The value of the apparent diffusion coefficient calculated from diffusion-weighted magnetic resonance imaging scans in the differentiation of maxillary sinus inflammatory diseases

Objectives. This study examined the value of the apparent diffusion coefficient (ADC) calculated by using diffusion-weighted imaging (DWI) in the differentiation of inflammatory lesions of the maxillary sinus. Study Design. Sixty-five maxillary sinus magnetic resonance imaging (MRI) scans with findings suggestive of inflammatory lesions were qualitatively categorized into 4 distinct groups by using T2-weighted images: group 1: presence of mucosal thickening; group 2: presence of sinonasal polyps or mucous retention cysts; group 3: presence of fluid identified by air-fluid levels with a homogeneous signal intensity; and group 4: presence of fluid identified by air-fluid levels with a heterogeneous signal intensity. The ADC of each imaging finding was measured by using a 5-mm area of interest. Statistical differences between the groups were determined by using nonparametric tests with a 5% significance level. Results. Statistically significant differences were observed between group 1 and the other groups. Mucosal thickening was associated with lower ADC values compared with the other inflammatory lesions. Conclusions. The ADC can be useful in differentiating mucosal thickening from other inflammatory alterations in the maxillary sinuses. Mucosal thickening had more restricted water diffusion compared with the other inflammatory lesions.