Synopsis

Overall intraobserver agreement for ADC- and IVIM-derived parameters was excellent.

Perfusion-related IVIM-derived parameters are the most reliable for differentiation between pancreatic ductal adenocarcinoma and neuroendocrine neoplasms. No significant differences were found between ADC- and IVIM-derived parameters of mass-forming pancreatitis and carcinoma.

Purpose

To evaluate measurement reliability and the diagnostic potential of apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM)–derived parameters of solid pancreatic masses including ductal adenocarcinoma (PDAC), neuroendocrine neoplasm (panNEN), mass forming pancreatitis (MFP), and normal pancreas.

Material and methods

48 consecutive patients with pathologically confirmed pancreatic tumors (31 PDACs and 17 panNENs), 4 patients with mass-forming pancreatitis (MFP), and 30 patients with a normal pancreas were included in this study. All patients underwent 1.5-T MR imaging, including IVIM diffusion-weighted imaging with 11 b values (from 0 to 800 sec/mm2). ADC, true diffusion (D), pseudo diffusion (D*), and perfusion fraction (f) were calculated by placing regions of interest (ROIs) within each lesion and within normal pancreas. Intraobserver reliability of the measurements was assessed by using the intraclass correlation coefficient (ICC). A Kruskal-Wallis H test with pairwise comparisons using Dunn’s procedure with a Bonferroni adjustment was used for comparison. The diagnostic performance of the parameters was evaluated by using receiver operating characteristic (ROC) analysis.

Results

Overall intraobserver agreement was excellent (ICC= .996, .991, .995, .993, and .981 for ROI size, ADC, f, D and D*, respectively). D* and f values of PADCs were significantly lower than those of normal pancreas and panNENs (P< .05). For differentiation of PDACs from panNENs, perfusion-related parameters (f and D*) showed a significant difference (P<.001 for both) and had the highest AUC (.981 and .829) in ROC analysis. No significant differences were found between ADC- and IVIM-derived parameters of MFP and PDACs.

Conclusion

The measurement of ADC- and IVIM-related parameters has excellent reproducibility. Perfusion-related parameters could be helpful in distinguishing PDACs from panNENs.

Acknowledgements

No acknowledgement found.

References

No reference found.