An MPCR Study Of Correlation Between The Morphological Changes Of Main Pancreatic Ducts And Acute Pancreatitis

Objectives: To explore the correlation between the morphological changes of main pancreatic duct and acute pancreatitis by means of high field magnetic resonance cholangiopancreatography(MRCP) and image postprocessing techniques.Methods:1. 192 cases, who were administered with MRI and Two-dimension MRCP between December, 2012 and June 2014, were randomly collected. According to the inclusion criteria and exclusion criteria, 64 cases were finally chosen and then divided into Group A and Group B. The former consisted of 31 cases with acute pancreatitis; the latter, the normal control group, consisted of 33 cases.2. Type Discovery MR750 of GE 3.0T superconductive MRI scanner and 32 channels body phased array coils were used in the examination, before which abrosia and no fluid for 6-8 hours was required. Supine position and first feet were taken and xiphoid process was aligned with the center of coils. Respiratory gate was put on the maximum abdominal respiratory amplitude. Routine abdominal scan was conducted at breath-holding state of eupnea as follows: Abdominal axial T1-weighted imaging fast spoiled gradient echo sequence(T1WI FSPGR), T2-weighted imaging single shot fast spin echo sequence(T2WI SSFSE) and T2-weighted imaging fast recovery FSE with saturated fat suppression sequence(T2WI FRFSE FS) and Coronal T2 weighted single shot fast spin echo sequence(T2WI SSFSE). Single shot fast spin echo and 2D Thick slab sequence(2D Thick slab SSFSE fs) was used inMPCP. From the T2 WI saturated fat suppression sequence was selected an axial image for the location: centering on the lower part of common bile duct(the duodenal wall section), taking longitudinal sections at the interval of 15°, radially arranging them with the total of 9-15 frames. One of the sections was regarded as the standard coronary longitudinal section; scanning layers at the breath-holding state of eupnea were determined according to the length of breath-holding and this would continue until the scanning was finished. Scanning parameters included TR 2812~4512.5ms, TE 851.2~1256ms, field 36cm×36cm, matrix 384×512, slice thickness 40 mm, single scanning time 3s and the whole scanning time 31s~86s.3. Data of the two groups were respectively transmitted into the Image post-processing station. One clearest and complete MRCP image of the main pancreatic duct was chosen from the PACS system; the curve length and diameters of the duct and the linear distance between its head and tail were measured for three times respectively by two imaging diagnosticians by means of image post-processing software and the average value for each was the final value. The degree of flexion of the main pancreatic duct was the absolute value of the difference of the curve length and the linear head-and-tail distance. When big differences appeared, the diagnosticians would discuss, reach an agreement and determine the average as the final value. Paired T-test was adopted to analyze the inter-group consistency of data measured by the two diagnosticians. Independent t-test was used to analyze the data of Group A and Group B and receiver operating characteristic curve(ROC) was drawn to assess the diagnostic effects of the degree of flexion and curve length of the main pancreatic duct on acute pancreatitis.Results:1. The curve length, the linear head-and-tail distance and the flexion degree of the main pancreatic duct in Group A and Group B were 23.74±6.62(cm) and 17.24±3.35(cm), 11.46±1.73(cm) and 11.04±1.41(cm),12.28±5.54(cm) and 6.20±3.46(cm), respectively. Statistical significance existed in the flexion degree and curve length of the main pancreatic duct between the two groups(P=0.009, P=0.001, respectively); no statistical significance was found in the linear head-and-tail distance of the main pancreatic duct between the two groups(P=0.240).2. The diameters of the head, body and tail of the main pancreatic duct in Group A were 2.69±0.43 mm, 2.12±0.40 mm and 1.52±0.23 mm, respectively and those in Group B were 2.55±0.43 mm, 2.05±0.33 mm and 1.38±0.25 mm, respectively. No statistical significance was found between the two groups(p>0.05).Conclusions: There exists a correlation between the morphological changes of the main pancreatic duct(the flexion degree and curve length) and acute pancreatitis. The bigger the flexion degree is, the longer the curved path is, and the higher prevalence of acute pancreatitis will become.