A novel method for quantitative measurement of orbital fat volume based on magnetic resonance images

OBJECTIVE: To establish a new method for rapid and quantitative measurement of orbital fat volume based on magnetic resonance imaging (MRI) data. METHODS: We collected MRI data from normalized mold and patients with the diagnosis of thyroid-associated ophthalmopathy (TAO). The cross-sectional areas of the orbital fat on each MR image slice were measured to calculate the fat volume on each slice and then the total orbital fat volume. We recorded the time for completing the measurement and assessed the precision, reliability, repeatability and interoperator variations of the results. RESULTS: This MRI data-based method allowed precise measurement of the orbital fat volumes with an absolute value of the mean percentage difference <1%. This method was fast and the results showed a good repeatability (with CVs <1%), a high reliability (ICC=0.996, 95%CI: 0.985-0.999) and a high interoperator concordance (95%CI of the Bland-Altman: -0.54-0.90). CONCLUSION: The novel method we established for orbital fat volume measurement is rapid, accurate, reliable and reproducible with a low learning cost for clinical use.