Comparison of contrast-enhanced ultrasonography and magnetic resonance imaging in displaying anatomic features of cystic pancreatic masses

Purpose: To compare the accuracy of ultrasound (US), contrast-enhanced ultrasonography (CEUS) and Magnetic Resonance Imaging (MRI) in displaying anatomic features of cystic pancreatic masses greater than 1.5mm.

Materials and methods: US, CEUS and MRI examinations of 33 patients who underwent resection for a cystic pancreatic mass were retrospectly reviewed. Two radiologists, blinded to the final histologic diagnosis, reviewed the studies specifically assessing the presence of either intralesional mural nodules or septa. Sensitivity (Se), specificity (Sp), positive (PPV) and negative (NPV) predictive values and accuracy (Acc) were calculated based on correlation with surgical specimens. US, CEUS and MRI results were compared by McNemar test. The correlation of US and CEUS vs. pathology was established with Spearman's test. Interobserver variability was determined.

Results: CEUS correctly detected intralesional septa in 14/15 lesions (Acc of 90.9%) and nodules in 6/8 lesions (Acc of 90.9%). MRI correctly detected intralesional septa in 14/15 lesions (Acc of 75.7%) and nodules in 7/8 lesions (Acc of 81.8%). Difference in diagnostic accuracy between CEUS and MRI was not significant (p=0.05; McNemar Test) in the identification of septa and nodules. The correlation of CEUS vs. pathology was significantly superior (Rs=0.93; p<0.001) to that of US (Rs=0.52; p<0.0001). Interobserver agreement was k=0.86–0.94.

Conclusions: CEUS compares favourably with MRI in displaying anatomic features of cystic pancreatic masses seen at transabdominal US.