MRI of Pediatric Orbital Masses: Role of Quantitative Diffusion-weighted Imaging in Differentiating Benign from Malignant Lesions

Purpose: To systematically evaluate the utility of different magnetic resonance imaging (MRI) features, including quantitative diffusion-weighted imaging, in differentiating benign from malignant pediatric orbital masses. Methods: The use of MRI in 40 pediatric patients with orbital masses was retrospectively reviewed. Multiple subjective and objective MRI parameters, including lesion mean apparent diffusion coefficient (ADC) values and lesion-to-thalamus ADC ratio were recorded. Bivariate analysis was done to identify parameters that were significantly different between benign and malignant subgroups. Receiver operating curves were used to establish optimal cut-off values for lesion mean ADC and lesion-to-thalamus ADC ratio for predicting benign versus malignant lesions. Results: Lesion mean ADC, lesion-to-thalamus ADC ratio and extent of contrast enhancement showed statistically significant differences between the two subgroups. For distinguishing benign from malignant lesions, a lesion mean ADC cut-off value of 1.14 × 10⁻³ mm²/s provided a sensitivity of 84% and specificity of 100%, while an ADC ratio of 1.4 provided a sensitivity of 81% and specificity of 89%. Conclusion: Quantitative diffusion-weighted imaging can be a useful adjunct in characterizing pediatric orbital masses by MRI, and thus help in clinical decision making.