Combination of secretin-enhanced MR cholangiopancreatography and conventional MRI in the diagnosis of chronic pancreatitis

Objective To discuss the value of combining secretin-enhanced MR cholangiopancreatography (MRCP) and conventional MRI in the evaluation of chronic pancreatitis (CP).Methods Seventeen normal volunteers,and 36 patients with CP were enrolled in this study.Thick slab two dimension MRCP sequence,coronal T2 weighted sequence and conventional MRI were performed on all subjects.The changes of pancreatic ducts were observed before and after the injection of secretin.The exocrine function of the pancreas was evaluated using duodenal filling (DF) grades.Pancreatic parenchyma was reflected by signal intensity ratio (SIR) between the pancreas and the left psoas muscle on MR plain scan,and the ratio between the pancreatic substance phase and portal phase (A/V) of MR enhanced scan.All subjects were classified based on Cambridge classification and DF grades.The SIR and A/V were compared between all groups of Cambridge classification using the one-way ANOVA test,and between two groups of DF grades using Student's t test.Correlations between Cambridge classifications,DF grades and SIR,A/V were tested using Spearman rank correlation coefficients.Results After secretin injection,the visualization of all portions of the main pancreatic ducts and branch ducts were significantly improved in all subjects.Ten minutes after secretin injection,17 volunteers showed grade 3.Grade 3,2 and 1 were seen in 23,8,5 patients,respectively.Mild,moderate and severe CP by Cambridge classification showed in 11,12,13 patients,respectively.The mean SIR values of the volunteers and the three groups were 1.21 ± 0.19,1.07 ±0.21,0.98 ± 0.21 and 0.85 ± 0.18,respectively; the mean A/V values:1.15 ± 0.11,1.23 ± 0.34,0.97 ± 0.16 and 0.91 ± 0.12.There was statistically significant difference of SIR and A/V (F =8.72 and 7.72,P ＜0.01) between volunteers and CP.Normal and abnormal DF were seen in 40 and 13 patients.The mean SIR values of the two groups were 1.09 ± 0.20 and 0.88 ± 0.27 ; the mean A/V values:1.15 ± 0.11 and 0.94 ± 0.30.There was statistically significant difference of SIR and A/V (t =3.10 and -2.40,P ＜ 0.01) between two groups.There were correlations between Cambridge classification,DF grades and SIR (r =0.60 and 0.41,P＜0.01),A/V (r =0.60 and 0.52,P＜0.01).Conclusion Secretin-enhanced MRCP combined with conventional MRI can be used to evaluate CP regarding changes of morphology and function,which can provide a useful reference for the clinical diagnosis. Key words: Pancreatitis,chronic;  Magnetic resonance imaging;  Comparative study