B Van Beers

Paris Diderot University, Lutetia Parisorum, Île-de-France, France

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Publications (254)599.94 Total impact

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    ABSTRACT: To evaluate the value of diffusion-weighted imaging (DWI) in detecting residual tumours (RTs) in colorectal liver metastases (CLMs) following chemotherapy, with a focus on tumour periphery. From January 2009-January 2012, 57 patients who underwent liver resection for CLMs with preoperative MRI (<3 months) including DWI were retrospectively included. CLMs were classified into three response groups on pathology: (1) major histological (MHR, RTs ≤ 10 %), (2) partial histological (PHR, RT = 10-49 %), and (3) no histological (NHR, RT ≥ 50 %). On DWI, regions of interest (ROIs) were drawn around the entire tumour and tumour periphery. Apparent diffusion (ADC) and pure diffusion (D) coefficients were calculated using a monoexponential fit, and compared using Kruskal-Wallis test on a lesion-per-lesion analysis. 111 CLMs were included. Fourteen (12.5 %), 42 (38 %) and 55 (49.5 %) CLMs presented a MHR, PHR and NHR, respectively. ADC and D of the peripheral ROIs were significantly higher in the MHR group (P = 0.013/P = 0.013). ADC and D from the entire tumour were not significantly different among the groups (P = 0.220/P = 0.103). In CLM treated with chemotherapy, ADC and D values from the entire tumour are not related to the degree of RT, while peripheral zone diffusion parameters could help identify metastases with MHR. • Peripheral ADC and D of CLMs were higher with major pathological responses. • Global ADC and D of CLMs were not different according to residual tumour. • Diffusion-weighted images of CLM periphery could be an interesting biomarker of MHR. • Diffusion-weighted images could be used to help tailor treatment.
    European Radiology 05/2015; DOI:10.1007/s00330-015-3800-6 · 4.34 Impact Factor
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    ABSTRACT: Purpose: To compare qualitative and quantitative magnetic resonance (MR) imaging characteristics of hepatic hemangiomas in patients with normal, fibrotic and cirrhotic livers. Meterials and Methods: Retrospective, institutional review board approved study (waiver of informed consent). Eighty-nine consecutive patients with 231 hepatic hemangiomas who underwent liver MR imaging for lesion characterization were included. Lesions were classified into three groups according to the patients' liver condition: no underlying liver disease (group 1), fibrosis (group 2) and cirrhosis (group 3). Qualitative and quantitative characteristics (number, size, signal intensities on T1-, T2-, and DW MR images, T2 shine-through effect, enhancement patterns (classical, rapidly filling, delayed filling), and ADC values) were compared. Results: There were 160 (69%), 45 (20%), and 26 (11%) hemangiomas in groups 1, 2 and 3, respectively. Lesions were larger in patients with normal liver (group 1 vs. groups 2 and 3; P=.009). No difference was found between the groups on T2-weighted images (fat-suppressed fast spin-echo (P=.82) and single-shot (P=.25)) and in enhancement patterns (P=.56). Mean ADC values of hemangiomas were similar between groups 1, 2 and 3 (2.11±.52×10-3mm2/s, 2.1±.53×10-3mm2/s and 2.14±.44×10-3mm2/s, P=87, respectively). T2 shine-through effect was less frequently observed in cirrhosis (P=.02). Conclusion: MR imaging characteristics of hepatic hemangioma were similar in patients with normal compared to fibrotic and cirrhotic livers. Smaller lesion size was observed with liver disease and less T2 shine-through effect was seen in hemangiomas developed on cirrhosis, the latter being an important finding to highlight in these patients at risk of developing hepatocellular carcinoma.
    European journal of radiology 01/2015; DOI:10.1016/j.ejrad.2015.01.016 · 2.16 Impact Factor
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    Bernard E. Van Beers, Jean-Luc Daire, Philippe Garteiser
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    ABSTRACT: Newly developed or advanced methods at ultrasonography and MR imaging provide combined anatomical and quantitative functional information regarding diffuse and focal liver diseases. Dynamic contrast-enhanced ultrasonography may improve tumor characterization and ultrasound elastography has a central role for staging liver fibrosis and an increasing role in grading portal hypertension. In clinical practice, MR imaging examinations currently include diffusion-weighted and dynamic MR imaging enhanced with extracellular or hepatobiliary contrast agents. Moreover, quantitative parameters obtained at diffusion-weighted MR imaging, dynamic contrast-enhanced MR imaging and MR elastography have the potential to further characterize diffuse and focal liver diseases by adding information about tissue cellularity, perfusion, hepatocyte transport function and visco-elasticity. The multiparametric capability of ultrasonography and more markedly of MR imaging gives the opportunity of high diagnostic performance by combining imaging biomarkers. The image acquisition and post-processing methods should be further standardized and validated in multicenter trials.
    Journal of Hepatology 10/2014; 62(3). DOI:10.1016/j.jhep.2014.10.014 · 10.40 Impact Factor
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    ABSTRACT: Purpose To compare the value of enhancement and pharmacokinetic parameters measured at dynamic gadoxetate-enhanced magnetic resonance (MR) imaging in determining hepatic organic anion transporter expression in control rats and rats with advanced liver fibrosis. Materials and Methods Institutional animal review board approval was received before the study began. Advanced liver fibrosis was created in rats by means of carbon tetrachloride injections over an 8-week period. In 17 rats with liver fibrosis and eight control rats, dynamic gadoxetate-enhanced MR images of the liver were obtained during 1 hour after injection of 0.025 mmol gadoxetate per kilogram of body weight. Enhancement parameters (maximum enhancement [ Emax maximum enhancement ], time to peak [ Tmax time to peak ], and elimination half-life) were measured on enhancement-versus-time curves, and pharmacokinetic parameters (hepatic extraction fraction [ HEF hepatic extraction fraction ] and mean residence time [ MRT mean residence time ]) were obtained by means of deconvolution analysis of the concentration-versus-time curves in the liver and the portal vein. The parameters were correlated at simple and multiple regression analysis with the expression of the hepatic anion uptake transporter organic anion-transporting polypeptide 1A1 ( Oatp organic anion-transporting polypeptide 1a1), the hepatobiliary transporter multidrug resistance-associated protein 2 ( Mrp multidrug resistance-associated protein 2), and the backflux transporter Mrp multidrug resistance-associated protein 4, as determined with reverse transcription polymerase chain reaction. Results In rats with advanced liver fibrosis, the Emax maximum enhancement , Tmax time to peak , HEF hepatic extraction fraction , and MRT mean residence time decreased significantly relative to those in control rats, whereas the elimination half-life increased significantly. The enhancement and pharmacokinetic parameters correlated significantly with the expression of the transporters at simple regression analysis. At multiple regression analysis, HEF hepatic extraction fraction was the only parameter that was significantly associated with the expression of Oatp organic anion-transporting polypeptide 1a1 and Mrp multidrug resistance-associated protein 2 (P < .001, r = 0.74 and P < .001, r = 0.70, respectively). Conclusion The pharmacokinetic parameter HEF hepatic extraction fraction at dynamic gadoxetate-enhanced MR imaging is independently correlated with hepatic organic anion transporter expression. © RSNA, 2014.
    Radiology 10/2014; DOI:10.1148/radiol.14140313 · 6.21 Impact Factor
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    ABSTRACT: To prospectively assess the stiffness of incidentally discovered focal liver lesions (FLL) with no history of chronic liver disease or extrahepatic cancer using shearwave elastography (SWE).
    European Radiology 09/2014; 25(2). DOI:10.1007/s00330-014-3370-z · 4.34 Impact Factor
  • 56th AAPM Annual Meeting and Exhibition, Austin, TX, USA; 07/2014
  • International Society for Magnetic Resonance in Medicine (ISMRM), Milan, Italy; 05/2014
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    ABSTRACT: PURPOSE: The presence of micro-obstacles can influence the propagation of the shear waves 1 and hence alter the apparent mechanical properties 2 as assessed via Magnetic Resonance Elastography (MRE). Disease or therapies can change the mechanical integrity and organization of vascular structures. If blood vessels represent a source for wave scattering (i.e represent micro-obstacles), MRE should be able to sense these changes. We follow the hypothesis that the presence of an underlying fractal-like stiff structure is capable of generating on the macroscopic scale apparent power law behavior in an otherwise non-dispersive material. To verify this hypothesis, multi-frequency MRE was performed to quantify alteration of the shear wave speed (Cs) due to the presence of vascular outgrowth using a rat aortic ring model. The model is based on the capacity of fragments of aorta to generate vascular outgrowth once cultivated in Matrigel 3 . METHODS: Eighteen fragments of rat aortas were immersed in Matrigel and cultivated. At 1 day (D1, n=6), 5 days (D5, n=6) and 8 days (D8, n=6) after their inclusion, the fragments were imaged at 7T (Bruker, Pharmascan). T2-weighted images (113μm in plane resolution) and 3D steady-state MRE at different 5 frequencies (ω=100, 115, 125, 135 and 150Hz; 300μm in plane resolution) were recorded 4
    ISMRM International Society for Magnetic Resonance in Medicine (Milan, It, 2014); 05/2014
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    ABSTRACT: To assess in a high-resolution model of thin liver rat slices which viscoelastic parameter at three-dimensional multifrequency MR elastography has the best diagnostic performance for quantifying liver fibrosis. The study was approved by the ethics committee for animal care of our institution. Eight normal rats and 42 rats with carbon tetrachloride induced liver fibrosis were used in the study. The rats were sacrificed, their livers were resected and three-dimensional MR elastography of 5±2 mm liver slices was performed at 7T with mechanical frequencies of 500, 600 and 700 Hz. The complex shear, storage and loss moduli, and the coefficient of the frequency power law were calculated. At histopathology, fibrosis and inflammation were assessed with METAVIR score, fibrosis was further quantified with morphometry. The diagnostic value of the viscoelastic parameters for assessing fibrosis severity was evaluated with simple and multiple linear regressions, receiver operating characteristic analysis and Obuchowski measures. At simple regression, the shear, storage and loss moduli were associated with the severity of fibrosis. At multiple regression, the storage modulus at 600 Hz was the only parameter associated with fibrosis severity (r = 0.86, p<0.0001). This parameter had an Obuchowski measure of 0.89+/-0.03. This measure was significantly larger than that of the loss modulus (0.78+/-0.04, p = 0.028), but not than that of the complex shear modulus (0.88+/-0.03, p = 0.84). Our high resolution, three-dimensional multifrequency MR elastography study of thin liver slices shows that the storage modulus is the viscoelastic parameter that has the best association with the severity of liver fibrosis. However, its diagnostic performance does not differ significantly from that of the complex shear modulus.
    PLoS ONE 04/2014; 9(4):e94679. DOI:10.1371/journal.pone.0094679 · 3.53 Impact Factor
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    ABSTRACT: To assess the value of the liver and spleen viscoelastic parameters at multifrequency MR elastography to determine the degree of portal hypertension and presence of high-risk oesophageal varices in patients with cirrhosis. From January to September 2012, 36 consecutive patients with cirrhosis evaluated for transplantation were prospectively included. All patients underwent hepatic venous pressure gradient (HVPG) measurements and endoscopy to assess oesophageal varices. Multifrequency MR elastography was performed within the liver and spleen. The shear, storage and loss moduli were calculated and compared to the HVPG with Spearman coefficients and multiple regressions. Patients with and without severe portal hypertension and high-risk varices were compared with Mann-Whitney tests, logistic regression and ROC analysis. The liver storage and loss moduli and the spleen shear, storage and loss moduli correlated with the HVPG. At multiple regression, only the liver and the spleen loss modulus correlated with the HVPG (r = 0.44, p = 0.017, and r = 0.57, p = 0.002, respectively). The spleen loss modulus was the best parameter for identifying patients with severe portal hypertension (p = 0.019, AUROC = 0.81) or high-risk varices (p = 0.042, AUROC = 0.93). The spleen loss modulus appears to be the best parameter for identifying patients with severe portal hypertension or high-risk varices. 1. Noninvasive HVPG assessment can be performed with liver and spleen MR elastography 2. The spleen loss modulus enables the detection of high-risk oesophageal varices 3. The spleen loss modulus enables the detection of severe portal hypertension.
    European Radiology 03/2014; DOI:10.1007/s00330-014-3124-y · 4.34 Impact Factor
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    ABSTRACT: Detection and characterization of focal lesions in the cirrhotic liver may pose a diagnostic dilemma. Several benign and malignant lesions may be found in a cirrhotic liver along with hepatocellular carcinoma (HCC), and may exhibit typical or atypical imaging features. In this pictorial essay, we illustrate computed tomography and magnetic resonance imaging findings of lesions such as simple bile duct cysts, hemangioma, focal nodular hyperplasia-like nodules, peribiliary cysts, intrahepatic cholangiocarcinoma, lymphoma, and metastases, all of which occur in cirrhotic livers with varying prevalences. Pseudolesions, such as perfusion anomalies, focal confluent fibrosis, and segmental hyperplasia, will also be discussed. Imaging characterization of non-HCC lesions in cirrhosis is important in formulating an accurate diagnosis and triaging the patient towards the most appropriate management.
    Diagnostic and interventional radiology (Ankara, Turkey) 02/2014; 20(3). DOI:10.5152/dir.2014.13184 · 1.43 Impact Factor
  • Bernard E Van Beers
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    ABSTRACT: Summary By showing that intravoxel incoherent motion parameters at diffusion-weighted magnetic resonance (MR) imaging may be indicators of the microcirculatory changes in patients with nonalcoholic steatohepatitis and fatty liver disease, Joo et al have taken a step forward in the validation of quantitative MR imaging parameters as biomarkers of nonalcoholic steatohepatitis and fatty liver disease. Further steps, including standardization, validation, and multiparametric imaging, must be taken before these parameters can be used as biomarkers in clinical practice.
    Radiology 01/2014; 270(1):1-2. DOI:10.1148/radiol.13132294 · 6.21 Impact Factor
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    ABSTRACT: To determine the frequency and factors associated with the presence of T2 shine-through effect in hepatic hemangiomas on diffusion-weighted (DW) magnetic resonance (MR) sequences. This retrospective study was approved by institutional review board with waiver of informed consent. One hundred forty-nine consecutive patients with 388 hepatic hemangiomas who underwent a liver MR between January 2010 and November 2011 were included. MR analysis evaluated the lesion characteristics (signal intensities and enhancement patterns (classical, rapidly filling, delayed filling)), the presence of T2 shine-through effect on DW sequences (b values of 0, 150, and 600s/mm(2)), and apparent diffusion coefficient (ADC) values. Multivariate analysis was performed to study the factors associated with the T2 shine-through effect. T2 shine-through effect was observed in 204/388 (52.6%) of hepatic hemangiomas and in 100 (67.1%) patients. Mean ADC value of hemangiomas with T2 shine-through effect was significantly lower than hemangiomas without (2.0±0.48 vs 2.38±0.45, P<.0001). On multivariate analysis, high signal intensity on fat-suppressed T2-weighted fast spin-echo images, hemangiomas with classical or delayed enhancement, and the ADC of the liver were the only significant factors associated with T2 shine-through effect. T2 shine-through effect is commonly observed in hepatic hemangiomas and is related to hemangiomas characteristics. Radiologists should be aware of this phenomenon which could lead to misdiagnosis. Its presence should not question the diagnosis of hemangiomas when typical MR findings are found.
    European journal of radiology 12/2013; 83(3). DOI:10.1016/j.ejrad.2013.11.023 · 2.16 Impact Factor
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    ABSTRACT: PURPOSE To assess the value of enhancement and pharmacokinetic parameters measured at dynamic gadoxetate-enhanced MR imaging in the determination of hepatic organic anion transport function in rat liver cirrhosis. METHOD AND MATERIALS Institutional animal review board approval was received prior to the start of the study. Carbon tetrachloride induced liver cirrhosis was obtained in 21 rats. Nine normal rats were used as control. Dynamic gadoxetate-enhanced MR images of the liver were obtained during one hour after injection of 0.025mmol/kg gadoxetate. Enhancement parameters (maximal enhancement, time to peak and elimination half-life) were measured on the enhancement versus time curves and pharmacokinetic parameters (hepatic extraction fraction and mean residence time) were obtained after deconvolution analysis of the concentration versus time curves in the liver and the portal vein. The parameters were correlated with simple and multiple regression analysis to the expression of the hepatic anion uptake transporter Oatp1a1, hepatobiliary transporter Mrp2, and backflux transporter Mrp4 determined with real time polymerase chain reaction RESULTS In rats with cirrhosis, the maximal enhancement and time to peak decreased significantly relative to control rats, whereas the elimination half-life increased significantly. Similarly, the hepatic extraction fraction decreased and the mean residence time increased significantly. Several enhancement and pharmacokinetic parameters correlated significantly with the transporter expression at simple regression analysis (p < 0.05). At multiple regression analysis, only the hepatic extraction fraction correlated significantly with the expression of Oatp1a1 and Mrp2 with r values > 0.7, as did the mean residence time with Mrp4. The respective values were p < 10-4, r = 0.744; p < 10-4, r = 0.911, and p = 0.001, r = 0.921. CONCLUSION The pharmacokinetic parameters, hepatic extraction fraction and mean residence time, determined at dynamic gadoxetate-enhanced MR imaging, are markers of the changes of hepatic organic anion transporter expression in liver cirrhosis. CLINICAL RELEVANCE/APPLICATION DHCE-MRI has the potential to assess hepatocyte transporter function in liver cirrhosis.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE To assess the liver and spleen viscoelastic properties associated with portal hypertension using magnetic resonance elastography (MRE) in a consecutive series of patients with chronic liver disease METHOD AND MATERIALS From January to September 2012, patients with histologically proven cirrhosis and registered on the pre-transplant list of our institution were prospectively included. Clinical and biological data including presence and severity of ascites, esophageal varices (graded on an upper GI endoscopy), Child-Pugh and MELD scores were recorded. All patients underwent a transjugular hepatic venous portal gradient (HVPG) measurement (mmHg) and a MRE examination on the same week. MRE sequence (28, 56, and 84 Hz) was performed on a 1.5 T imaging scanner. Two mechanical transducers placed on both sides of the patients were used to analyze liver and spleen stiffness (FOV: 320mm2, matrix: 80x80, TR/TE: var/9.21ms, 8 dynamics, acquisition time: 1 min). Complex shear modulus was extracted, and the elasticity (Gd) and viscosity (Gl) were calculated. Correlations between the viscoelastic parameters and the clinico-biological data were performed using the Spearman coefficient test. RESULTS 42 patients (31 males, 76%) with a mean age of 55.5 (range: 31-69) were included. Six patients (14%) were excluded due to incomplete MR examination. Cirrhosis was related to alcohol consumption (n=16) and HCV (n=9). Child score was A (n=7), B (n=13) and C (n=16). Median MELD score was 15 (range: 6-33). Median HVPG was 16mmHg (range: 6-36). Ascites was detected in 25 patients (69%). 29 patients had esophageal varices (including 14 patients with grade 3). There was no correlation between liver elasticity or liver viscosity and any of the clinicobiological parameter (MELD and Child-Pugh scores, ascites, esophageal varices, and HVPG). Spleen elasticity and spleen viscosity significantly correlated with HVPG (r=0.44, p=0.02 and r=0.53, p=0.0041, respectively) but not with the other parameters (MELD and Child-Pugh scores, ascites, and esophageal varices). CONCLUSION The spleen viscoelastic properties assessed by MRE are correlated with the hepatic venous portal gradient in patients with chronic liver disease. CLINICAL RELEVANCE/APPLICATION Our results indicate that the spleen visco-elasticity assessed by MRE is related to the severity of portal hypertension, and might constitute an interesting biomarker in severe chronic liver disease
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: L’imagerie de perfusion hépatique est une modalité d’étude quantitative et fonctionnelle. La difficulté, dans le cas du foie, vient de son double apport vasculaire, des artéfacts liés aux mouvements respiratoires et aux capillaires sinusoïdes fenêtrés laissant diffuser le traceur. On peut étudier la perfusion hépatique en échographie, scanner ou IRM et chaque technique présente limites et spécificités. Les grandes indications en hépatologie sont l’oncologie (détection, caractérisation et réponse tumorale) et l’exploration non invasive des maladies hépatiques chroniques. Des efforts de standardisation sont nécessaires concernant les modalités d’acquisition et la modélisation pour permettre une diffusion des résultats et une utilisation plus large.
    12/2013; DOI:10.1016/j.jradio.2013.05.006
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    ABSTRACT: PURPOSE To develop a high-resolution MRE-assessed fibrous liver analysis in an ex-vivo rat model using <5mm thin-liver slices METHOD AND MATERIALS Fibrosis was induced in rats using CCl4 intoxication. Rats were anesthetized and sacrificed, livers were resected and <5mm liver slices were obtained. Eight control rats and 42 fibrotic rats were included to analyze 6 rats per week from 2 to 8 weeks after initiation of fibrosis induction. Fibrosis and inflammation were assessed using the METAVIR score. The vibration was generated by a toothpick placed in the center of the liver slices. An electromagnetic shaker was used to transmit mechanical vibrations via a carbon fiber rod to the toothpick. MRE was performed on a 7T imaging scanner. The spin echo MRE sequence was acquired with a mechanical excitation of 600Hz for the three spatial directions of motion with a resolution of 400μm, and with the following parameters: FOV: 25mm2, matrix 64x64, TR/TE: 503/25.8ms, 8 dynamics. Complex shear modulus was extracted, and the elasticity (Gd) and viscosity (Gl) were calculated. Statistical analysis of the relation between the viscoelastic parameters and the fibrosis stages was performed using ANOVA and Bonferroni-Dunn’s post-hoc tests. RESULTS Rats had different stages of fibrosis: F0 (n=8), F1 (n=8), F2 (n=3), F3 (n=8), and F4 (n=15). Three (6%) rats were excluded due to technical problems during MR. Liver elasticity significantly increased with the progression of fibrosis, with mean Gd values of 2.7 (+/-0.45), 2.9 (+/-0.3), 3.0 (+/-0.16), 3.2 (+/- 0.42), and 3.8 (+/-0.44) kPa for F0, F1, F2, F3 and F4 livers respectively (p<0.0001). Post-hoc test showed significant differences between F0 and F4, F1 and F4, F2 and F4 (p<0.001). Inflammation was absent or mild (A0-1) and did not influence the Gd values. Viscosity was similar for F0 to F2 stages (mean Gl values of 1.6 +/-0.2kPa) and significantly increased in F3 (1.8 +/-0.2kPa), and F4 (2.1 +/-0.2kPa, p<0.0001). CONCLUSION Our ex vivo thin-liver slice rat model allowed accurate analysis of liver stiffness on MR at 7T. CLINICAL RELEVANCE/APPLICATION MRE could be a non-invasive biomarker for evaluation of liver fibrosis but requires further clinical and experimental explorations. Our results show a preclinical validation in a model of pure liver f
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE: The presence of micro-obstacles can influence the propagation of the shear waves 1 and hence alter the apparent mechanical properties 2 as assessed via Magnetic Resonance Elastography (MRE). Disease or therapies can change the mechanical integrity and organization of vascular structures. If blood vessels represent a source for wave scattering (i.e represent micro-obstacles), MRE should be able to sense these changes. We follow the hypothesis that the presence of an underlying fractal-like stiff structure is capable of generating on the macroscopic scale apparent power law behavior in an otherwise non-dispersive material. To verify this hypothesis, multi-frequency MRE was performed to quantify alteration of the shear wave speed (Cs) due to the presence of vascular outgrowth using a rat aortic ring model. The model is based on the capacity of fragments of aorta to generate vascular outgrowth once cultivated in Matrigel 3 . METHODS: Eighteen fragments of rat aortas were immersed in Matrigel and cultivated. At 1 day (D1, n=6), 5 days (D5, n=6) and 8 days (D8, n=6) after their inclusion, the fragments were imaged at 7T (Bruker, Pharmascan). T2-weighted images (113μm in plane resolution) and 3D steady-state MRE at different 5 frequencies (ω=100, 115, 125, 135 and 150Hz; 300μm in plane resolution) were recorded 4
    ESMRMB European Society for Magnetic Resonance in Medicine and Biology (Toulouse, Fr, 2013); 10/2013
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    ABSTRACT: In MR elastography (MRE), periodic tissue motion is phase encoded using motion-encoding gradients synchronized to an externally applied periodic mechanical excitation. Conventional methods result in extended scan time for quality phase images, thus limiting the broad application of MRE in the clinic. For practical scan times, researchers have been relying on one-dimensional or two-dimensional motion-encoding, low-phase sampling and a limited number of slices, and artifact-prone, single-shot, echo planar imaging (EPI) readout. Here, we introduce a rapid multislice pulse sequence capable of three-dimensional motion encoding that is also suitable for simultaneously encoding motion with multiple frequency components. This sequence is based on a gradient-recalled echo (GRE) sequence and exploits the principles of fractional encoding. This GRE MRE pulse sequence was validated as capable of acquiring full three-dimensional motion encoding of isotropic voxels in a large volume within less than a minute. This sequence is suitable for monofrequency and multifrequency MRE experiments. In homogeneous paraffin phantoms, the eXpresso sequence yielded similar storage modulus values as those obtained with conventional methods, although with markedly reduced variances (7.11 ± 0.26 kPa for GRE MRE versus 7.16 ± 1.33 kPa for the conventional spin-echo EPI sequence). The GRE MRE sequence obtained better phase-to-noise ratios than the equivalent spin-echo EPI sequence (matched for identical acquisition time) in both paraffin phantoms and in vivo data in the liver (59.62 ± 11.89 versus 27.86 ± 3.81, 61.49 ± 14.16 versus 24.78 ± 2.48 and 58.23 ± 10.39 versus 23.48 ± 2.91 in the X, Y and Z components, respectively, in the case of liver experiments). Phase-to-noise ratios were similar between GRE MRE used in monofrequency or multifrequency experiments (75.39 ± 14.93 versus 86.13 ± 18.25 at 28 Hz, 71.52 ± 24.74 versus 86.96 ± 30.53 at 56 Hz and 95.60 ± 36.96 versus 61.35 ± 26.25 at 84Hz, respectively). Copyright © 2013 John Wiley & Sons, Ltd.
    NMR in Biomedicine 10/2013; 26(10). DOI:10.1002/nbm.2958 · 3.56 Impact Factor
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    ABSTRACT: Magnetic resonance (MR) techniques allow noninvasive fat quantification. We aimed to investigate the accuracy of MR imaging (MRI), MR spectroscopy (MRS) and histological techniques to detect early-onset liver steatosis in three rat phenotypes assigned to an experimental glucolipotoxic model or a control group. This study was approved by the institutional committee for the protection of animals. Thirty-two rats (13 young Wistar, 6 old Wistar and 13 diabetic Goto-Kakizaki rats) fed a standard diet were assigned to a 72h intravenous infusion of glucose and Intralipid fat emulsion or a saline infusion. Plasma insulin levels were measured. Steatosis was quantified in ex vivo livers with gradient-recalled multi-echo MRI, MRS and histology as fat fractions (FF). A significant correlation was found between multi-echo MRI-FF and MRS-FF (r=0.81, p<0.01) and a weaker correlation was found between histology and MRS-FF (r=0.60, p<0.01). MRS and MRI accurately distinguished young Wistar and Goto-Kakizaki rats receiving the glucose+Intralipid infusion from those receiving the saline control whereas histology did not. Significant correlations were found between MRI or MRS and insulin plasma level (r=0.63, p<0.01; r=0.57, p<0.01), and between MRI or MRS and C-peptide concentration (r=0.54, p<0.01; r=0.44, p<0.02). Multi-echo MRI and MRS may be more sensitive to measure early-onset liver steatosis than histology in an experimental glucolipotoxic rat model.
    Metabolism: clinical and experimental 09/2013; DOI:10.1016/j.metabol.2013.08.003 · 3.61 Impact Factor

Publication Stats

4k Citations
599.94 Total Impact Points

Institutions

  • 2008–2014
    • Paris Diderot University
      Lutetia Parisorum, Île-de-France, France
  • 2013
    • University of Coimbra
      • Center for Neurosciences and Cell Biology
      Coímbra, Coimbra, Portugal
  • 2010–2013
    • Assistance Publique – Hôpitaux de Paris
      • Department of Radiology
      Lutetia Parisorum, Île-de-France, France
  • 2009–2013
    • Unité Inserm U1077
      Caen, Lower Normandy, France
  • 2011
    • French Institute of Health and Medical Research
      Lutetia Parisorum, Île-de-France, France
  • 1988–2011
    • Catholic University of Louvain
      • • Laboratory of Pediatric Hepatology and Cell Therapy
      • • Department of Radiology and Medical Imaging - RAIM
      Walloon Region, Belgium
  • 1992–2010
    • Cliniques Universitaires Saint-Luc
      • • Department of Medical Imaging
      • • Division of Radiology
      • • Division of Gastroenterology
      Bruxelles, Brussels Capital Region, Belgium
    • Institut de Cancérologie Gustave Roussy
      Villejuif, Île-de-France, France
  • 2005
    • Vanderbilt University
      • Department of Biomedical Engineering
      Нашвилл, Michigan, United States
  • 1988–1994
    • Centre Hospitalier Universitaire Mont-Godinne
      Yvoir, Walloon Region, Belgium
  • 1990
    • University Hospital Brussels
      • Department of Radiology
      Bruxelles, Brussels Capital Region, Belgium
  • 1988–1989
    • Université Paris-Sud 11
      Orsay, Île-de-France, France