Prospective evaluation of nonenhanced MR imaging in acute pancreatitis

Abstract

To compare the value of nonenhanced (NE) magnetic resonance imaging (MRI) (NE-MRI) with contrast-enhanced (CE) computed tomography (CT) (CE-CT) scan in assessing acute pancreatitis (AP) and in evaluating the severity index (SI) with clinical outcome. Patients with AP were prospectively investigated by CE-CT scan and NE-MRI on admission. MRI was performed with fat-saturated T1-weighted imaging, T2-weighted imaging, and MR cholangiopancreatography (MRCP). Balthazar's grading system was used to evaluate the NE-MRI severity index (CTSI, MRISI) and it was compared to the clinical outcome. A total of 90 patients (median age = 55 years) were included in the study. AP was of biliary etiology in 37 patients (41%). On admission, AP was assessed as grade III by CTSI in four patients (4%), whereas 19 patients were classified grade III by MRISI. The coefficient correlation between CTSI and MRISI was good, with r = 0.6 (P < 0.001). Considering CE-CT scan as the gold standard, sensitivity (Sn), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of NE-MRI for detecting severe AP based on imaging criteria were 100%, 82.6%, 100%, and 21%, respectively. NE-MRI discriminates normal pancreatic parenchyma from edema and necrosis with a correlation between morbidity (P < 0.008). NE-MRI seems to be a reliable method of staging AP severity in comparison to CE-CT scan.