Cross-Modality Differences In Pancreatic Cyst Size Measurements May Affect Surgical Decision-Making

IntroductionAccurate preoperative measurement of pancreatic cystic lesions is critical for surgical decision-making, particularly around the 3 cm threshold frequently cited in resection guidelines. However, imaging modalities may provide discrepant size estimates, potentially altering management.MethodsWe retrospectively reviewed patients from a single endoscopist practice (November 2011-November 2024) who underwent EUS-FNA for pancreatic cystic lesions with available MRI and/or CT imaging results. For each modality, the largest recorded dimension was extracted. One-way ANOVA was performed to assess mean size differences, and concordance across the 3 cm surgical threshold was calculated with Cohen's κ.ResultsA total of 190 patients with 246 patient encounters were included. Mean cyst size was 2.93 ± 1.32 cm on MRI (n = 147), 2.95 ± 1.53 cm on EUS (n = 246), and 3.20 ± 1.73 cm on CT (n = 159). The differences were not statistically significant (P = .194). Across modalities, the mean absolute difference in size ranged from 0.7 to 0.9 cm, with outliers exceeding 2 cm. Concordance at the 3 cm cutoff was common; there was good agreement between EUS and MRI (κ = 0.643; P < .001) and moderate agreement between EUS and CT (κ = 0.472; P < .001).ConclusionSubstantial variability exists in preoperative size assessment of pancreatic cystic lesions, with 7.5-20% of cysts misclassified around the 3 cm cutoff. Given that cyst size is a key determinant of surgical intervention, reliance on a single modality may introduce bias into clinical decision-making. Multimodality assessment reduces discordance and may improve risk stratification.