Assessment of Masses of the External Ear With Diffusion-Weighted MR Imaging

Abstract

Purpose: To assess masses of the external ear with diffusion-weighted MR imaging.

Material and methods: Retrospective analysis of 43 consecutive patients with soft tissue mass of the external ear. They underwent single shot diffusion-weighted MR imaging of the ear. The apparent diffusion coefficient (ADC) value of the mass of the external ear was calculated. The final diagnosis was performed by biopsy. The ADC value correlated with the biopsy results.

Results: The mean ADC value of malignancy (=27) of external ear (0.95 ± 0.19 × 10 mm/s) was significantly lower (p = 0.001) than that of benign (n = 16) lesions (1.49 ± 0.08 × 10 mm/s). The cutoff ADC used for differentiation of malignancy from benign lesions was 1.18 × 10 mm/s with an area under the curve of 0.959, an accuracy of 93%, a sensitivity of 92%, and specificity of 93%. There was a significant difference in the ADC of well and moderately differentiated malignancy versus poorly and undifferentiated squamous cell carcinoma (p = 0.001), and stages I and II versus stages III and IV (p = 0.04) of squamous cell carcinoma.

Conclusion: ADC value is a non-invasive promising imaging parameter that can be used for differentiation of malignancy of the external ear from benign lesions, and grading and staging of squamous cell carcinoma of the external ear.