A new MRI method for the quantitative evaluation of extraocular muscle size in thyroid ophthalmopathy

Abstract

In cross section, extraocular muscles are more or less elliptical, with short and long diameters. We studied the ratio (R) of short to long diameter and investigated its use in quantitative assessment of the extraocular muscles in patients with Graves's disease. We measured the diameters on T1-weighted axial and coronal MRI and computed R for each extraocular muscle in 80 patients without and 40 with Graves's disease. We compared the measurements and R of the right and left orbits, and of men and women. The short diameter of all extraocular muscles apart from the superior oblique showed significant differences between men and women, and that of the inferior rectus varied significantly with age. R, however, was unrelated to sex or age. All patients with Graves's disease and an increased short diameter also had an increased R, but 6% of the muscles showed an increase in R, even though their short diameter was within the normal range.

Relationship of inferior oblique overaction to muscle bulk and position

“…MRI studies on extraocular muscles also confirm the above findings. 9,[14][15][16][17][18][19][20] In the last few years, research by some authors, especially Demer, not only changed the traditional concepts of diagnosis and treatment in strabismus but also the anatomic concepts of extraocular muscles. [15][16][17][18][19] Demer proposed the concept of muscle pulley and suggested use of the term ''over elevation in adduction'' instead of ''inferior oblique overaction.''…”

Inferior oblique muscle thickness in Asians

“…The ratio of short to long axes was also calculated (Aydin et al 2003). Laterality and difference in gender were statistically analyzed using a Mann-Whitney U-test.…”

Diagnose und Differenzialdiagnose der endokrinen Orbitopathie in der MRT

“…Eine Größenmessung oder Volumetrie der Augenmuskeln ist mit der MRT möglich [1,32]. Da jedoch MRT-morphologisch keine Normalwerte etabliert sind, die Diameter und das Volumen vom Alter, dem Geschlecht, der Rasse und ethnischen Unterschieden abhängen [1], bringt eine Größenmessung oder Volumetrie im klinischen Alltag keine Zusatzinformation, sodass der visuelle Bildeindruck entscheidend ist.…”