Objectives
To determine the optimal b-value of 3.0-T diffusion-weighted imaging (DWI) for visualizing pancreatic adenocarcinomas
Methods
Fifty-five patients with histologically confirmed pancreatic adenocarcinoma underwent DWI with different b-values (b = 500, 1000, 1500, and 2000 s/mm2) at 3.0 T. For each b-value, we retrospectively evaluated DWI findings of pancreatic adenocarcinomas (clear hyperintensity relative to the surrounding pancreas, hyperintensity with an unclear distal border, and isointensity) and image quality, and measured tumour-to-pancreas signal intensity (SI) ratios. DWI findings, image quality, and tumour-to-pancreas SI ratios were compared between the four b-values.
Results
There was a significantly higher incidence of tumours showing clear hyperintensity on DWI with b-value of 1500 s/mm2 than on that with b-value of 1000 s/mm2 (P < 0.001), and on DWI with b-value of 1000 s/mm2 than on that with b-value of 500 s/mm2 (P < 0.001). The tumour-to-distal pancreas SI ratio was higher with b-value of 1500 s/mm2 than with b-value of 1000 s/mm2 (P < 0.001), and with b-value of 1000 s/mm2 than with b-value of 500 s/mm2 (P < 0.001). A lower image quality was obtained at increasing b-values (P < 0.001); the lowest scores were observed with b-value of 2000 s/mm2.
Conclusions
The use of b = 1500 s/mm2 for 3.0-T DWI can improve the delineation of pancreatic adenocarcinomas.
Key Points • Diffusion-weighted imaging (DWI) has been used for diagnosing pancreatic adenocarcinoma
• The techniques for DWI, including the choice of b-values, vary considerably
• DWI often fails to delineate pancreatic adenocarcinomas because of hyperintense pancreas
• DWI with a higher b-value can improve the tumour delineation
• The lowest image quality was obtained on DWI with b-value = 2000 s/mm 2