Pancreatic iron and fat assessment by MRI-R2∗ in patients with iron overload diseases

Background To determine the pancreatic iron (R2) and fat content (FC) in comparison to hepatic and cardiac R2∗ in patients with iron overload disorders like β-thalassemia major (TM), Diamond-Blackfan anemia (DBA) or hereditary hemochromatosis. Methods R2∗ rates were assessed in the liver, heart and pancreas of 42 patients with TM, 29 subjects with other iron overload diseases, and 10 controls using an ECG-gated breathhold sequence (12 echo time [TE]=1.3-25.7 ms, readout repetition time [TR]=244 ms). Pancreatic R2∗ and FC were assessed from TE dependent region of interest based signal intensities performing water-fat chemical shift relaxometry and were compared with laboratory parameters (glucose, HbA1c, amylase and lipase). Results A pancreatic iron gradient from tail (R2=122 s^-1) to head (R2=114 s^-1, P<10^-4) was found. The close association between cardiac and pancreatic R2∗ was also confirmed in patients with TM and other iron overload diseases (r_s=0.64, P<10^-4). Receiver operator characteristic analysis (area: 0.89, P<10^-4) identified patients with elevated cardiac iron at a pancreatic R2∗ cut-off level of 131s^-1 (sensitivity=specificity at 81%). Highest pancreatic R2∗ (211s^-1) and FC (36%) were found in the tail region of diabetic patients with TM. Conclusion Pancreatic tail showed highest R2∗ rates and fat contents, especially in patients with thalassemia. Besides iron accumulation fatty degeneration might be an additional risk factor for the development of diabetes in β-thalassemia major, but this hypothesis needs further studies in prediabetic patients.