Inter-observar concordance, correlation and signal intensity measurement of non-contrast magnetic resonance for the diagnosis of pancreatic necrosis

Abstract

Introduction: contrast MRI is considered an alternate exam for the diagnosis and classification of the severity of pancreatitis, and has shown better performance that contrast CT. It has been described for cases in which non-contrast MRI is also a reliable modality. Objective: to estimate the inter-observer concordance for the diagnosis of pancreatic necrosis using the T1 MRI sequence without contrast; correlate the MRI vs. the contrast CT data; measure the signal intensity of the necrotic parenchyma. Methodology: concordance and correlation trial. 110 cases with a suspected diagnosis of pancreatitis were distributed with random codes and differentiated by categories. 2 sub-specialist radiologists with 4 and 8 years of experience respectively participated. The presence, percentage severity, and the localization of necrosis were established in the T1 FS sequence. The Kappa coefficient and the tetrachoric correlation were used. Results: the inter-observer global kappa was 0,54 (95 % CI: 0,38 – 0,70), the agreement for necrosis free category was 65.96 %, for the 30-50 % category was 33,33 % and for the >50 % category was 86,67 %. The CT correlation was rho=0,73 (EE 0.10). The mean signal intensity in the necrotic foci was 69,61 (range 14 - 157) and in the parenchyma was 161,79 (range 101-273) (pp<0,05). Discussion: the level of agreement for the determination and classification of subjective necrosis in T1 was moderate, with a positive correlation between the CT and the non-contrast MRI. An objective difference was shown in the signal intensity of the necrotic parenchyma.