Apparent diffusion coefficients of benign and malignant salivary gland tumors. Comparison to histopathological findings

Abstract

Objective To evaluate the apparent diffusion coefficient (ADC) of benign and malignant salivary gland tumors in comparison to histopathological findings. Materials and methods This study included 32 patients with a wide spectrum of major salivary gland tumors (17 benign, 15 malignant). Diffusion-weighted imaging (DWI) and ADC measurements were performed in all patients. The degrees of extracellular components (myxoid and chondroid matrices, microcysts and hyalinization), were histopathologically classified as mild, moderate and conspicuous. Comparisons were made of mean ADC values between benign and malignant tumors, and among tumors showing different degrees of extracellular components. Results Mean ADC values were 1.09 ± 0.34 × 10 −3 mm 2/s in malignant salivary gland tumors and 1.40 ± 0.43 × 10 −3 mm 2/s in benign salivary gland tumors. No significant difference in mean ADC values was found between benign and malignant tumors ( P > 0.05). However, mean ADC values increased with the degree of extracellular components. Mean ADC values were significantly different between mild and moderate degrees ( P < 0.05) of extracellular components, and between mild and conspicuous degrees ( P < 0.05), in both benign and malignant tumor groups. Conclusion In this study, ADC values alone did not allow differentiation between benign and malignant salivary gland tumors. Comparison with histopathological findings suggests a correlation between the amount of extracellular components and mean ADC values in salivary gland tumors.