Ocular Ultrasonography and Magnetic Resonance Imaging of Orbit in the diagnosis of Uveal Melanoma

Abstract

Uveal melanoma is a primary intraocular malignancy affecting adults. It originates from the pigmented melanocytes of the uvea present in the choroid, ciliary body and iris. The diagnosis of this tumour was conventionally based on Fundoscopy and B scan Ultrasonography. However, Magnetic Resonance Imaging (MRI) of orbit has become an important radiological imaging modality in recent times. With the advent of newer conservative eye and vision saving surgeries, MRI has assumed a central role in diagnosis as it provides useful information about the local extent of disease which has implications in planning of treatment modality. It also aids in assessment of tumour response to radiotherapy as well as follow up imaging. MRI plays a pivotal role in differentiating uveal melanoma from other benign ocular conditions and intraocular metastasis from other malignancies. Functional MRI sequences like Diffusion weighted imaging and Perfusion weighted imaging are being explored as alternatives to conventional histopathology in patients undergoing conservative therapies. Metastasis occurs in almost 50% cases of uveal melanoma and is associated with poor outcomes. Hence, prompt diagnosis and treatment of disease in early stage is essential to improve prognosis. Thus, a combination of ocular ultrasonography and Magnetic resonance imaging of the orbit has high sensitivity for the diagnosis of uveal melanoma.