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Evaluation of a technique for estimation of extraocular muscle volume using 2D MRI

Lookup NU author(s): Dr Michael FirbankORCiD


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Measurements of extraocular muscle volume may be useful as an outcome indicator in the assessment of treatment options in thyroid-associated ophthalmopathy. In this study, a technique for estimating extraocular muscle volume from two-dimensional T-1 weighted MR images acquired in the coronal plane is described. For each image slice, the cross-sectional area of individual extraocular muscles was estimated using a combination of semi-automated outlining based on a local thresholding technique and manual outlining where thresholding was not possible. The technique was assessed using three sets of images: a computer-generated virtual image set with "extraocular muscles" of known volumes; a set of images from 19 biochemically and clinically euthyroid patients; and images from 7 patients with thyroid-associated ophthalmopathy. From the computer-generated images, the accuracy was determined as 7.6%. Intraobserver agreement was investigated using repeated MRI scans on a single subject and repeat outlining of muscles on five sets of images from different subjects. The mean difference between repeat measurements was 2% (SD 5.9%). We conclude that two-dimensional MR images can be used to determine changes in muscle volume of greater than 12% during treatment of thyroid-associated ophthalmopathy.

Publication metadata

Author(s): Firbank MJ, Coulthard A

Publication type: Article

Publication status: Published

Journal: British Journal of Radiology

Year: 2000

Volume: 73

Issue: 876

Pages: 1282-1289

ISSN (print): 0007-1285

ISSN (electronic): 1748-880X

Publisher: The British Institute of Radiology