MR‐imaging biomarkers for eye tumors

In the clinical care for eye tumor patients, more and more applications of magnetic resonance imaging (MRI) have emerged in the last years. In retinoblastoma, for example, it is routinely used to screen for tumor invasion in the optic nerve. In uveal melanoma, the most frequently occurring primary intraocular malignancy in adults, MRI's three‐dimensional visualization of the tumor and surrounding structures give it an increasingly prominent place in radiotherapy planning. As a result of these clinical applications, functional MRI‐parameters, which are often obtained in the same scan session, gain in relevance. These functional sequences non‐invasively obtain tumor biomarkers that can be used for differential diagnosis, prognosis and response assessment. In this lecture we will cover the most important MR‐biomarkers, explain the underlying biology they probe, and highlight their clinical and scientific applications.

We will start with perfusion‐weighted MRI (PWI), a technique that obtains information on the tumor perfusion by administering an intravenous contrast agent while continuously imaging the eye. In addition to explaining the various pharmacokinetic models to quantitatively assess these data, we will show how, the clinically more feasible, semi‐quantitative assessment can already be used for differential diagnosis and early assessment of treatment response. Subsequently, we will discuss diffusion weighted imaging (DWI), a biomarker of the lesion's cellularity. Although it is a powerful biomarker to discriminate between benign and malignant lesions, its clinical value for prognosis and treatment response are still debated. We will end with a few clinical cases that demonstrate how these and other MR‐biomarkers complement the conventional ophthalmic imaging.