| Objective①To investigate the value of non-enhanced MRI imaging sequences included T2-weighted,Tl-weighted and MR cholangiopancreatography(MRCP) for the clinical classification of chronic pancreatitis based on MANNHEIM system on 1.5T MR System;②To investigate the value of dynamic enhanced MRI imaging sequences for the clinical classification of chronic pancreatitis;③To investigate the value of DWI(diffusion-weighted imaging) for the clinical classification of chronic pancreatitisMethods 65 patients with confirmed chronic pancreatitis(14 mild,37 moderate and 14 severe with MANNHEIM system) and 20 healthy volunteers were included in this study. MR examination including the routine abdomen scanning protocol, enhanced MRI and DWI was performed for both patients and volunteers. The axial fat-suppressed volume interpolated body examination (VIBE)was used for T1-weighted and the dynamic enhanced MRI; The axial fat-suppressed trubo spin echo(TSE) sequence was used for T2-weighted; Diffusion-weighed MR imaging was performed with the echo planar imaging(EPI) sequence and the b values of 200,400,and 600 s/ mm2 were selected to acquire the DWI and the corresponding apparent diffusion coefficient (ADC). MR cholangiopancreatography(MRCP) was performed with the HASTE technique. Then data were measured and statistical analysis was applied in four groups. A single radiologist assessed Cambridge classification, pancreatic duct diameter, pancreatic size, pancreatic cyst, pancreatic stone and pancreatic signal intensity (SI)at head, body and tail of the pancreas on MRCP, T1-weighted and T2-weighted images. Pancreatic signal intensity in different enhanced phases and ADCs were also measured on dynamic enhanced MR and DW-MR images.Results①Mean values of pancreatic signal intensity ratio(SIR) on T1 WI in the pancreas were significantly reduced in patients with moderate and severe CP compared with volunteers.There was significant difference among four groups(normal, 0.98±0.27;mild,0.84±0.12;moderate,0.81±0.16;severe,0.75±0.24). Mean values of pancreatic signal intensity ratio on T2WI in the pancreas were increased in patients with severe CP compared with volunteers.There was no difference among four groups(normal,1.28±0.30; mild,1.46±0.44, moderate,1.46±0.55; severe,1.75±0.72). Pancreatic duct diameters were significantly increased in mild,moderate and severe CP groups (mild5.33±2.44;moderate 6.48±3.3; severe 8.05±4.14)compared with patients without CP (1.96±0.58; p<0.01). Severe degree of Cambrige classification was increased in moderate and severe CP groups compared with mild group.Pancreatic calcification was graded as mild in 2 (2/14,14%),moderate in 11(11/37,30%),severe in 5(5/14,71%). Pancreatic pseudocyst was graded as mild in 0(0/14),moderate in 5(5/37, 13%),severe in 3 (3/14,36%). Pancreatic parenchymal atrophy was present in 36 patients and was graded as mild in 4 (4/14,28%),moderate in 22 (22/37,60%),severe in 10 (10/14,71%).The presence of pancreatic calcifications,pseudocyst and pancreatic parenchymal atrophy did not vary among cp groups.②Arterial/parenchymal phase enhanced ratio (A/P) in the pancreas were significantly reduced in patients with mild,moderate and severe CP (mild, 0.973±0.797; moderate,0.960±0.119; severe,0.888±0.111)compared with patients without CP (1.805±0.175, p< 0.01)③Apparent diffusion coefficients(ADCs) in the pancreas din't not vary among four groups (control group,1.430±0.520;mild CP,1.291±0.251; moderate CP, 1.420±0.385; severe CP,1.432±0.509; P>0.05)under b values of 200 and 600s/mm2. There was also no difference between pancreatic dysfunction group and normal function group.Conclusion Significant correlation is present between the Severity level of CP and the pancreatic duct diameter,the presence of pancreatic parenchymal atrophy.,the change of pancreatic signal intensity ratio on T1 WI and arterial/parenchymal phase enhanced ratio (A/P). T1-weighted,MRCP and dynamic enhanced MRI imaging can accurately evaluate the clinical severity of chornic pancreatitis,while T2-weighted and DW-MR images may be less useful...
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