Application of diffusion-weighted MR imaging with ADC measurement for distinguishing between the histopathological types of sinonasal neoplasms

PURPOSE: To evaluate the potential contribution of quantitative DWI parameters including ADC mean and ADC ratio values to help in distinguishing the histopathological types of sinonasal neoplasms.

METHODS: This retrospective study included 83 patients (50 males, 33 females; mean age 61 years) with pathologically proven untreated sinonasal neoplasms who have undergone diffusion-weighted MRI imaging from February 2010 to August 2017. Diffusion-weighted MRI was performed on a 3 T unit with b factors of 0 and 1000 s/mm 2, and ADC maps were generated. Mean ADC values of sinonasal tumors and ADC ratios (ADC mean of the tumor to ADC mean of pterygoid muscles) were compared with the histopathological diagnosis by utilizing the Kruskal-Wallis non-parametric test.

RESULTS: Mean ADC mean and ADC ratio were 0.8 (SD, ±0.4) × (10 -3 mm 2/s) and 1.2 (SD, ±0.5), respectively, and each parameter was significantly different between histopathological types (p < 0.05). Mean ADC mean and ADC ratio were higher in adenoid cystic carcinoma (ACC) than in SCC, lymphoma, neuroendocrine carcinoma and sinonasal undifferentiated carcinoma (SNUC) (p < 0.05). Optimized ADC mean thresholds of 0.79, 0.81, 0.74 and 0.78 (10 -3 mm 2/s) achieved maximal discriminatory accuracies of 100%, 79%, 100% and 89% for ACC/SNUC, ACC/SCC, ACC/neuroendocrine carcinoma, and ACC/lymphoma, respectively.

CONCLUSIONS: The optimized ADC mean threshold of 0.80 (10 -3 mm 2/s) could be used to differentiate ACC from non-ACC sinonasal neoplasms with maximal discriminatory accuracy (82%) and sensitivity of 100%. However, there is considerable overlapping of the ADC mean and ADC ratio values among non-ACC sinonasal neoplasms hence surgical biopsy is still needed.