[Establishment of an MRI-based reference intervals for exophthalmometric values in adults and evaluation of consistency between MRI and Hertel method in measuring exophthalmometric values in patients with thyroid eye disease].

<b>Objective:</b> To establish reference intervals for exophthalmometric values in adults based on MRI method, and to analyze the consistency between exophthalmometric values obtained via MRI and Hertel method in patients with thyroid eye disease (TED). <b>Method:</b> A total of 769 patients who underwent head MRI examination at the First Medical Center of the Chinese PLA General Hospital from April to September 2024 were prospectively included as a reference population, with an age [<i>M</i> (<i>Q</i>₁, <i>Q</i>₃)] of 54.0 (39.0, 64.0) years, including 369 males and 400 females. The orbital MRI axial T₂-weighted image sequence was used to measure the exophthalmometric values and to establish the reference intervals. A total of 152 TED patients aged (44.6±11.2) years old, 75 males and 77 females, from January 2013 to August 2024 in the First Medical Center of the Chinese PLA General Hospital were retrospectively included. The patients were used to evaluate the consistency of MRI and Hertel methods in measuring exophthalmometric values. Bland-Altman diagram was used to analyze the consistency of the two measurement methods, and the 95% limits of agreement(<i>LoA</i>) was calculated. The number of points exceeding the limit was <5%, which was considered to have a good consistency. <b>Results:</b> In the reference population, the exophthalmometric values for the left and right eyes were (15.8±2.1) and (15.8±2.1) mm respeclively, with reference intervals of 11.9-20.1 and 12.0-20.1 mm, respectively. Bland-Altman analysis showed that the difference in exophthalmometric values measured by the MRI and Hertel methods for the left eye was 0.66 (95%<i>LoA</i>:-4.67-5.99)mm, with 95.4% (145/152) of the measurements within this range. For the right eye, the difference was 0.28 (95%<i>LoA</i>:-4.79-5.34) mm, with 94.7% (144/152) of the measurements within this range. <b>Conclusions:</b> In this study, the reference intervals for exophthalmometric values established based on MRI for the left and right eyes of adults were 11.9-20.1 and 12.0-20.1 mm. In TED patients, the exophthalmometric values obtained by MRI and Hertel methods may not be consistent.