. This paper aims to present a numerical tool developed from the open-source software FOAM- Extend®, allowing for multiphysics numerical simulations. Using MRI data, a bio-faithful model of the patient-specific case was built. Numerical simulations were performed to predict preoperative and postoperative (endovascular treatment) hemodynamics. The modifications of the flow in the aorta were analyzed focusing on the postoperative perfusions. The results were compared with the corresponding MRI data and have a good qualitative agreement. Biomarkers are calculated to localize possible zones of post-operative pathological developments and recommendations may be suggested to the surgeons.

Published
2023
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13. USPIO-enhanced MR Angiography of Arteriovenous Fistulas in Patients with Renal Failure

Author

Sigovan, Monica, Gasper, Warren, Alley, Hugh F, Owens, Christopher D, and Saloner, David

Subjects
Biomedical and Clinical Sciences, Clinical Sciences, Clinical Research, Biomedical Imaging, Kidney Disease, Anastomosis, Surgical, Arteriovenous Anastomosis, Contrast Media, Dextrans, Female, Humans, Image Enhancement, Magnetic Resonance Angiography, Magnetite Nanoparticles, Male, Renal Insufficiency, Reproducibility of Results, Sensitivity and Specificity, Medical and Health Sciences, Nuclear Medicine & Medical Imaging, Clinical sciences
Abstract

PurposeTo determine the feasibility of using ferumoxytol-enhanced magnetic resonance (MR) angiography to depict the vasculature of hemodialysis fistulas and improve image quality compared with nonenhanced time-of-flight (TOF) MR angiography.Materials and methodsThe study was institutional review board approved and was in compliance with HIPAA regulations. All participants provided written informed consent. TOF and first-pass ferumoxytol-enhanced MR angiography were performed in 10 patients with upper extremity autogenous fistulas. Ferumoxytol was administered as a bolus solution containing 430 μmol of elemental iron. A qualitative comparison was performed on maximum intensity projection images. Lumen depiction was evaluated by using a five-point scale. The uniformity of intraluminal signal intensity was measured as the ratio between the mean signal intensity of the entirety of the imaged fistula and its standard deviation. The contrast-to-noise ratio (CNR) between intraluminal signal and adjacent tissue was evaluated as a function of image acquisition time. Lumen depiction scores, luminal signal heterogeneity, and CNR efficiency were compared between TOF and ferumoxytol-enhanced MR angiography by using a Wilcoxon-Mann-Whitney test.ResultsFlow artifacts were greatly reduced by the use of ferumoxytol-enhanced MR angiography. Ferumoxytol-enhanced MR angiography had significantly better performance than TOF MR angiography as measured with the following: lumen depiction scores in all segments (mean, 4.7±0.1 [standard error of the mean]; vs 3.0±0.3 for arterial inflow, 4.1±0.3 vs 1.9±0.3 for arterial outflow, 3.7±0.3 vs 1.8±0.2 for anastomosis, and 4.5±0.2 vs 2.1±0.2 for venous outflow; P

Published
2012

20. Hemodynamic Changes Before and After Endovascular Treatment of Type B Aortic Dissection by 4D Flow MRI

Author

Cosset, Benoit, Boussel, Loic, Davila Serrano, Eduardo, Millon, Antoine, Douek, Philippe, Farhat, Fadi, Sigovan, Monica, Boussel, Loic, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Hospices Civils de Lyon (HCL), Modeling & analysis for medical imaging and Diagnosis (MYRIAD), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL)

Subjects
Helical Flow, [SDV.IB.IMA] Life Sciences [q-bio]/Bioengineering/Imaging, [SDV.MHEP.CHI] Life Sciences [q-bio]/Human health and pathology/Surgery, [SDV.MHEP.CSC]Life Sciences [q-bio]/Human health and pathology/Cardiology and cardiovascular system, [SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, Parametric Hemodynamic Maps, [SDV.MHEP.CHI]Life Sciences [q-bio]/Human health and pathology/Surgery, Hemodynamic Evaluation, 4D phase-contrast MRI, Cardiology and Cardiovascular Medicine, Thoracic Endovascular Aortic Repair, Type B Aortic Dissection, [SDV.MHEP.CSC] Life Sciences [q-bio]/Human health and pathology/Cardiology and cardiovascular system
Abstract

Objective:The standard treatment for complicated Stanford type B aortic dissection (TBAD) is thoracic endovascular aortic repair (TEVAR). Functional parameters, specifically blood flow, are not measured in the clinical assessment of TEVAR, yet they are of outmost importance in patient outcome. Consequently, we investigated the impact of TEVAR on the flows in the aorta and its branches in TBAD using 4D Phase-Contrast Magnetic Resonance Imaging (4D Flow MRI).MethodsSeven patients with TBAD scheduled for TEVAR underwent pre and post-operative 4D Flow MRI. An experienced reader assessed the presence of helical flow in the false lumen (FL) using streamlines and measured net flow at specific locations. In addition, forward and reverse flows, stasis, helicity, and absolute helicity were computed automatically along the aorta centerline. Average values were then computed in the segmented vessels. Impact of TEVAR on these parameters was assessed with a Wilcoxon signed rank test. Impact of the metallic stent on the velocity quantification was assessed using intra-class correlation coefficient (ICC) between velocities measured intra-stent and in adjacent stent-free regions.ResultsFL helical flow was observed proximally in 6 cases and distally in 2 cases pre-operatively. Helical flow disappeared post-TEVAR proximally, but developed distally for 2 patients. Intra-stent measures were similar to stent-free with a median difference of 0.1 L/min and an ICC equal to 0.967 (p < 0.01). Forward flow increased from 59.9 to 81.6% in the TL and significantly decreased in the FL from 15.9 to 3.3%. Similarly, reverse flow increased in the TL from 4.36 to 10.8% and decreased in the FL from 10.3 to 4.6%. No significant changes were observed in net flow for aortic branches (p > 0.05). A significant increase in FL stasis was observed (p = 0.04).DiscussionTEVAR significantly increased forward flow in the TL and significantly decreased both forward and reverse flows in the FL. Interestingly, reverse flow in the TL increased post-TEVAR, which could be due to increased rigidity of the wall, due to the metallic stent. User independent helicity quantification enabled detection of elevated helicity at the level of secondary entry tears which had been missed by streamline visualization.

Published
2022
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21. In Vivo Molecular K-Edge Imaging of Atherosclerotic Plaque Using Photon-counting CT

Author

Si-Mohamed, Salim A., Sigovan, Monica, Hsu, Jessica C., Tatard-Leitman, Valérie, Chalabreysse, Lara, Naha, Pratap C., Garrivier, Thibaut, Dessouky, Riham, Carnaru, Miruna, Boussel, Loic, Cormode, David P., Douek, Philippe C., Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Modeling & analysis for medical imaging and Diagnosis (MYRIAD), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Sigovan, Monica

Subjects
[INFO.INFO-IM] Computer Science [cs]/Medical Imaging, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021
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22. Velocity-based cardiac self-gating in free-running radial 4D Flow MRI

Author

Sigovan, Monica, Duchateau, N, Douek, Philippe, Prieto, C, Boussel, L., Sigovan, Monica, Modeling & analysis for medical imaging and Diagnosis (MYRIAD), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Hospices Civils de Lyon (HCL), and King‘s College London

Subjects
[SDV.IB.IMA] Life Sciences [q-bio]/Bioengineering/Imaging, [SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging
Abstract

International audience; Introduction: Free-running whole-heart acquisitions with the capability of deriving cardiac self-gating (SG) signals present clear interest, particularly at 3T, where the ECG signal suffers from the magnetohydrodynamic effect and acquisition related noise. Our goal was to develop a novel velocity-based cardiac SG strategy for free-running radial 4D Flow imaging and to investigate the impact of cardiac SG on the velocity quantification in the thoracic aorta. Methods: We implemented a free-running interleaved (8 spokes/interleaf) 3D radial velocity mapping sequence on a 1.5T Philips Ingenia (Philips, Best, The Netherlands), based on a spiral phyllotaxis pattern [1]. Imaging was performed on the thorax of 5 healthy subjects as follows: TE/TR 2.5/6 ms, FA=6•, VENC=180-240 cm/s, 2.5 mm isotropic voxel, acquisition time: 8-12 minutes. First, a sliding-window reconstruction using 64 consecutive spokes and a step of 8 spokes yielded high temporal and low spatial resolution velocity resolved volumes. The average speed in the aorta was obtained for each volume, using a mask drawn on the fully sampled reconstruction. Then, to obtain the cardiac SG signal, the temporal evolution of the aorta average speed was filtered in the frequency domain and interpolated using multiscale kernel ridge regression [2]. Finally, the cardiac SG signal and the ECG were used to bin the data in the same number of cardiac phases (N=12-18). Cardiac and velocity resolved images were then reconstructed offline using a compressed sensing algorithm implemented in Matlab (The Mathworks, Inc, Natick, MA). Velocity measurements in the thoracic aorta were then compared between SG and ECG based gating. Results: A comparison of the frequency analysis of the temporal evolution of the aorta speed and the ECG signal is presented in Figure A for a representative case. The frequency peak corresponding to the heart rate and the first harmonic can be observed at the same location. Despite similar average RR intervals between SG and ECG, the R-peak detection precision for SG was 50ms on average. Velocity quantification showed underestimation of peak systolic values for SG compared to ECG (Figure B). In order to confirm that the underestimation is due to the R-peak detection precision, we simulated 1% and 5% variability in the R-peak location in the ECG signal by random sampling according to a uniform distribution and used this simulated signal for cardiac binning. Similar to SG, an underestimation can be observed for the same case in the average speed (Figure C). Discussion: We present here a novel approach to cardiac SG specifically dedicated to 4D Flow MRI. Our results are in agreement with previously reported results using a navigator spoke based method for cardiac SG in 3D radial [3]. While this precision does not affect the resulting anatomical images, we have shown an impact on the velocity quantification, particularly an underestimation of the peak systolic values. This underestimation was described previously for 3D radial 4D Flow [1], however its source was not completely identified. Improvement of the precision in the R-peak detection is expected with the use of more advanced methods in the sliding window reconstruction. In addition, a respiratory SG signal can be obtained in absolute values and enable respiratory motion correction (not shown). This is an advantage of our method, compared to other previous fully self-gated strategies.

Published
2021

25. First In-Human Results of Computed Tomography Angiography for Coronary Stent Assessment With a Spectral Photon Counting Computed Tomography

Author

Boccalini, Sara, primary, Si-Mohamed, Salim A., additional, Lacombe, Hugo, additional, Diaw, Adja, additional, Varasteh, Mohammad, additional, Rodesch, Pierre-Antoine, additional, Villien, Marjorie, additional, Sigovan, Monica, additional, Dessouky, Riham, additional, Coulon, Philippe, additional, Yagil, Yoad, additional, Lahoud, Elias, additional, Erhard, Klaus, additional, Rioufol, Gilles, additional, Finet, Gerard, additional, Bonnefoy-Cudraz, Eric, additional, Bergerot, Cyrille, additional, Boussel, Loic, additional, and Douek, Philippe C., additional

Published
2021
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30. What's Behind a '+” Sign? Perceiving an Arithmetic Operator Recruits Brain Circuits for Spatial Orienting

Author

Mathieu, Romain, Epinat-Duclos, Justine, Sigovan, Monica, Breton, Audrey, Cheylus, Anne, Fayol, Michel, Thevenot, Catherine, Prado, Jérôme, Mathieu, Romain, Epinat-Duclos, Justine, Sigovan, Monica, Breton, Audrey, Cheylus, Anne, Fayol, Michel, Thevenot, Catherine, and Prado, Jérôme

Abstract

Do mathematical symbols evoke spatial representations? Although behavioral studies have long demonstrated interactions between space and the processing of Arabic digits, how to interpret these results remains controversial. Here, we tested whether activity in regions supporting spatial processing contributes to the processing of symbols conveying fundamental arithmetic concepts—such as operation signs—even in the absence of associated digits. Using functional magnetic resonance imaging, we show that merely perceiving a "+” sign triggers activity in brain regions that support the orienting of spatial attention in adults. Activity in these regions was greater for "+” than for "×” signs, indicating that it is modulated by whether an operator reflects an operation that evokes numerical manipulation (rather than rote memorization). Finally, the degree to which subjects activated a spatial region in response to a "+” sign was correlated with the degree to which subjects benefited from being briefly presented with that sign before having to calculate a single-digit addition problem, an effect termed operator-priming. Therefore, not only are some arithmetic operators linked to spatial intuitions, but such intuitions might also have an important role during arithmetic calculation. More generally, our findings support the view that mathematical symbols inherently evoke spatial representations.

Published
2021

31. Simultaneous assessment of microcalcifications and morphological criteria of vulnerability in carotid artery plaque using hybrid 18F-NaF PET/MRI.

Author

Mechtouff, Laura, Sigovan, Monica, Douek, Philippe, Costes, Nicolas, Le Bars, Didier, Mansuy, Adeline, Haesebaert, Julie, Bani-Sadr, Alexandre, Tordo, Jérémie, Feugier, Patrick, Millon, Antoine, Luong, Stéphane, Si-Mohamed, Salim, Collet-Benzaquen, Diane, Canet-Soulas, Emmanuelle, Bochaton, Thomas, Crola Da Silva, Claire, Paccalet, Alexandre, Magne, David, and Berthezene, Yves

Abstract

Background: Previous studies have suggested the role of microcalcifications in plaque vulnerability. This exploratory study sought to assess the potential of hybrid positron-emission tomography (PET)/magnetic resonance imaging (MRI) using 18F-sodium fluoride (18F-NaF) to check simultaneously 18F-NaF uptake, a marker of microcalcifications, and morphological criteria of vulnerability. Methods and results: We included 12 patients with either recently symptomatic or asymptomatic carotid stenosis. All patients underwent 18F-NaF PET/MRI. 18F-NaF target-to-background ratio (TBR) was measured in culprit and nonculprit (including contralateral plaques of symptomatic patients) plaques as well as in other arterial walls. Morphological criteria of vulnerability were assessed on MRI. Mineral metabolism markers were also collected. 18F-NaF uptake was higher in culprit compared to nonculprit plaques (median TBR 2.6 [2.2-2.8] vs 1.7 [1.3-2.2]; P = 0.03) but was not associated with morphological criteria of vulnerability on MRI. We found a positive correlation between 18F-NaF uptake and calcium plaque volume and ratio but not with circulating tissue-nonspecific alkaline phosphatase (TNAP) activity and inorganic pyrophosphate (PPi) levels. 18F-NaF uptake in the other arterial walls did not differ between symptomatic and asymptomatic patients. Conclusions: 18F-NaF PET/MRI may be a promising tool for providing additional insights into the plaque vulnerability. [ABSTRACT FROM AUTHOR]

Published
2022
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32. Response

Author

Hope, Michael D., Sigovan, Monica, Dyverfeldt, Petter, and Saloner, David

Published
2012
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35. Simultaneous assessment of microcalcifications and morphological criteria of vulnerability in carotid artery plaque using hybrid 18F-NaF PET/MRI

Author

Mechtouff, Laura, primary, Sigovan, Monica, additional, Douek, Philippe, additional, Costes, Nicolas, additional, Le Bars, Didier, additional, Mansuy, Adeline, additional, Haesebaert, Julie, additional, Bani-Sadr, Alexandre, additional, Tordo, Jérémie, additional, Feugier, Patrick, additional, Millon, Antoine, additional, Luong, Stéphane, additional, Si-Mohamed, Salim, additional, Collet-Benzaquen, Diane, additional, Canet-Soulas, Emmanuelle, additional, Bochaton, Thomas, additional, Crola Da Silva, Claire, additional, Paccalet, Alexandre, additional, Magne, David, additional, Berthezene, Yves, additional, and Nighoghossian, Norbert, additional

Published
2020
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37. First In-Human Results of Computed Tomography Angiography for Coronary Stent Assessment With a Spectral Photon Counting Computed Tomography.

Author

Boccalini, Sara, Si-Mohamed, Salim A., Lacombe, Hugo, Diaw, Adja, Varasteh, Mohammad, Rodesch, Pierre-Antoine, Villien, Marjorie, Sigovan, Monica, Dessouky, Riham, Coulon, Philippe, Yagil, Yoad, Lahoud, Elias, Erhard, Klaus, Rioufol, Gilles, Finet, Gerard, Bonnefoy-Cudraz, Eric, Bergerot, Cyrille, Boussel, Loic, and Douek, Philippe C.

Published
2022
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40. Feasibility of improving vascular imaging in the presence of metallic stents using spectral photon counting CT and K-edge imaging

Author

Sigovan, Monica, primary, Si-Mohamed, Salim, additional, Bar-Ness, Daniel, additional, Mitchell, Julia, additional, Langlois, Jean-Baptiste, additional, Coulon, Philippe, additional, Roessl, Ewald, additional, Blevis, Ira, additional, Rokni, Michal, additional, Rioufol, Gilles, additional, Douek, Philippe, additional, and Boussel, Loic, additional

Published
2019
Full Text
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41. Non-invasive evaluation coronary artery stenosis: in-vitro comparison of a Spectral Photon Counting CT and a Spectral Dual Layer CT

Author

Sigovan, Monica, Coulon, P, Si Mohamed, S, Bar-Ness, D, Vlassenbroek, A, Hamersvelt, R, Leiner, T, Boussel, L, Douek, P, Imagerie et modélisation Vasculaires, Thoraciques et Cérébrales (MOTIVATE), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2017

42. Non-invasive Evaluation of Soft-Plaque-Restenosis in Coronary Artery Stents: Initial In-vitro Comparison of a Spectral Photon Counting CT and a Spectral Dual Layer CT System

Author

T, Hickethier, D, Bar-Ness, AC, Bunck, D, Maintz, G, Pahn, P, Coulon, Salim, Si-Mohamed, Philippe, Douek, Sigovan, Monica, Imagerie et modélisation Vasculaires, Thoraciques et Cérébrales (MOTIVATE), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2017

43. Multicolor spectral photon-counting computed tomography: in vivo dual contrast imaging with a high count rate scanner

Author

Cormode, David P., Si-Mohamed, Salim, Bar-Ness, Daniel, Sigovan, Monica, Naha, Pratap C., Balegamire, Joelle, Lavenne, Franck, Coulon, Philippe, Roessl, Ewald, Bartels, Matthias, Rokni, Michal, Blevis, Ira, Boussel, Loic, Douek, Philippe, Centre Hospitalier Universitaire de Nîmes (CHU Nîmes), Imagerie et modélisation Vasculaires, Thoraciques et Cérébrales (MOTIVATE), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etude et de Recherche Multimodal Et Pluridisciplinaire en imagerie du vivant (CERMEP - imagerie du vivant), Université de Lyon-Université de Lyon-CHU Grenoble-Hospices Civils de Lyon (HCL)-CHU Saint-Etienne-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Philips Healthcare, Department of Radiology, Cardiological Hospital, and Hospices Civils de Lyon

Subjects
Calcium Phosphates, Male, Phantoms, Imaging, Science, Contrast Media, Metal Nanoparticles, Article, Iopamidol, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Medicine, Animals, Female, Gold, Rabbits, Tomography, X-Ray Computed
Abstract

International audience; A new prototype spectral photon-counting computed tomography (SPCCT) based on a modified clinical CT system has been developed. SPCCT analysis of the energy composition of the transmitted x-ray spectrum potentially allows simultaneous dual contrast agent imaging, however, this has not yet been demonstrated with such a system. We investigated the feasibility of using this system to distinguish gold nanoparticles (AuNP) and an iodinated contrast agent. The contrast agents and calcium phosphate were imaged in phantoms. Conventional CT, gold K-edge, iodine and water images were produced and demonstrated accurate discrimination and quantification of gold and iodine concentrations in a phantom containing mixtures of the contrast agents. In vivo experiments were performed using New Zealand White rabbits at several times points after injections of AuNP and iodinated contrast agents. We found that the contrast material maps clearly differentiated the distributions of gold and iodine in the tissues allowing quantification of the contrast agents' concentrations, which matched their expected pharmacokinetics. Furthermore, rapid, repetitive scanning was done, which allowed measurement of contrast agent kinetics with high temporal resolution. In conclusion, a clinical scale, high count rate SPCCT system is able to discriminate gold and iodine contrast media in different organs in vivo.

Published
2017
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44. Initial experience in improving stent analysis and intra stent lumen assessment using Spectral Photon Counting CT and K-edge imaging

Author

Sigovan, Monica, D, Bar-Ness, S, Si-Mohamed, J, Mitchell, JB, Langlois, P, Coulon, M, Bartels, B, Brendel, Heiner, Daerr, Axel, Thran, Ewald, Roessl, Ira, Blevis, M, Rokni, Philippe, Douek, Loic, Boussel, Imagerie et modélisation Vasculaires, Thoraciques et Cérébrales (MOTIVATE), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2016

49. Review of an initial experience with an experimental spectral photon-counting computed tomography system

Author

UCL - (SLuc) Service de radiologie, UCL - SSS/IREC/IMAG - Pôle d'imagerie médicale, Si-Mohamed, Salim, Bar-Ness, Daniel, Sigovan, Monica, Cormode, David P., Coulon, Philippe, Coche, Emmanuel, Vlassenbroek, Alain, Normand, Gabrielle, Boussel, Loic, Douek, Philippe, UCL - (SLuc) Service de radiologie, UCL - SSS/IREC/IMAG - Pôle d'imagerie médicale, Si-Mohamed, Salim, Bar-Ness, Daniel, Sigovan, Monica, Cormode, David P., Coulon, Philippe, Coche, Emmanuel, Vlassenbroek, Alain, Normand, Gabrielle, Boussel, Loic, and Douek, Philippe

Abstract

Spectral photon-counting CT (SPCCT) is an emerging X-ray imaging technology that extends the scope of available diagnostic imaging tools. The main advantage of photon-counting CT technology is better sampling of the spectral information from the transmitted spectrum in order to benefit from additional physical information being produced during matter interaction, including photo-electric and Compton effects, and the K-edge effect. The K-edge, which is specific for a given element, is the increase in X-ray absorption of the element above the binding energy between its inner electronic shell and the nucleus. Hence, the spectral information contributes to better characterization of tissues and materials of interest, explaining the excitement surrounding this area of X-ray imaging. Other improvements of SPCCT compared with conventional CT, such as higher spatial resolution, lower radiation exposure and lower noise are also expected to provide benefits for diagnostic imaging. In this review, we describe multi-energy CT imaging, from dual energy to photon counting technology, and our initial experience results using a clinical-scale spectral photon counting CT (SPCCT) prototype system in vitro and in vivo. In addition, possible clinical applications are introduced.

Published
2017

50. Gadolinium enhancement vs WSS and Oscillatory shear Index (OSI) in human carotid atherosclerosis by MRI and CFD: A preliminary Study

Author

Sigovan, Monica, Mael, Roy, Vitaliy, Rayz, Douek, Philippe, Boussel, Loic, Imagerie et modélisation Vasculaires, Thoraciques et Cérébrales (MOTIVATE), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2014

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