Abstract： Objective To study the value of reduced field-of-view (rFOV DWI) in differentiating patients with solid pancreatic focal lesions.Methods 139 patients with solid pancreatic mass were enrolled,including 105 patients with pancreatic ductal acinar carcinoma (PDAC),16 patients with neuroendocrine neoplasms,7 patients with mass forming chronic pancreatitis (MFCP) and 11 patients with solid papillary tumor (SPT).38 healthy adult volunteers served as controls,and underwent single stimulated echo planar imaging (ss-EPI) DWI and rFOV DWI(b value =0 and 600 s/mm2) MRI examination.Quartation method was used to evaluate the image quality of ss-EPI) DWI and rFOV DWI in the three terms of the visibility of anatomical structure,contrast of pancreatic lesions,motion and the susceptibility artifacts during MRI.Work station self-carried software was used to measure the ADC value of the region of interest (ROI).The image quality and ADC values of different pancreatic diseases and normal pancreas were compared.ROC curve for ADC value was drawn to evaluate the difference among PDAC,other benign pancreatic masses and normal pancreas.Results At b value of 0 and 600 s/mm2,rFOV DWI was superior to ss-EPI DWI in terms of showing pancreatic anatomic structure,the contrast of the lesion and the score evaluation for susceptibility artifacts(b =0 s/mm22.99 ±0.51 vs 2.79 ±0.64,2.37±0.48 vs 1.81 ±0.63,3.17 ±0.56 vs 2.91 ±0.60;b =600 s/mm23.63 ±0.50 vs 3.32 ±0.56,3.45 ±0.50 vs 3.01 ±0.49,3.74 ±0.44 vs 3.12 ±0.37),and the differences were statistically significant (P＜0.001).ADC values of PDAC,NET,MFCP,SPT and normal pancreas were (1.38 ± 0.17) × 10-3,(1.22 ± 0.35) × 10-3,(1.29 ± 0.13) × 10-3,(1.04 ± 0.38) ×10-3and(1.86±0.15) ×10-3mm2/sforrFOV DWI,and (1.73 ± 0.24) ×10-3,(1.63±0.39) ×10-3,(1.58±0.19) × 10-3,(1.25±0.26) × 10-3 and(2.04±0.20) × 10-3mm2/s for ss-EPI DWI.The difference on ADC values among different groups and within one group were all statistically significant (P ＜0.001).There were no statistical significant differences on ADC values between MFCP and PDAC,between MFCP and SPT as well as on ss-EPI DWI ADC values between PDAC and NET,but statistical differences were found between other two groups (P ＜ 0.05).The area under the ROC curve of rFOV and ssEPI DWI was 0.983 (95％ CI 0.944-0.998) and 0.889 (95％ CI 0.822-0.936),respectively,and the difference was statistically significant (P =0.0004),but rFOV DWI and ss-EPI DWI ADC values for PDAC and all benign solid diseases were 0.799 (95％ CI 0.719-0.864) and 0.755 (95％ CI 0.672-0.827),and the difference was not statistically significant.Conclusions rFOV DWI could significantly enhance the quality of DWI images,and its diagnostic efficacy was much better than ss-EPI DWI.