Orbital pseudo tumor (MR).

This image is T1 with fat supression  of the orbit; the right orbit is completely supressed from the fat while the left one shows evidence of diffuse increased intensity.

After giving contrast injection; this image shows diffuse increased enhancement of the retro orbital fat of the left side while the right one shows no enhancement.

Discussion:

• The first image shows left orbital diffuse hyper intensity after fat supression due to presence of inflammatory fluid which was masked before by the fat.
• After giving contrast; the lesion shows abnormal enhancement which include also the visualized orbital muscles and the left lacrimal gland.
• This an example of a case of orbital pseudo tumor.
• To differentiate between orbital pseudo tumor and Grave's disease causing orbital muscle enlargement; look to the tendon of the muscles; if they involved by thickening and enhancement; consider the case as orbital pseudo tumor; and if not; consider it Grave's disease.