Definition of age-dependent reference values for the diameter of the common bile duct and pancreatic duct on MRCP: a population-based, cross-sectional cohort study.

OBJECTIVE: Changes of the pancreaticobiliary ducts herald disease. Magnetic resonance cholangiopancreatography (MRCP) allows accurate duct visualisation. Data on reliable upper reference ranges are missing. DESIGN: Cross-sectional whole body MRI data from the population-based Study of Health in Pomerania were analysed. The width of the common bile duct (CBD) and the pancreatic duct (PD) was determined. We aimed to describe the distribution of physiological duct diameters on MRCP in a population of healthy subjects and to identify factors influencing duct size. RESULTS: After excluding pre-existing pancreaticobiliary conditions, CBD and PD diameters from 938 and 774 healthy individuals, respectively, showed a significant increase with age (p<0.0001) and exceeded the conventional upper reference limit of normal in 10.9% and 18.2%, respectively. Age-dependent upper reference limits of duct diameters were delineated with non-parametric quantile regression, defined as 95th percentile: for CBD up to 8 mm in subjects <65 years and up to 11 mm in subjects ≥65 years. For the PD reference diameters were up to 3 mm in subjects <65 years and up to 4 mm in subjects ≥65 years. CONCLUSIONS: This is the first population-based study delineating age-adjusted upper reference limits of CBD and PD on MRCP. We showed that up to 18.2% of healthy volunteers would have needed diagnostic workup, if the conventional reference values were used. The utilisation of the adapted reference levels may help to avoid unnecessary investigations and thus to reduce healthcare expenditure and test-related adverse events.

Anatomic variants of the pancreatic duct and their clinical relevance: an MR-guided study in the general population.

OBJECTIVES: To investigate the frequency of pancreatic duct (PD) variants and their effect on pancreatic exocrine function in a population-based study using non-invasive secretin-stimulated magnetic resonance cholangiopancreatography (sMRCP). METHODS: Nine hundred and ninety-five volunteers, 457 women and 538 men, aged 51.9 ± 13.4 years, underwent navigator-triggered, T2-weighted, 3D turbo spin echo MRCP on a 1.5 T system after 1 unit/kg secretin administration. Two readers evaluated images for PD variants. Pancreatic exocrine function and morphological signs of chronic pancreatitis such as abnormalities of the main PD, side branch dilatation, and pancreatic cysts were evaluated and related to PD variants using a Kruskal-Wallis test and post hoc analysis. RESULTS: Of all sMRCP, 93.2% were of diagnostic quality. Interobserver reliability for detection of PD variants was found to be kappa 0.752 (95 %CI, 0.733 - 0.771). Normal PD variants were observed in 90.4% (n = 838/927). Variants of pancreas divisum was identified in 9.6% (n = 89/927). Abnormalities of the main PD, side branch dilatation, and pancreatic cysts were observed in 2.4%, 16.6%, and 27.7%, respectively, and were not significantly different between pancreas divisum and non-divisum group (P = 0.122; P = 0.152; P = 0.741). There was no association between PD variants and pancreatic exocrine function (P = 0.367). CONCLUSION: PD variants including pancreas divisum are not associated with morphological signs of chronic pancreatitis or restriction of pancreatic exocrine function. KEY POINTS: MRCP allows the evaluation of pancreatic duct variants and morphological change. Pancreatic duct variants are not associated with morphological signs of chronic pancreatitis. Pancreas divisum is not accompanied by restriction of pancreatic exocrine function. Pancreatic duct variants including pancreas divisum are limited in their clinical relevance.