Role of magnetic resonance imaging (MRI) including diffusion weighted images (DWIs) in assessment of parotid gland masses with histopathological correlation

Abstract

Aim: Detect the most reliable MR signs differentiating between benign and malignant parotid masses & assess the role of ADC value calculation in the determination of the parotid lesions nature. Patient and method: Prospective study carried on 48 patients (21 male and 27 female) presented with parotid masses. They underwent MRI, diffusion weighted images (DWIs) with apparent diffusion coefficient (ADC) value calculation. Results were correlated with histopathological data. Results: Significant statistical difference between malignant and benign lesions was found in the site within the gland (p value 0.002), border definition (p value < 0.001), diffuse pattern of growth (p value < 0.001), low T2WIs signal (p value 0.032), infiltration of surrounding structures (p value < 0.001) and degree of contrast enhancement (p value 0.002). Receiver operating characteristics (ROC) curve analysis of ADC value revealed cut off value of 0.874 × 10−3 mm2/sec at maximum sensitivity and specificity of 62.5% and 75% respectively. Conclusion: Illdefined border, diffuse growth pattern and infiltration of surrounding structures are specific MR signs of parotid mass malignancy. Involvement of both parotid lobes, low T2WIs signal and high degree of contrast enhancement are suggestive signs of malignancy. ADC value had appreciable add value in parotid mass evaluation.