Benjamin Leporq
University of Lyon
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Publication
Featured researches published by Benjamin Leporq.
NMR in Biomedicine | 2014
Benjamin Leporq; Simon A. Lambert; Maxime Ronot; Valérie Vilgrain; Bernard E. Van Beers
The aim of this work was to validate a sequential method for quantifying the triglyceride fatty acid composition with 3.0 T MRI.
Journal of Magnetic Resonance Imaging | 2015
Benjamin Leporq; Hervé Saint-Jalmes; Cécile Rabrait; Frank Pilleul; Olivier Guillaud; Jérôme Dumortier; Jean-Yves Scoazec; Olivier Beuf
Optimization of multi b‐values MR protocol for fast intra‐voxel incoherent motion imaging of the liver at 3.0 Tesla.
Journal of Magnetic Resonance Imaging | 2012
Benjamin Leporq; Jérôme Dumortier; Frank Pilleul; Olivier Beuf
To evaluate a 1.5T magnetic resonance imaging (MRI) protocol, including a dedicated acquisition sequence and a postprocessing tool for the quantitative analysis of hepatic tissue perfusion. Estimated perfusion parameters and histological results based on the METAVIR classification were prospectively compared for hepatic fibrosis assessment.
Magnetic Resonance in Medicine | 2016
Benjamin Leporq; Simon A. Lambert; Maxime Ronot; Imane Boucenna; Pierre Colinart; François Cauchy; Valérie Vilgrain; Valérie Paradis; Bernard E. Van Beers
To develop an MRI method for quantifying hepatic fat content and visceral adipose tissue fatty acid composition in mice on a 7.0T preclinical system.
European Radiology | 2017
Céline Giraudeau; Benjamin Leporq; Sabrina Doblas; Matthieu Lagadec; Catherine M. Pastor; Jean-Luc Daire; Bernard E. Van Beers
ObjectivesChanges in the expression of hepatocyte membrane transporters in advanced fibrosis decrease the hepatic transport function of organic anions. The aim of our study was to assess if these changes can be evaluated with pharmacokinetic analysis of the hepatobiliary transport of the MR contrast agent gadoxetate.MethodsDynamic gadoxetate-enhanced MRI was performed in 17 rats with advanced fibrosis and 8 normal rats. After deconvolution, hepatocyte three-compartmental analysis was performed to calculate the hepatocyte influx, biliary efflux and sinusoidal backflux rates. The expression of Oatp1a1, Mrp2 and Mrp3 organic anion membrane transporters was assessed with reverse transcription polymerase chain reaction.ResultsIn the rats with advanced fibrosis, the influx and efflux rates of gadoxetate decreased and the backflux rate increased significantly (p = 0.003, 0.041 and 0.010, respectively). Significant correlations were found between influx and Oatp1a1 expression (r = 0.78, p < 0.001), biliary efflux and Mrp2 (r = 0.50, p = 0.016) and sinusoidal backflux and Mrp3 (r = 0.61, p = 0.002).ConclusionThese results show that changes in the bidirectional organic anion hepatocyte transport function in rats with advanced liver fibrosis can be assessed with compartmental analysis of gadoxetate-enhanced MRI.Key Points• Expression of hepatocyte transporters is modified in rats with advanced liver fibrosis.• Kinetic parameters at gadoxetate-enhanced MRI are correlated with hepatocyte transporter expression.• Hepatocyte transport function can be assessed with compartmental analysis of gadoxetate-enhanced MRI.• Compartmental analysis of gadoxetate-enhanced MRI might provide biomarkers in advanced liver fibrosis.
NMR in Biomedicine | 2017
Benjamin Leporq; Simon A. Lambert; Maxime Ronot; Valérie Vilgrain; B.E. Van Beers
Non‐alcoholic steatohepatitis (NASH) is characterized at histology by steatosis, hepatocyte ballooning and inflammatory infiltrates, with or without fibrosis. Although diamagnetic material in fibrosis and inflammation can be detected with quantitative susceptibility imaging, fatty acid composition changes in NASH relative to simple steatosis have also been reported. Therefore, our aim was to develop a single magnetic resonance (MR) acquisition and post‐processing scheme for the diagnosis of steatohepatitis by the simultaneous quantification of hepatic fat content, fatty acid composition, T2* transverse relaxation time and magnetic susceptibility in patients with non‐alcoholic fatty liver disease. MR acquisition was performed at 3.0 T using a three‐dimensional, multi‐echo, spoiled gradient echo sequence. Phase images were unwrapped to compute the B0 field inhomogeneity (ΔB0) map. The ΔB0‐demodulated real part images were used for fat–water separation, T2* and fatty acid composition quantification. The external and internal fields were separated with the projection onto dipole field method. Susceptibility maps were obtained after dipole inversion from the internal field map with single‐orientation Bayesian regularization including spatial priors. Method validation was performed in 32 patients with biopsy‐proven, non‐alcoholic fatty liver disease from which 12 had simple steatosis and 20 NASH. Liver fat fraction and T2* did not change significantly between patients with simple steatosis and NASH. In contrast, the saturated fatty acid fraction increased in patients with NASH relative to patients with simple steatosis (48 ± 2% versus 44 ± 4%; p < 0.05) and the magnetic susceptibility decreased (−0.30 ± 0.27 ppm versus 0.10 ± 0.14 ppm; p < 0.001). The area under the receiver operating characteristic curve for magnetic susceptibility as NASH marker was 0.91 (95% CI: 0.79–1.0). Simultaneous MR quantification of fat content, fatty acid composition, T2* and magnetic susceptibility is feasible in the liver. Our preliminary results suggest that quantitative susceptibility imaging has a high diagnostic performance for the diagnosis of NASH.
Clinical Science | 2018
Benjamin Leporq; Jean-Luc Daire; Catherine M. Pastor; Pierre Deltenre; Christine Sempoux; Sabine Schmidt; Bernard E. Van Beers
The purpose of the present study was to develop and perform initial validation of dynamic MRI enhanced with gadoxetic acid as hepatobiliary contrast agent to quantify hepatic perfusion and hepatocyte function in patients with chronic liver disease. Free-breathing, dynamic gadoxetic acid-enhanced MRI was performed at 3.0 T using a 3D time-resolved angiography sequence with stochastic trajectories during 38 min. A dual-input three-compartment model was developed to derive hepatic perfusion and hepatocyte function parameters. Method feasibility was assessed in 23 patients with biopsy-proven chronic liver disease. Parameter analysis could be performed in 21 patients (91%). The hepatocyte function parameters were more discriminant than the perfusion parameters to differentiate between patients with minimal fibrosis (METAVIR F0-F1), intermediate fibrosis (F2-F3) and cirrhosis (F4). The areas under the receiver operating characteristic curves (ROCs) to diagnose significant fibrosis (METAVIR F ≥ 2) were: 0.95 (95% CI: 0.87-1; P<0.001) for biliary efflux, 0.88 (95% CI: 0.73-1; P<0.01) for sinusoidal backflux, 0.81 (95% CI: 0.61-1; P<0.05) for hepatocyte uptake fraction and 0.75 (95% CI: 0.54-1; P<0.05) for hepatic perfusion index (HPI), respectively. These initial results in patients with chronic liver diseases show that simultaneous quantification of hepatic perfusion and hepatocyte function is feasible with free breathing dynamic gadoxetic acid-enhanced MRI. Hepatocyte function parameters may be relevant to assess liver fibrosis severity.
Journal of Medical Engineering | 2013
Benjamin Leporq; Sorina Camarasu-Pop; Eduardo E. Davila-Serrano; Frank Pilleul; Olivier Beuf
An MR acquisition protocol and a processing method using distributed computing on the European Grid Infrastructure (EGI) to allow 3D liver perfusion parametric mapping after Magnetic Resonance Dynamic Contrast Enhanced (MR-DCE) imaging are presented. Seven patients (one healthy control and six with chronic liver diseases) were prospectively enrolled after liver biopsy. MR-dynamic acquisition was continuously performed in free-breathing during two minutes after simultaneous intravascular contrast agent (MS-325 blood pool agent) injection. Hepatic capillary system was modeled by a 3-parameters one-compartment pharmacokinetic model. The processing step was parallelized and executed on the EGI. It was modeled and implemented as a grid workflow using the Gwendia language and the MOTEUR workflow engine. Results showed good reproducibility in repeated processing on the grid. The results obtained from the grid were well correlated with ROI-based reference method ran locally on a personal computer. The speed-up range was 71 to 242 with an average value of 126. In conclusion, distributed computing applied to perfusion mapping brings significant speed-up to quantification step to be used for further clinical studies in a research context. Accuracy would be improved with higher image SNR accessible on the latest 3T MR systems available today.
NMR in Biomedicine | 2018
Angeline Nemeth; Berenice Segrestin; Benjamin Leporq; Amandine Coum; Giulio Gambarota; Kevin Seyssel; Martine Laville; Olivier Beuf; Hélène Ratiney
The composition of fatty acids in the body is gaining increasing interest, and can be followed up noninvasively by quantitative magnetic resonance spectroscopy (MRS). However, current MRS quantification methods have been shown to provide different quantitative results in terms of lipid signals, with possible varying outcomes for a given biological examination. Quantitative magnetic resonance imaging using multigradient echo sequence (MGE‐MRI) has recently been added to MRS approaches. In contrast, these methods fit the undersampled magnetic resonance temporal signal with a simplified model function (expressing the triglyceride [TG] spectrum with only three TG parameters), specific implementations and prior knowledge. In this study, an adaptation of an MGE‐MRI method to MRS lipid quantification is proposed.
NMR in Biomedicine | 2018
Maguelonne Pons; Benjamin Leporq; Liza Ali; Marianne Alison; Miguel Albuquerque; Michel Peuchmaur; Marie-Laurence Poli Mérol; Ulrich Blank; Simon A. Lambert; Alaa El Ghoneimi
Ureteropelvic junction obstruction constitutes a major cause of progressive pediatric renal disease. The biological mechanisms underlying the renal response to obstruction can be investigated using a clinically relevant mouse model of partial unilateral ureteral obstruction (pUUO). Renal function and kidney morphology data can be evaluated using renal ultrasound, scintigraphy and uro‐magnetic resonance imaging (uro‐MRI), but these methods are poorly linked to histological change and not all are quantitative. Here, we propose to investigate pUUO for the first time using an intravoxel incoherent motion diffusion sequence. The aim of this study was to quantitatively characterize impairment of the kidney parenchyma in the pUUO model. This quantitative MRI method was able to assess the perfusion and microstructure of the kidney without requiring the injection of a contrast agent. The results suggest that a perfusion fraction (f) reduction is associated with a decrease in the volume of the renal parenchyma, which could be related to decreased renal vascularization. The latter may occur before impairment by fibrosis and the findings are in accordance with the literature using the UUO mice model and, more specifically, on pUUO. Further investigation is required before this technique can be made available for the diagnosis and management of children with antenatal hydronephrosis and to select the optimal timing of surgery if required.