De Feyter, H. M. | Search bioRxiv

bioRxiv2026

Challenges and Solutions in Quantifying Brain β-Hydroxybutyrate (BHB) with 1H-MRS Following Oral Keto-Ester Consumption

Purpose{beta}-hydroxybutyrate (BHB), a ketone body and alternative cerebral energy substrate, can be measured in vivo using J-difference edited proton magnetic resonance spectroscopy (1H-MRS). Oral ketone supplementation with substrates such as the ketone monoester (R)-3-hydroxybutyl-(R)-3-hydroxybutyrate (KME) and 1,3-butanediol (BD) have gained attention as a mechanism to elevate circulating BHB and induce ketosis without dietary restrictions. Elevated brain ketone availability is of growing therapeutic interest as a strategy to support neuronal energetics in conditions such as epilepsy, neurodegenerative disease, and alcohol use disorder (AUD). However, both pathways introduce BD into the bloodstream, which crosses the blood-brain barrier. Critically, BD exhibits a spectral signature that closely resembles the prominent BHB peak in JDE-MR spectroscopic imaging (MRSI), identified in a pilot AUD study. MethodsTwo separate JDE-MRSI acquisitions tailored for BHB and BD editing were implemented, exploiting frequency separation between the BHB (4.14ppm) and BD (3.95ppm) coupling partners of the observed 1.2ppm resonance to independently quantify each metabolite. ResultsBrain BD concentrations (0.25-0.58mM) were comparable to or exceeded corresponding BHB concentrations (0.20-0.27mM) in all volunteers after consumption of a single dose of the KME, indicating that BD constitutes a major fraction of the signal conventionally attributed to BHB. Combined BHB+BD concentrations ([~]0.45-0.85mM) were consistent with brain BHB values reported in prior studies employing similar doses of the KME, indicating that those measurements likely reflect a combined BHB+BD signal. ConclusionsSeparate quantification of the two metabolites is important for interpreting brain ketone studies and for understanding the full pharmacology of KME supplementation.

neuroscience↗

bioRxiv2025

Oral Intake of Deuterated Choline at Clinical Dose for Metabolic Imaging of Brain Tumors

Accurate characterization and imaging of brain tumors are essential for effective treatment planning and monitoring. While MRI is widely used because of its high sensitivity for detecting lesions, the range of available types of MR image contrast does not offer high specificity for tumors. Deuterium metabolic imaging (DMI), which combines 2H magnetic resonance spectroscopic imaging (MRSI) with administration of deuterium-labeled substrates, is a relatively new imaging approach that could provide unique, complementary information to anatomical MRI. Preclinical studies have demonstrated the feasibility of DMI with intravenous (IV) administration of deuterated choline (2H9-Cho) for tumor characterization; however, they were performed at doses that exceeded severalfold the daily recommended Cho intake. Here, we investigated the feasibility of oral (PO) administration of 2H9-Cho with a dose set at the recommended upper limit for daily use in humans. DMI was performed in rats with orthotopic glioblastoma tumors following a single, high-dose IV bolus (1 x 285 mg/kg) or low-dose PO administration over three consecutive days (3 x 50 mg/kg). Despite a lower cumulative dose, PO administration resulted in comparable total deuterated Cho (2H9-tCho) concentrations in the tumor, and tumor-to-brain image contrast relative to IV administration. Additionally, 2H and 2D 1H-14N HSQC NMR analyses on excised tumor tissue revealed differences in metabolite contributions to the in vivo 2H9-tCho peak. PO administration led to increased contributions from Cho-derived molecules that were products of tumor metabolism, than during IV infusion of 2H9-Cho. These findings suggest that repeated low-dose PO 2H9- Cho administration can generate high, image contrast between tumor and normal brain, that is predominantly generated by tumor metabolism instead of merely Cho uptake. These results can advance the clinical translation of tCho-DMI as a noninvasive imaging tool for brain tumor characterization by demonstrating the feasibility of an oral intake approach using a clinically relevant dose. Given that Cho is already a widely used and well-tolerated nutritional supplement, oral Cho administration offers a practical, noninvasive alternative to IV infusion that could be conducted alongside regular MRI.

cancer biology↗