Preliminary study of positron emission tomography in the detection and management of orbital malignancy

To determine the clinical efficacy of positron emission tomography (PET) in the treatment of patients with orbital malignancy.

Prospective, consecutive case series to assess the ability of PET to (1) identify lesions previously demonstrated on CT or MRI; (2) characterize the metabolic activity of these lesions; and (3) determine the presence of metabolically active metastases elsewhere in the body.

Eighteen patients with suspected orbital malignancies, ages 32 to 78 years, underwent PET in addition to CT and/or MRI. Sixteen of 18 also underwent orbital biopsy. Histopathologic diagnosis included lymphoma (55%), carcinoma (22%), melanoma (11%), sarcoma (5.5%), and lymphoid hyperplasia (5.5%). All orbital lesions were seen on conventional imaging. Overall, 61% of orbital lesions were demonstrated on PET, including 55% of tumors that were lymphoproliferative and 100% (n = 5) of other malignancies. PET was useful in ruling out tumor recurrence after exenteration in 2 patients.

In this small clinical series, PET proved effective in demonstrating nonlymphoproliferative orbital malignancy. This series is too small to study any correlation between histopathologic aggressiveness and PET findings in orbital lymphoma.