Dedicated imaging of the orbits can provide a wealth of information on a wide variety of lesions seen in the eye and adjacent structures. CT, with or without intravenous contrast, can be used to image bone and soft tissues and is especially useful in the setting of trauma. Axial images are obtained with a slice thickness of 2 mm with coronal and sagittal reformats.

MRI is especially useful in cases of orbital mass lesions. It is routinely performed using a head coil with images acquired in the axial, sagittal and coronal planes, with T1, T2 and post-gadolinium fat saturated sequences. A study is currently underway at the MGH comparing the conventional head coil to the more sensitive surface coil, which increases spatial resolution.

Surface coil images of the orbit.
Note the increased SNR and spatial resolution.

The most common primary ocular malignancy in adults is melanoma, arising from the pigmented choroidal layer of the eye. Exophytic mass lesion, hyperintense on T1, hypointense on T2, enhances with gadolinium.