How Are Imaging Findings Associated with Exocrine Insufficiency in Idiopathic Chronic Pancreatitis?

Abstract

Aim The aim is to study the association between imaging findings in chronic pancreatitis and fecal elastase 1 (FE1) in patients with idiopathic chronic pancreatitis (ICP). Methods In this retrospective study on a prospectively maintained database of patients with ICP, a radiologist blinded to clinical and laboratory findings reviewed CT and/or MRI. Findings were documented according to recommendations of the Consortium for the Study of Chronic Pancreatitis, Diabetes, and Pancreatic Cancer, October 2018. Low FE1 (<100 μg elastase/g) was considered diagnostic of pancreatic exocrine insufficiency (PEI). Association between imaging findings and FE1 was studied. Results In total, 70 patients (M: F = 37:33) with ICP with mean age of 24.2 (SD 6.5) years, range 10 to 37 years and mean disease duration of 5.6 (SD 4.6) years, range 0 to 20 years were included. Mean FE level was 82.5 (SD 120.1), range 5 to 501 μg elastase/g. Mean main pancreatic duct (MPD) caliber was 7 (SD 4) mm, range 3 to 21 mm and mean pancreatic parenchymal thickness (PPT) was 13.7 (SD 5.5) mm, range 5 to 27 mm. There was a significant association between FE1 and MPD size, PPT, type of pancreatic calcification; presence of intraductal stones, side branch dilatation on magnetic resonance cholangiopancreatography and extent of pancreatic involvement ( p <0.05). In total, 79%, 86%, and 78% with moderate to severe MPD dilatation, pancreatic atrophy, and side branch dilatation had low FE1, respectively. But nearly half of those with no or mild structural abnormality on imaging had low FE1. Conclusion Significant association between FE1 and specific imaging findings demonstrates its potential as a marker of exocrine insufficiency and disease severity in chronic pancreatitis. But imaging and FE1 are complementary rather than supplementary.

Keywords: CT; MRI; chronic pancreatitis; fecal elastase 1; pancreatic exocrine insufficiency.

Fig. 1

Flowchart of patients included in the study.

Fig. 2

CT images showing examples of types of pancreatic parenchymal calcifications. ( A ) Diffuse fine punctate calcification. ( B ) Coarse calcification.

Fig. 3

MRCP images showing examples of main pancreatic duct (MPD) dilatation and contour. ( A ) Diffuse smooth dilatation of MPD. ( B ) Moderately dilated irregular MPD. ( C ) Severely dilated irregular beaded MPD. MRCP, magnetic resonance cholangiopancreatography.

Fig. 4

Technique of measuring parenchymal thickness in the mid body of pancreas. ( A ) Parenchymal thickness is measured in an axial CT section, perpendicular to the pancreatic parenchyma, at the lateral margin of adjacent vertebral body. ( B ) In patients with dilated main pancreatic duct, duct diameter is excluded from the measurement.

Fig. 5

( A ) MRCP and ( B, C ) T2-weighted axial MR images of a patient with main pancreatic duct stenosis at the head of pancreas. Note the severe dilatation of MPD distal to the level of stenosis. MRCP, magnetic resonance cholangiopancreatography.