The added value of intravoxel incoherent motion diffusion weighted imaging parameters in differentiating high-grade pancreatic neuroendocrine neoplasms from pancreatic ductal adenocarcinoma

The aim of the present study was to investigate the potential significance of intravoxel incoherent motion (IVIM)-diffusion weighted imaging (DWI) in differentiating high-grade pancreatic neuroendocrine neoplasms (pNENs) from pancreatic ductal adenocarcinoma (PDAC). A total of 50 patients, including 37 patients with PDAC and 13 patients with high-grade pNENs, underwent pancreatic multiple b-values DWI with 15 b-values including 0, 10, 20, 40, 60, 80, 100, 150, 200, 400, 800, 1,000, 1,200, 1,500 and 2,000 sec/mm(2). Standard apparent diffusion coefficient (ADC(standard)) and IVIM parameter [slow apparent diffusion coefficient (D(slow)), fast apparent diffusion coefficient (D(fast)), fraction of fast apparent diffusion coefficient (ƒ)] values of PDAC and pNENs were compared. P<0.05 was considered to indicate a statistically significant difference. Receiver operating characteristics analysis was performed in order to evaluate the diagnostic potential of IVIM parameters for differentiating high-grade pNENs from PDAC. D(slow) of pNENs was significantly lower compared with that of PDAC (0.460 vs. 0.579×10(−3) mm(2)/sec; P=0.001). D(fast) of pNENs was significantly higher compared with that of PDAC (13.361 vs. 4.985×10(−3) mm(2)/sec; P<0.001). Area under the curve of D(slow), D(fast) and combined D(slow) and D(fast) was 0.793, 0.863 and 0.885 respectively. The specificity and sensitivity of D(slow)≤0.472×10(−3) mm(2)/sec were 97.3 and 53.9%, respectively, for differentiating high-grade pNENs from PDAC. The specificity and sensitivity of D(fast) >9.58×10(−3) mm(2)/sec were 91.9 and 69.2%, respectively, for differentiating high-grade pNENs from PDAC. When D(slow) and D(fast) were combined, the specificity and sensitivity for differentiating high-grade pNENs from PDAC were 76.9 and 100%, respectively. Taken together, these results indicated that the diffusion-associated parameter D(slow) and the perfusion-associated parameter D(fast) of IVIM-DWI may differentiate high-grade pNENs from PDAC with high diagnostic accuracy, and that IVIM-DWI may be a valuable biomarker in differentiating pancreatic neoplasms.