Revised Atlanta classification for CT pancreatic and peripancreatic collections in the first month of acute pancreatitis: interobserver agreement.

PURPOSE: To assess interobserver agreement when using the revised Atlanta classification (RAC) to categorize pancreatic and peripancreatic collections during the first month of acute pancreatitis (AP), and to correlate type of collection to outcome.
MATERIAL AND METHODS: This retrospective study of 115 consecutive patients admitted for 123 AP episodes, 178 CTs performed within the first month showed peripancreatic abnormalities. Each AP episode was classified as mild, moderately severe, or severe based on the RAC. Two radiologists, blinded to clinical data, used RAC criteria to retrospectively categorize the collections as acute peripancreatic fluid collections (APFC) or acute necrotic collections (ANC). Interobserver agreement was assessed based on Cohen's κ statistics and compared according to CT timing.
RESULTS: Interobserver agreement for categorizing peripancreatic collections was moderate (κ = 0.45) and did not improve with time to CT (κ values, 0.53 < day 3, 0.34 on days 3-6, and 0.43 ≥ day 7). For detecting parenchymal necrosis, interobserver agreement was also moderate (κ = 0.45). AP was less severe in patients with APFC versus ANC (p = 0.04).
CONCLUSION: Our finding of moderate interobserver agreement when using the RAC to categorize pancreatic and peripancreatic collections by CT indicates that the accurate diagnosis of APFC or ANC by CT in the first 4 weeks after symptom onset is often challenging. KEY POINTS: • Interobserver agreement was moderate for categorizing peripancreatic collections. • Interobserver agreement did not improve with time from onset to CT. • Interobserver agreement was moderate for detecting parenchymal necrosis.