Pancreatic perfusion modulation following glucose stimulation assessed by noninvasive arterial spin labeling (ASL) MRI

Abstract

Background: More than 100 million adults in the US suffer from prediabetes or type-2 diabetes. Noninvasive imaging of pancreas endocrine function might provide a surrogate marker of β-cell functional integrity loss linked to this disease.

Purpose: To noninvasively assess pancreatic blood-flow modulation following a glucose challenge using arterial spin labeling (ASL) MRI.

Study type: Prospective.

Subjects: Fourteen adults (30 ± 7 years old, 3M/11F, body mass index [BMI] = 24 ± 3 kg.m^-2 ).

Field strength/sequence: 3T MRI / background-suppressed pseudocontinuous PCASL preparation with single-shot fast-spin-echo (FSE) readout before and after an oral glucose challenge using either fruit juice (n = 7) or over-the-counter glucose gel (n = 7).

Assessment: Subjects were fasting prior to initiation of oral stimulation, then dynamic perfusion measurements were performed every 2 minutes for 30 minutes. We quantified absolute blood flow at each timepoint.

Statistical tests: Repeated-measures analysis of variance (ANOVA) followed by paired t-tests to assess for a significant effect of glucose challenge on measured perfusion.

Results: Measured basal blood flow was 187 ± 53 mL/100g/min. A significant blood flow increase of +38 ± 26% was observed 10 minutes poststimulation (P < 0.05) and continuing until the end of the experiment. The gel stimulation provided the most consistent results, with an early rise followed by an additional later increase consistent with the known pancreatic insulin response to elevated blood glucose. Across-subject variations in blood flow increase were partially attributable to basal flow, with a negative correlation of r = -0.84 between basal and maximal relative flow increase in the gel group.

Data conclusion: ASL can be used to measure pancreatic flow in response to a glucose challenge, which could be linked to insulin release and secretion. This paradigm might be useful to characterize disorders of glucose regulation.

Level of evidence: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;51:854-860.

Keywords: ASL; endocrine function; glucose; pancreas; perfusion.