Pancreatic perfusion and its response to glucose as measured by simultaneous PET/MRI

Daniel Espes,Anneli Rydén,Marianne Jensen-Waern,Jan Weis,Lina Carlbom,Leif Jansson,Olof Eriksson,Elin Manell

doi:10.1007/s00592-019-01353-2

Abstract

AimsPerfusion of the pancreas and the islets of Langerhans is sensitive to physiological stimuli and is dysregulated in metabolic disease. Pancreatic perfusion can be assessed by both positron emission tomography (PET) and magnetic resonance imaging (MRI), but the methods have not been directly compared or benchmarked against the gold-standard microsphere technique.MethodsPigs (n = 4) were examined by [15O]H2O PET and intravoxel incoherent motion (IVIM) MRI technique simultaneously using a hybrid PET/MRI scanner. The pancreatic perfusion was measured both at basal conditions and after intravenous (IV) administration of up to 0.5 g/kg glucose.ResultsPancreatic perfusion increased by 35%, 157%, and 29% after IV 0.5 g/kg glucose compared to during basal conditions, as assessed by [15O]H2O PET, IVIM MRI, and microspheres, respectively. There was a correlation between pancreatic perfusion as assessed by [15O]H2O PET and IVIM MRI (r = 0.81, R2 = 0.65, p < 0.01). The absolute quantification of pancreatic perfusion (ml/min/g) by [15O]H2O PET was within a 15% error of margin of the microsphere technique.ConclusionPancreatic perfusion by [15O]H2O PET was in agreement with the microsphere technique assessment. The IVIM MRI method has the potential to replace [15O]H2O PET if the pancreatic perfusion is sufficiently large, but not when absolute quantitation is required.

Highlights

Between 10 and 20% of the total pancreatic blood flow in animals is diverted through the islets of Langerhans during basal physiological conditions, even though they only constitute 1–2% of the total pancreatic volume [1, 2]
Both the basal- and glucose-stimulated pancreatic perfusion were aberrantly regulated in individuals with obesity, type 1 diabetes (T1D), and type 2 diabetes (T2D) [6,7,8,9,10], but could be normalized by intervention
The baseline perfusion assessed by [15O]H2O positron emission tomography (PET) was 0.8 ml/min/g, which increased by 23% to 0.98 ml/ min/g after IV administration of 0.5 g/kg glucose

Summary

Introduction

Between 10 and 20% of the total pancreatic blood flow in animals is diverted through the islets of Langerhans during basal physiological conditions, even though they only constitute 1–2% of the total pancreatic volume [1, 2]. The positron emission tomography (PET) radiopharmaceutical [15O]H2O (Oxygen-15 isotopically labeled water) has enabled quantitative assessments of pancreatic perfusion in humans [6] Using this method, it was shown that an oral glucose challenge potentiated the pancreatic perfusion by up to 50% in healthy humans [6]. Both the basal- and glucose-stimulated pancreatic perfusion were aberrantly regulated in individuals with obesity, type 1 diabetes (T1D), and type 2 diabetes (T2D) [6,7,8,9,10], but could be normalized by intervention (such as bariatric surgery [11]) Both the preclinical and the clinical literature point to an important role of pancreatic perfusion defects in metabolic disease. The purpose of the current study was to directly compare MRI with [15O]H2O PET and the gold-standard microsphere technique for the assessment of pancreatic perfusion in pigs

Method and materials

Results

Discussion

Conclusion

Compliance with ethical standards