Browsing by Author "Lavin, Begoña"

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    Characterization of hepatic fatty acids using magnetic resonance spectroscopy for the assessment of treatment response to metformin in an eNOS−/− mouse model of metabolic nonalcoholic fatty liver disease/nonalcoholic steatohepatitis
    (2023) Lavin, Begoña; Eykyn, Thomas; Phinikaridou, Alkystis; Xavier, Aline; Kumar, Shravan; Buqué, Xabier; Aspichueta, Patricia; Sing-Long C., Carlos A.; Arrese, Marco; Botnar, René Michael; Andía Kohnenkampf, Marcelo Edgardo
    Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide. Liver biopsy remains the gold standard for diagnosis and staging of disease. There is a clinical need for noninvasive diagnostic tools for risk stratification, follow-up, and monitoring treatment response that are currently lacking, as well as preclinical models that recapitulate the etiology of the human condition. We have characterized the progression of NAFLD in eNOS−/− mice fed a high fat diet (HFD) using noninvasive Dixon-based magnetic resonance imaging and single voxel STEAM spectroscopy-based protocols to measure liver fat fraction at 3 T. After 8 weeks of diet intervention, eNOS−/− mice exhibited significant accumulation of intra-abdominal and liver fat compared with control mice. Liver fat fraction measured by 1H-MRS in vivo showed a good correlation with the NAFLD activity score measured by histology. Treatment of HFD-fed NOS3−/− mice with metformin showed significantly reduced liver fat fraction and altered hepatic lipidomic profile compared with untreated mice. Our results show the potential of in vivo liver MRI and 1H-MRS to noninvasively diagnose and stage the progression of NAFLD and to monitor treatment response in an eNOS−/− murine model that represents the classic NAFLD phenotype associated with metabolic syndrome.
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    Initial results of the Hyperion II DPET insert for simultaneous PET-MRI applied to atherosclerotic plaque imaging in New-Zealand white rabbits
    (IOP Publishing Ltd, 2024) Gebhardt, Pierre; Lavin, Begoña; Phinikaridou, Alkystis; Mackewn, Jane E.; Henningsson, Markus; Schug, David; Salomon, Andre; Marsden, Paul K.; Schulz, Volkmar; Botnar, René Michael
    Objective. In preclinical research, in vivo imaging of mice and rats is more common than any other animal species, since their physiopathology is very well-known and many genetically altered disease models exist. Animal studies based on small rodents are usually performed using dedicated preclinical imaging systems with high spatial resolution. For studies that require animal models such as mini-pigs or New-Zealand White (NZW) rabbits, imaging systems with larger bore sizes are required. In case of hybrid imaging using positron emission tomography (PET) and magnetic resonance imaging (MRI), clinical systems have to be used, as these animal models do not typically fit in preclinical simultaneous PET-MRI scanners. Approach. In this paper, we present initial imaging results obtained with the Hyperion IID PET insert which can accommodate NZW rabbits when combined with a large volume MRI RF coil. First, we developed a rabbit-sized image quality phantom of comparable size to a NZW rabbit in order to evaluate the PET imaging performance of the insert under high count rates. For this phantom, radioactive spheres with inner diameters between 3.95 and 7.86mm were visible in a warm background with a tracer activity ratio of 4.1 to 1 and with a total 18F activity in the phantom of 58MBq at measurement start. Second, we performed simultaneous PET-MR imaging of atherosclerotic plaques in a rabbit in vivo using a single injection containing 18F-FDG for detection of inflammatory activity, and Gd-ESMA for visualization of the aortic vessel wall and plaques with MRI. Main results. The fused PET-MR images reveal 18F-FDG uptake within an active plaques with plaque thicknesses in the sub-millimeter range. Histology showed colocalization of 18F-FDG uptake with macrophages in the aortic vessel wall lesions. Significance. Our initial results demonstrate that this PET insert is a promising system for simultaneous high-resolution PET-MR atherosclerotic plaque imaging studies in NZW rabbits.
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    MRI with gadofosveset : a potential marker for permeability in myocardial infarction
    (2018) Lavin, Begoña; Protti, Andrea; Lorrio, Silvia; Dong, Xuebin; Phinikaridou, Alkystis; Botnar, René Michael; Shah, Ajay
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    Simultaneous comprehensive liver T1, T2, , T1ρ, and fat fraction characterization with MR fingerprinting
    (2022) Velasco, Carlos; Cruz, Gastão; Jaubert, Olivier; Lavin, Begoña; Botnar, René Michael; Prieto Vásquez, Claudia
    Purpose: To develop a novel simultaneous co-registered T1, T2, urn:x-wiley:07403194:media:mrm29089:mrm29089-math-0811, T1ρ, and fat fraction abdominal MR fingerprinting (MRF) approach for fully comprehensive liver-tissue characterization in a single breath-hold scan. Methods: A gradient-echo liver MRF sequence with low fixed flip angle, multi-echo radial readout, and varying magnetization preparation pulses for multiparametric encoding is performed at 1.5 T. The urn:x-wiley:07403194:media:mrm29089:mrm29089-math-0011 and fat fraction are estimated from a graph/cut water/fat separation method using a six-peak fat model. Water/fat singular images obtained are then matched to an MRF dictionary, estimating water-specific T1, T2, and T1ρ. The proposed approach was tested in phantoms and 10 healthy subjects and compared against conventional sequences. Results: For the phantom studies, linear fits show excellent coefficients of determination (r2 > 0.9) for every parametric map. For in vivo studies, the average values measured within regions of interest drawn on liver, spleen, muscle, and fat are statistically different from the reference scans (p < 0.05) for T1, T2, and T1⍴ but not for urn:x-wiley:07403194:media:mrm29089:mrm29089-math-0012 and fat fraction, whereas correlation between MRF and reference scans is excellent for each parameter (r2 > 0.92 for every parameter). Conclusion: The proposed multi-echo inversion-recovery, T2, and T1⍴ prepared liver MRF sequence presented in this work allows for quantitative T1, T2, urn:x-wiley:07403194:media:mrm29089:mrm29089-math-0013, T1⍴, and fat fraction liver-tissue characterization in a single breath-hold scan of 18 seconds. The approach showed good agreement and correlation with respect to reference clinical maps.