Two diffusion weighted imaging modes for differential diagnosis of pancreatic neuroendocrine tumor and solid-pseudopapillary tumor

Objective：To investigate the differential value of two diffusion weighted imaging using respiratory-gating and breath-hold methods for differential diagnosis of pancreatic neuroendocrine tumor (PNET) and solid-pseudopapillary tumor (SPT). Methods：Fifteen cases of SPT and 17 cases of PNET were enrolled in this study, and all were proven by histopathology. A 3.0T magnetic resonance scanner was used. On the basis of spin echo-echo planar imaging sequence, a diffusion gradient with a b value of 600 s/mm2 was applied in three axes. Diffusion weighted imaging methods included respiratory gating and breath-holding. A gradient pulse with an angle of 180° and 220 ms inversion recovery time was conducted before turning to diffusion gradient pulse for the respiratory-gated signal acquisitions. Pancreatic artifacts and ADC value of the lesions were compared between the two methods, and the differential diagnosis value of the two methods for SPT and PNET were evaluated. Results：Pancreatic artifacts were less observed using the respiratory-gating mode compared with the breath-holding mode, with a statistical difference (P=0.000). For the breath-holding mode, the ADC value of PNET was higher than that of SPT, but no statistical difference was observed. For respiratory-gating mode, the ADC value of PNET was statistically higher than that of SPT (P=0.000). Conclusions：Diffusion weighted imaging with the respiratory-gating mode is superior to the breath-holding mode for the differential diagnosis of SPT and PNET.