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Metabolic dysfunction-associated steatotic liver disease (MASLD) prevalence is increasing annually and affects over a third of US adults. MASLD can progress to metabolic dysfunction-associated steatohepatitis (MASH), characterized by severe hepatocyte injury, inflammation, and eventual advanced fibrosis or cirrhosis. MASH is predicted to become the primary cause of liver transplant by 2030. Although the etiology of MASLD/MASH is incompletely understood, dysregulated fatty acid oxidation is implicated in disease pathogenesis. Here, we develop a method for estimating hepatic β-oxidation from the metabolism of [D 15 ]octanoate to deuterated water and detection with deuterium magnetic resonance methods. Perfused livers from a mouse model of MASLD reveal dysregulated hepatic β-oxidation, findings that corroborate in vivo imaging. The high-fat-diet-induced MASLD mouse studies indicate that decreased β-oxidative efficiency in the fatty liver could serve as an indicator of MASLD progression. Furthermore, our method provides a clinically translatable imaging approach for determining hepatic β-oxidation efficiency., Competing Interests: Declaration of interests M.E.M. and R.M. are holders of patent ##T17984US002 related to metabolic imaging of HDO., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to investigate hyperpolarization and in vivo imaging of [ 15 N]carnitine, a novel endogenous MRI probe with long signal lifetime., Methods: L-[ 15 N]carnitine-d 9 was hyperpolarized by the method of dynamic nuclear polarization followed by rapid dissolution. The T 1 signal lifetimes were estimated in aqueous solution and in vivo following intravenous injection in rats, using a custom-built dual-tuned 15 N/ 1 H RF coil at 4.7 T. 15 N chemical shift imaging and 15 N fast spin-echo images of rat abdomen were acquired 3 minutes after [ 15 N]carnitine injection., Results: Estimated T 1 times of [ 15 N]carnitine at 4.7 T were 210 seconds (in H 2 O) and 160 seconds (in vivo), with an estimated polarization level of 10%. Remarkably, the [ 15 N]carnitine coherence was detectable in rat abdomen for 5 minutes after injection for the nonlocalized acquisition. No downstream metabolites were detected on localized or nonlocalized 15 N spectra. Diffuse liver enhancement was detected on 15 N fast spin-echo imaging 3 minutes after injection, with mean hepatic SNR of 18 ± 5 at a spatial resolution of 4 × 4 mm., Conclusion: This study showed the feasibility of hyperpolarizing and imaging the biodistribution of HP [ 15 N]carnitine., (© 2020 International Society for Magnetic Resonance in Medicine.)

Both spin-echo (SE) and ultra-short echo (UTE) based MRI sequences were used on a 7 T µMRI system to quantify T2, T1ρ and T1 relaxation times from articular cartilage to the cartilage-bone interface on canine humeral specimens at 19.5 µm pixel resolution. A series of five relaxation-weighted images were acquired to calculate one relaxation map (T2, T1ρ or T1), from which the depth-dependent profiles were examined between the SE method and the UTE method, over the entire non-calcified cartilage and within the cartilage-bone interface. SE-based methods enabled the quantification of relaxation profiles over the noncalcified cartilage, from 0 µm (articular surface) to approximately 460 µm in depth (near the end of radial zone). Most of the cartilage-bone interface was imaged by the UTE-based methods, to a tissue depth of about 810 µm. Pixel-by-pixel calculation of the relaxation times between the independent SE and UTE methods correlated well with each other. A better understanding of the tissue properties reliably over the cartilage-bone interface region by a non-invasive MRI approach could contribute to the clinical diagnostics of trauma-induced osteoarthritis., (Copyright © 2018 Elsevier Inc. All rights reserved.)