2683-P: Quantitative Blood Oxygen Level–Dependent (qBOLD) Magnetic Resonance Imaging (MRI) for Assessing Pancreatic β-Cell Function in Cystic Fibrosis (CF)

Introduction and Objective: Diabetes is a highly prevalent comorbidity of CF, characterized by progressive loss of β-cell function. Since glucose-stimulated insulin secretion is coupled to O2 consumption and qBOLD MRI is sensitive to O2 extraction from the blood, we tested qBOLD to quantify endocrine function after glucose stimulation in CF. Methods: After an 8-10 hour overnight fast, participants with CF (n=2) who had normal glucose tolerance per ADA guidelines and healthy controls (HC, n=3) received a 50% intravenous dextrose load (0.3 gm/kg) during MRI. Serum C-peptide was measured from -20 to 20 minutes after IV dextrose for all except HC1. qBOLD imaging was performed at 3T using a multiple gradient recalled echo sequence, dynamically acquired before and immediately after dextrose. Post-dextrose changes in T2* were computed relative to mean baseline T2* values over the entire pancreas (i.e., % ΔT2*). Results: CF had lower insulin secretion than HC (Fig1A). Participants with CF had a net negative qBOLD response (Fig1B) during the first 20 minutes of insulin secretion (ΔT2*AUC -69). HC had a net positive response (ΔT2*AUC 80). Conclusion: Larger negative changes in T2* in CF suggest increased O2 extraction despite lower glucose stimulated insulin secretion. qBOLD MRI appears to identify pancreatic metabolic abnormalities in CF compared to healthy controls and may provide early assessment of β-cell function in CF. Disclosure L. Staimez: None. A. Horner: None. D. Coker: None. C. Driggers: None. S. Hao: None. A. Stecenko: None. P. Vellanki: Consultant; Ended; Sanofi, RTI International. D.A. Reiter: None. Funding NIH NIDDK (P30DK125013, K01DK133669)