Abstract
PurposeTo evaluate the magnetic resonance imaging (MRI) characteristics of uveal melanoma (UM), to compare them with fundoscopy and ultrasound (US), and to validate them with histopathology.MethodsMR images from 42 UM were compared with US and fundoscopy, and on 14 enucleated cases with histopathology.ResultsA significant relationship between the signal intensity on T1 and pigmentation on histopathology was found (p=0.024). T1 hyperintense UM were always moderately or strongly pigmented on histopathology, while T1-hypointense UM were either pigmented or non-pigmented. Mean apparent diffusion coefficient (ADC) of the UM was 1.16 ± 0.26 × 10−3 mm2/s. Two-thirds of the UM had a wash-out and the remaining a plateau perfusion time-intensity curve (TIC). MRI was limited in evaluating the basal diameter of flat tumors. US tends to show larger tumor prominence (0.5mm larger, p=0.008) and largest basal diameter (1.4mm larger, p<0.001). MRI was good in diagnosing ciliary body involvement, extrascleral extension, and optic nerve invasion, but limited on identifying scleral invasion. An increase of tumor prominence was associated with lower ADC values (p=0.030) and favored a wash-out TIC (p=0.028). An increase of tumor ADC correlated with a plateau TIC (p=0.011).ConclusionsThe anatomical and functional MRI characteristics of UM were comprehensively assessed. Knowing the MRI characteristics of UM is important in order to confirm the diagnosis and to differentiate UM from other intra-ocular lesions and because it has implications for treatment planning. MRI is a good technique to evaluate UM, being only limited in case of flat tumors or on identifying scleral invasion.
Highlights
Uveal melanoma (UM) is the most common primary intraocular malignancy in adults [1,2,3,4]
Retrospectively and mainly with the help of multiplanar reconstructions, a mushroom configuration was found on magnetic resonance imaging (MRI) as well
Imaging UM with MR requires a dedicated eye protocol consisting of 2D MS TSE sequences, which are indispensable for delineating tumor boundaries; 3D TSE sequences, which allow retrospective reformatting in all directions and 3D reconstructions, and are essential to assess tumor geometry and accurate measurements; and diffusion weighted imaging (DWI) and Perfusion weighted imaging (PWI) sequences, which aid in the differential diagnosis, and potentially, provide prognostic information, predict treatment response, and permit earlier assessment of tumor response to radiotherapy than US [3, 8, 11, 14,15,16,17,18]
Summary
Uveal melanoma (UM) is the most common primary intraocular malignancy in adults [1,2,3,4]. The diagnosis with these conventional ophthalmic imaging modalities is difficult in smaller uveal melanomas/melanocytic lesions, in atypical tumors, in lesions behind the iris, and in case of opacification of the ocular media. US has limitations in pre-treatment planning of UM and during followup, being only able to evaluate dimensional changes of the lesion. Another option for imaging the globe is magnetic. With a high soft tissue contrast and spatial resolution, the possibility of generating 3D volumetric and functional images, and the possibility of evaluating UM in eyes of vitrectomized patients with a SiOil tamponade, MRI seems to be of added value in comparison with US [8, 11,12,13]
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