ABSTRACT
Objective To investigate the role of DWI in differentiating autoimmune pancreatitis ( AIP) from pancreatic cancer ( PC) , and in the therapeutic effect evaluation of AIP.Methods DWI data of 26 cases with AIP , 29 cases with PC and 30 cases with normal pancreas ( NP ) were analyzed retrospectively.The distribution type and signal feature of lesions in cases with AIP or PC were evaluated by Chi-squared test.ADC values were measured and compared among 3 groups by Kruskal-Wallis test.ADC values of AIP and PC were analyzed by using ROC curve to determine the optimal threshold and diagnostic efficiency.ADC values were compared in AIP ( n=15 ) before and after steroid therapy by paired t test.Results Diffuse lesions were detected in 21 cases with AIP and 3 cases with PC, while focal lesions in 5 cases with AIP and 26 cases with PC (χ2 =27.64, P0.05).The median ADC values of AIP, PC and NP were 1.15 ×10 -3,1.35 × 10 -3 ,1.59 ×10-3 mm2/s, respectively; and the difference was statistically significant ( H=45.60, P <0.01).ROC analysis yielded an optimal ADC cutoff value of 1.255 ×10 -3 mm2/s (80.8% sensitivity, 79.3%specificity and 0.871 area under curve for the diagnosis of AIP ).ADC values of AIP ( n=15) were markedly increased from the baseline (1.10 ±0.19) ×10 -3 to (1.57 ±0.12) ×10 -3 mm2/s after steroid therapy (t=-10.14, P<0.01).Conclusions DWI may be useful for diagnosing and evaluating the effect of steroid therapy in AIP.ADC values of AIP were significantly lower than those of pancreatic cancer and normal pancreas.After steroid therapy , ADC values were markedly increased in AIP.
ABSTRACT
Objective To investigate magnetic resonance imaging(MRI) characteristics of autoimmune pancreatitis(AIP) in middle-aged and elderly patients. Methods MRI were performed in 17 middle-aged and elderly patients with AlP proved histopathologically or clinically. All clinical and MRI data were reviewed. Results Of 17 cases, MRI showed diffuse enlargement of the pancreas in 13 cases, and focal lesions in 4 cases. Swelled pancreas was hypointense on T1-weighted images, mildly hyperintense on T2-weighted images, decreased enhancement on artery phase of dynamic imaging, and moderate enhancement on delayed phase images. Capsule-like enhanced rim was found around swelled pancreas in 13 patients. Stricture of distal common bile duct was present in 15 patients, and diffuse irregular narrowing of the main pancreatic duct was showed in 5 cases. The mean apparent diffusion coefficient(ADC) value of AIP was 1.64×10~(-3) mm~2/s in 13 cases. Conclusions AIP occurs more often in middle-aged and elderly people. AIP shows some characterized MRI findings including swelled pancreas looking like banana or sausage, delayed enhanced capsule-like rim around the lesion and diffuse irregular narrowing of pancreatic duct. MRI will play an important role not only in the diagnosis of AIP, but also in evaluating curative effect of AIP.