Diagnostic performance of MRI and EUS in the differentiation of benign from malignant pancreatic cyst and cyst communication with the main duct

Purpose: To assess the diagnostic ability of MRI and EUS for differentiating benign from malignant pancreatic cyst focusing on cyst communication with pancreatic duct.

Materials and methods: During 44 months, we performed MRI on 65 pancreatic cysts. Among them, 36 patients had confirmed cyst communication with duct by ERCP or surgery and 39 patients underwent EUS. Fifty-one had proven by surgery or aspiration. Among them, 36 had confirmed malignant cysts. Two radiologists independently graded cyst communication with duct and the likelihood of malignancy. When the readers' interpretations differed, third opinion was obtained. They also measured the size of cyst and main duct. The diagnostic performance was analyzed using the ROC curve. The Mann-Whitney U test and κ statistics were used to determine interobserver agreement.

Results: The Az of MRI and EUS for determining diagnostic performance regarding the cyst communication with duct, were 0.931 and 0.930, without statistically difference (p=0.6). Interobserver agreement was excellent (κ=0.81) on MRI and substantial (κ=0.69) on EUS. The Az of MRI and EUS for assessing diagnostic performance to differentiate malignant from benign cyst, was 0.902 and 0.923, without statistically difference (p=0.587). Interobserver agreement was excellent (κ=0.81) on MRI and moderate (κ=0.47) on EUS. The mean cyst size (3.98 cm+2.74: 3.17 cm+1.26, p=0.327) and the duct size (5.20 mm+3.22: 4.39 mm+4.12, p=0.227) showed no statistically difference between malignant and benign cysts.

Conclusion: MRI and EUS can accurately assess pancreatic cyst communication with duct and are very useful for obtaining a differential diagnosis of malignant cyst versus benign pancreatic cyst.