Role of diffusion-weighted MRI in differentiation of masticator space malignancy from infection

OBJECTIVE: The aim of this study was to assess the role of the apparent diffusion coefficient (ADC) value in differentiation of masticator space malignancy from infection. METHODS: A retrospective study of 49 patients (31 male and 18 female; age range 5-66 years) with masticator space lesion was conducted. They underwent spin-echo-type echo planar diffusion-weighted MRI of the head and neck with b-values of 0 mm(2) s(-1), 500 mm(2) s(-1) and 1000 mm(2) s(-1). The ADC maps were reconstructed and the ADC value of the masticator space lesion was calculated. RESULTS: The mean (± standard deviation) ADC value of masticator space malignancy (0.91 ± 0.21 × 10(-3) mm(2) s(-1)) was significantly lower (p = 0.001) than that of masticator space infection (1.59 ± 0.32 × 10(-3) mm(2) s(-1)). When an ADC value of 1.20 × 10(-3) mm(2) s(-1) was used as a threshold value for differentiating masticator space malignancy from infection, the best result was obtained with an accuracy of 88%, sensitivity of 88%, specificity of 87%, negative predictive value of 94%, positive predictive value of 86% and area under the curve of 0.92. There was a significant difference in the ADC value between squamous cell carcinoma and soft tissue sarcoma (p = 0.001), as well as between bacterial and fungal infection of the masticator space (p = 0.001). CONCLUSION: We concluded that ADC value is a non-invasive promising imaging parameter that can be used for differentiation of masticator space malignancy from infection.