Diffusion-weighted Magnetic Resonance Imaging (DWI MRI)
provides a quantitative measure of disease activity and can be used as an adjunct to clinical assessment in Gravesí Orbitopathy (GO)
Feeney, Farzana Rahman, Ravi Lingam, Vickie Lee, Central Middlesex Hospital,
London Northwest Healthcare NHS Trust
Early diagnosis and treatment of Gravesí
orbitopathy (GO) are essential to prevent physical and psychological
burdens of advanced disease. MRI diffusion weighted imaging (DWI MRI) is an
emerging modality to assist with timely diagnosis. We
investigated the value of DWI MRI in early diagnosis and monitoring and its
relationship with the clinical activity score (CAS)
in a multidisciplinary thyroid eye clinic at Central Middlesex Hospital.
Methods: Ninety-one patients were referred to the clinic between
2011 and 2016. Forty-seven
had clinical indices of orbital involvement and underwent MRI DWI imaging. Of these, 20 patients had at least one further scan during
the course of the disease. The apparent diffusion coefficient (ADC) was
calculated for the most affected muscle on each DWI scan and correlated with
Results: Thirteen patients received intravenous
methylpredisolone, 5/20 completed orbital radiotherapy and 3/20 had an orbital decompression during monitoring. The most active muscle at presentation was the right
inferior rectus (n=7, 35%).
Mean CAS at presentation was 2.3/7,
followed by CAS 1.2, 0.8 and 0.0 at scan 2, 3 & 4
respectively. Mean ADC value fell over the disease course during treatment from
1120.5 to 766.5. A positive correlation was found between initial CAS and ADC
(r=0.45, p=0.04). All patients who did not subsequently develop significant disease had ADC values <1000 (mean 674.7) at baseline.
Conclusions: We present a positive correlation
between orbital DWI MRI and CAS in GO. DWI MRI may offer predictive benefit in
GO. High ADC values identified prior to other clinical disease parameters may
help target patients at high risk of developing severe GO. DWI may also serve
as a valuable adjunct in early diagnosis and monitoring with potential to identify
low risk groups whereby low CAS at baseline combined with DWI <1000 may
predict a relatively quiet disease course.