T 1 mapping for diagnosis of mild chronic pancreatitis.

PurposeTo determine if the T-1 relaxation time of the pancreas can detect parenchymal changes in mild chronic pancreatitis (CP). Materials and MethodsThis 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. ResultsThere 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 (=0.33, P=0.01) in the control group, but not in the mild CP group. ConclusionThe 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.