Inter-observer variability of radiologists for Cambridge classification of chronic pancreatitis using CT and MRCP: results from a large multi-center study

Abstract

Purpose: Determine inter-observer variability among radiologists in assigning Cambridge Classification (CC) of chronic pancreatitis (CP) based on magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) and contrast-enhanced CT (CECT).

Methods: Among 422 eligible subjects enrolled into the PROCEED study between 6/2017 and 8/2018, 39 were selected randomly for this study (chronic abdominal pain (n = 8; CC of 0), suspected CP (n = 22; CC of 0, 1 or 2) or definite CP (n = 9; CC of 3 or 4). Each imaging was scored by the local radiologist (LRs) and three of five central radiologists (CRs) at other consortium sites. The CRs were blinded to clinical data and site information of the participants. We compared the CC score assigned by the LR with the consensus CC score assigned by the CRs. The weighted kappa statistic (K) was used to estimate the inter-observer agreement.

Results: For the majority of subjects (34/39), the group assignment by LR agreed with the consensus composite CT/MRCP score by the CRs (concordance ranging from 75 to 89% depending on cohort group). There was moderate agreement (63% and 67% agreed, respectively) between CRs and LRs in both the CT score (weighted Kappa [95% CI] = 0.56 [0.34, 0.78]; p-value = 0.57) and the MR score (weighted Kappa [95% CI] = 0.68 [0.49, 0.86]; p-value = 0.72). The composite CT/MR score showed moderate agreement (weighted Kappa [95% CI] = 0.62 [0.43, 0.81]; p-value = 0.80).

Conclusion: There is a high degree of concordance among radiologists for assignment of CC using MRI and CT.

Keywords: Chronic pancreatitis; Computerized tomography; Inter-observer variability; Magnetic resonance cholangiopancreatography.

Figure 1.

2D thick-slab MRCP image (a) obtained 2 minutes after secretin administration demonstrates smooth contour of a prominent main pancreatic duct, which is tortuous (white arrow) in the region of pancreatic body. Note 2 abnormal branch ducts in the pancreatic head/neck (arrowheads). An axial image (b) from contrast-enhanced CT scan of the same patient demonstrates the prominent and slightly tortuous pancreatic duct (white arrows) in the body of pancreas. The apparent contour irregularity of PD from the tortuosity likely resulted in 2 of the 3 CRs categorizing the CT as grade 3 per CC with composite CT/MR score of 3, discordant from the corresponding composite CT/MR score of 1 by the LR.

Figure 1.

2D thick-slab MRCP image (a) obtained 2 minutes after secretin administration demonstrates smooth contour of a prominent main pancreatic duct, which is tortuous (white arrow) in the region of pancreatic body. Note 2 abnormal branch ducts in the pancreatic head/neck (arrowheads). An axial image (b) from contrast-enhanced CT scan of the same patient demonstrates the prominent and slightly tortuous pancreatic duct (white arrows) in the body of pancreas. The apparent contour irregularity of PD from the tortuosity likely resulted in 2 of the 3 CRs categorizing the CT as grade 3 per CC with composite CT/MR score of 3, discordant from the corresponding composite CT/MR score of 1 by the LR.