['Type 1 autoimmune pancreatitis (AIP) is clinically characterized by a response to steroid therapy. Despite having a favorable prognosis, AIP has a high relapse rate and factors predicting relapse in AIP patients treated with steroids have not yet been established.', 'A retrospective chart review was conducted of 32 newly diagnosed type 1 AIP patients who had undergone enhanced computed tomography (CT) pre- and post-steroid therapy.', 'Ten patients experienced relapse. Pancreatic volume was reduced significantly in all patients (pre-treatment volume, 88.5\u2009±\u200932.9\xa0cm(3) vs. post-treatment volume, 45.4\u2009±\u200921.1\xa0cm(3); P\u2009<\u20090.001), although the pre-treatment pancreatic volume did not differ between the relapse and non-relapse groups (92.6\u2009±\u200910.5\xa0cm(3) vs. 86.6\u2009±\u20097.1\xa0cm(3), P\u2009=\u20090.401). However, the post-treatment pancreatic volume was significantly greater in the relapse group than that in the non-relapse group (56.9\u2009±\u20096.3\xa0cm(3) vs. 40.2\u2009±\u20094.2\xa0cm(3), P\u2009=\u20090.008). Similarly, the percent reduction in pancreatic volume was significantly smaller in the relapse group than that in the non-relapse group (36.6\u2009±\u20094.7\xa0% vs. 52.1\u2009±\u20093.2\xa0%, P\u2009=\u20090.002). Multivariate analysis identified post-treatment pancreatic volume (HR, 1.04, 95\xa0% CI: 1.01-1.08, P\u2009=\u20090.010) and percent reduction in pancreatic volume (HR, 0.87, 95\xa0% CI: 0.79-0.94, P\u2009<\u20090.001) as predictive factors for relapse of type 1 AIP. A post-treatment pancreatic volume of 50\xa0cm(3)\u2009<\u2009(P\u2009=\u20090.009) and a percent reduction in the pancreatic volume of <35\xa0% (P\u2009=\u20090.004) had a significantly high relapse rate. These data suggest that early pancreatic volume changes after steroid therapy may be a useful prognostic value, because type 1 AIP patients with a high post-treatment pancreatic volume or low pancreatic volume reduction showed significant relapse.'] Does early pancreatic volume reduction on CT predict relapse in patients with type 1 autoimmune pancreatitis treated with steroids?