Native T1 mapping of autoimmune pancreatitis as a quantitative outcome surrogate

Objectives To investigate the ability of T1 mapping to visualize and quantify the short-term and mid-term response of autoimmune pancreatitis (AIP) to corticosteroid treatment (CST) and to correlate T1 relaxation time of the pancreas with clinical status and serum IgG4 level. Methods The institutional review board approved this prospective study, and all patients provided written informed consent. Pancreatic MRI including native T1 mapping was performed in 39 AIP patients before and during CST, and 40 patients without pancreatic diseases served as control. T1 relaxation time of the pancreatic head, body, and tail was measured in each patient. Clinical symptoms and serum IgG4 level of the patients were recorded. Results The native T1 relaxation time of AIP was significantly elongated compared to normal pancreatic tissue (1124.5 ms ± 95.7 ms vs 784.3 ms ± 41.8 ms, p