Role of diffusion-weighted MR imaging in assessing malignant versus benign skull-base lesions

This study was done to assess the role of diffusion-weighted magnetic resonance (MR) imaging in assessing malignant versus benign skull lesions.

A retrospective analysis was undertaken of 45 patients (26 male, 19 female; age range 14-68 years, mean age 39 years) with skull-base lesions. Diffusion-weighted MR images were acquired with a b-factor of 500 and 1,000 s/mm(2) using single-shot echoplanar imaging. Apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC value of the lesion was calculated.

The mean ADC value of malignant tumours was (1.002 ± 0.21) × 10(-3) mm(2)/s and that of benign tumours was (1.63 ± 0.29) × 10(-3) mm(2)/s. There was a statistically significant difference (p=0.001) in the ADC value of malignant skull-base tumours versus benign lesions. Selection of (1.3) × 10(-3)mm(2)/s as a threshold value of ADC for differentiating benign from malignant tumours yielded the best result, with an accuracy of 94%, sensitivity of 94%, specificity of 93%, positive predictive value of 93%, negative predictive value of 94% and area under the curve of 0.932.

We conclude that diffusion-weighted MR imaging is a promising, noninvasive approach that can be used to characterise skull-base lesions in that it can help differentiate malignant tumours from benign lesions and evaluate the pathological grading of malignant tumours.