91-OR: Imaging β-Cell Response to Oral Glucose Stimulation with Quantitative Blood Oxygenation Dependent (qBOLD) MRI

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Introduction and Objective: The failure of pancreatic β-cells is a central feature of diabetes, yet measures of β-cell function in humans, such as clamp-derived variables, are invasive and sensitive to other factors (i.e., insulin resistance, insulin clearance, etc.). Since glucose-stimulated insulin release is coupled to pancreas oxygen consumption, we tested qBOLD MRI as a non-invasive proxy of spatiotemporal β-cell function during oral glucose-stimulated insulin secretion. Methods: Adults (age >18 years) were included across two groups: type 2 diabetes (T2D, n=4; BMI >30kg/m2; within 5 years of diagnosis) and healthy controls. (HC, n=6). Participants had a 75-gram oral glucose (OG) load and simultaneous qBOLD MRI of pancreas volume at fasting and up to 15 minutes post load. Dynamic change in MRI parameter, ΔT2*, was quantified across glucose ingestion, and mean (SD) post-glucose ΔT2* values were compared between groups. The T2D group had an additional OG load (separate day) within 2 weeks prior/after MRI, and C-peptides across 240 minutes (AUC) were correlated (Pearson r) with AUC ΔT2* for T2D. Results: Post-glucose ΔT2* values decreased (i.e. negative ΔT2*) consistent with increased oxygen consumption during β-cell insulin secretion (T2D -14.7 (7.4) % and HC -5.3 (7.7) %). ΔT2* AUC decreases (0-15min) were larger in T2D than HC (-17.1 (8.20) vs. -0.76 (1.04); p=.001). There was a strong positive correlation between C-peptide AUC (0-20min) and ΔT2* AUC (0-15min) in T2D patients (r =.95, p=.05), suggesting a relationship between MRI-derived β-cell metabolic activity and β-cell secretory activity. Conclusion: Initial quantification of dynamic T2* values over the entire pancreas using OG qBOLD MRI shows group differences and sensitivity to β-cell function. OG qBOLD demonstrates spatial and temporal heterogeneity of ΔT2* after glucose ingestion, holding potential to assess regional and temporal changes in pancreas function with disease severity. Disclosure D.A. Reiter: None. E. Ray: None. A. Horner: None. S. Edwards: None. O. Oladejo: None. P. Vellanki: Advisory Panel; Eli Lilly and Company. Funding National Institutes of Health (DK129627)

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