Non‐invasive imaging of functional pancreatic islet beta‐cell mass in people with type 1 diabetes mellitus

Aims: To investigate whether manganese-enhanced
magnetic resonance imaging
can assess functional pancreatic beta-cell
mass in people with type 1 diabetes mellitus.
Methods: In a prospective case–control
study, 20 people with type 1 diabetes
mellitus (10 with low (≥50 pmol/L) and 10 with very low (concentrations) and 15 healthy volunteers underwent manganese-enhanced
magnetic resonance imaging of the pancreas following an oral glucose load. Scan-rescan
reproducibility was performed in 10 participants.
Results: Mean pancreatic manganese uptake was 31 ± 6 mL/100 g of tissue/min
in healthy volunteers (median 32 [interquartile range 23–36]
years, 6 women),
falling to 23 ± 4 and 13 ± 5 mL/100 g of tissue/min (p ≤ 0.002 for both) in people
with type1 diabetes mellitus (52 [44–61]
years, 6 women) and low or very low
plasma C-peptide
concentrations respectively. Pancreatic manganese uptake
correlated strongly with plasma C-peptide
concentrations in people with type1
diabetes mellitus (r = 0.73, p < 0.001) but not in healthy volunteers (r = −0.054,
p = 0.880). There were no statistically significant correlations between manganese
uptake and age, body-mass
index, or glycated haemoglobin. There was strong
intra-observer
(mean difference: 0.31 (limits of agreement −1.42 to 2.05) mL/100 g
of tissue/min; intra-class
correlation, ICC = 0.99), inter-observer
(−1.23 (−5.74 to
3.27) mL/100 g of tissue/min; ICC = 0.85) and scan-rescan
(−0.72 (−2.9 to 1.6)
mL/100 g of tissue/min; ICC = 0.96) agreement for pancreatic manganese uptake.
Conclusions: Manganese-enhanced
magnetic resonance imaging provides a potential
reproducible non-invasive
measure of functional beta-cell
mass in people with type
1 diabetes mellitus. This holds major promise for investigating type 1 diabetes, monitoring
disease progression and assessing novel immunomodulatory interventions.