Computed diffusion-weighted MR imaging for visualization of pancreatic adenocarcinoma: Comparison with acquired diffusion-weighted imaging.

OBJECTIVE: To assess the feasibility of computed diffusion-weighted imaging (cDWI) in comparison with directly acquired DWI for visualizing pancreatic adenocarcinomas.

MATERIALS AND METHODS: Patients with pancreatic adenocarcinoma underwent DWI at b-values of 0, 1000 (DWI1000 ), 1500 (DWI1500 ) and 2000 (DWI2000 ) s/mm2 . From DWIs at b-values of 0 and 1000s/mm2 , we generated cDWIs at b-values of 1500 (cDWI1500 ) and 2000 (cDWI2000 ) s/mm2 . DWI findings of pancreatic adenocarcinomas (clear hyperintensity; hyperintensity with an unclear distal border; and isointensity), the image quality and the tumor to pancreas contrast ratio (CR) were compared between directly acquired DWI and cDWI.

RESULTS: Among the 63 included patients, clear hyperintense tumors were seen in 35 on DWI1000 , 50 on DWI1500 , 50 on cDWI1500 , 53 on DWI2000 and 44 on cDWI2000 . Incidence of clear hyperintense tumors was significantly higher on cDWI1500 than on DWI1000 (P=0.013). There was no significant difference in the incidence of clear hyperintense tumors between DWI1500 and cDWI1500 (P>0.999), but a lower incidence was seen on cDWI2000 than on DWI2000 (P=0.028). Image quality was lower on cDWI than on DWI at b-values of 1500 (P=0.002) and 2000s/mm2 (P<0.001). The tumor to distal pancreas CR was significantly higher on cDWI2000 than on cDWI1500 (P<0.001), and on cDWI1500 than on DWI1000 (P<0.001). The cDWI showed a significantly higher tumor to distal pancreas CR than DWI at b-values of 1500 (P=0.004) and 2000s/mm2 (P<0.001).

CONCLUSIONS: cDWI1500 generated from b-values of 0 and 1000s/mm2 should be considered more effective than DWI1000 and at least as effective as DWI1500 .