Assessment of Liver Metastases Using CT and MRI Scans in Patients with Pancreatic Ductal Adenocarcinoma: Effects of Observer Experience on Diagnostic Accuracy

To investigate the impact of radiologic experience on the diagnostic accuracy of computed tomography CT vs. magnetic resonance imaging (MRI) reporting for liver metastases of pancreatic ductal adenocarcinoma (LM of PDAC). Intra-individual CT and MRI examinations of 112 patients with clinically proven LM of PDAC were included. Four radiologists with varying years of experience (A > 20, B > 5, C > 1 and D < 1) assessed liver segments affected by LM of PDAC, as well as associated metastases occurring in each patient. Their sensitivity and specificity in evaluating the segments were compared. Cohen's Kappa (κ) for diagnosed liver segments and Intra-class Correlation Coefficients (ICC) for the number of metastatic lesions in each patient were calculated. The radiologists’ sensitivity and specificity for the CT vs. MRI were, respectively: Reader A -94.4, 90.3% vs. 96.6, 94.8%; B - 86.7, 79.7% vs. 83.9, 82.0%; C - 78.0, 76.7% vs. 83.3, 78.9% and D - 71.8, 79.2% vs. 64.0, 69.5%. Reviewers A and B achieved greater agreement in assessing results from the MRI (κ = 0.72, p < 0.001; ICC = 0.73, p < 0.001) vs. the CT (κ = 0.58, p < 0.001; ICC = 0.61, p < 0.001), in contrast to readers C and D (MRI: κ = 0.34, p < 0.001; ICC = 0.42, p < 0.001, and CT: κ = 0.48, p < 0.001; ICC = 0.59, p < 0.001). Our results indicate that accurate diagnosis of LM of PDAC depends more on radiologic experience in MRI over CT scans.