T₁ mapping for diagnosis of mild chronic pancreatitis

Purpose To determine if the T 1 relaxation time of the pancreas can detect parenchymal changes in mild chronic pancreatitis (CP). Materials and Methods This Institutional Review Board (IRB)‐approved, Health Insurance Portability and Accountability Act (HIPAA)‐compliant retrospective study analyzed 98 patients with suspected mild CP. Patients were grouped as normal ( n = 53) or mild CP ( n = 45) based on history, presenting symptomatology, and concordant findings on both the secretin‐enhanced magnetic resonance cholangiopancreatography (S‐MRCP) and endoscopic retrograde cholangiopancreatography (ERCP). T 1 maps were obtained in all patients using the same 3D gradient echo technique on the same 3T scanner. T 1 relaxation times, fat signal fraction (FSF), and anterior–posterior (AP) diameter were correlated with the clinical diagnosis of CP. Results There was a significant difference ( P < 0.0001) in the T 1 relaxation times between the control (mean = 797 msec, 95% confidence interval [CI]: 730, 865) and mild CP group (mean = 1099 msec, 95% CI: 1032, 1166). A T 1 relaxation time threshold value of 900 msec was 80% sensitive (95% CI: 65, 90) and 69% specific (95% CI: 56, 82) for the diagnosis of mild CP (area under the curve [AUC]: 0.81). Multiple regression analysis showed that T 1 relaxation time was the only statistically significant variable correlating with the diagnosis of CP ( P < 0.0001). T 1 relaxation times showed a weak positive correlation with the pancreatic FSF (ρ = 0.33, P = 0.01) in the control group, but not in the mild CP group. Conclusion The T 1 relaxation time of the pancreatic parenchyma was significantly increased in patients with mild CP. Therefore, T 1 mapping might be used as a practical quantitative imaging technique for the evaluation of suspected mild CP. Level of Evidence: 3 J. Magn. Reson. Imaging 2017;45:1171–1176