ABSTRACT
Objective To investigate the feasibility of b value threshold maps based on MRI diffusion weighted imaging ( DWI ) in the diagnosis of pancreatic adenocarcinoma .Methods The preoperative MRI DWI [ b value=0( b0 ) and 1000 ( b1000 ) s/mm2 ] data of 14 patients who were postoperatively histologically confirmed as pancreatic ductal adenocarcinoma from September 2016 to May 2015 admitted in Shanghai Changhai Hospital were retrospectively analyzed .The b value threshold maps were calculated .Computed DWI images at b value of 1500 s/mm2 ( cDWIb1500 ) was calculated based on the scanned DWI images of b 0 and b1000 s/mm2 . The efficacy of DWIb 1000 , b value threshold map and cDWIb 1500 in manifesting pancreatic adenocarcinoma was assessed by a four-point scale .The non-parametric Friedman test was used to compare the three methods , and Conover adjusted method was applied to compare any two of the three methods .Results The conspicuity score of DWIb 1000 , b value threshold map and cDWIb 1500 in showing pancreatic cancer was 2.9 ±0.8, 3.7 ±0.5 and 3.6 ±0.5, respectively, and the differences among the three methods were statistically significant (F=19.5, P value <0.001), but the differences on tumor conspicuity scores of b value threshold map and cDWIb 1500 were not statistically different .Conclusions The calculation of b value threshold map based on DWI images could show pancreatic cancer in high contrast quickly by adjusting window width and window level , and could achieve comparable performance as cDWIb 1500 .