title: Signal intensity, clinical activity and cross-sectional areas on MRI scans in thyroid eye disease.
abstract: The signal intensity from inflamed extra-ocular muscles on short tau inversion recovery (STIR)-sequence magnetic resonance imaging (MRI) is known to correlate with clinical scores of thyroid eye disease (TED) severity. Twenty-one patients who had undergone repeated MRI scanning for TED were studied retrospectively. Signal intensity of extra-ocular muscles (from STIR-sequence MRI) and cross-sectional area (from STIR and T1 MRI) were correlated with Mourits' clinical activity score (CAS). The area of highest signal intensity within the most inflamed extra-ocular muscle, and the average cross-sectional signal intensity of the most inflamed extra-ocular muscle reliably correlated with CAS, and this was maintained as disease activity changed over time. In contrast, isolated measures of muscle cross-sectional area did not correlate with CAS. The extra-ocular muscle cross-sectional area calculated from STIR-sequence MR images was greater than that measured on T1 images. This suggests that muscle area from STIR-sequence MRI may also detect peri-muscular inflammation. We conclude that the peak signal intensity from the most inflamed extra-ocular muscle remains the most reliable correlate of clinical disease activity obtained from these images. STIR-sequence MRI scans provide a number of useful measures of disease activity in TED.
authors.affiliation: Bristol Eye Hospital, Lower Maudlin Street, Bristol BS1 2LX, UK.
authors.forename: E J
authors.initials: EJ
authors.lastname: Mayer
authors.forename: D L
authors.initials: DL
authors.lastname: Fox
authors.forename: G
authors.initials: G
authors.lastname: Herdman
authors.forename: J
authors.initials: J
authors.lastname: Hsuan
authors.forename: J
authors.initials: J
authors.lastname: Kabala
authors.forename: P
authors.initials: P
authors.lastname: Goddard
authors.forename: M J
authors.initials: MJ
authors.lastname: Potts
authors.forename: R W J
authors.initials: RW
authors.lastname: Lee
mesh_terms: D019412:Anatomy, Cross-Sectional / Q000379:methods*; D018450:Disease Progression; D005260:Female; D049970:Graves Ophthalmopathy / Q000175:diagnosis*; D006801:Humans; D007249:Inflammation / Q000175:diagnosis; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D015588:Observer Variation; D009801:Oculomotor Muscles / Q000033:anatomy & histology* / Q000473:pathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index