Abstract
AbstractPurposeWe aim to evaluate 3D definitions of prominence for uveal melanoma (UM), and compare US and contrast‐enhanced T1‐weighted MRI measurements for the most appropriate definitions.Methods25 UM patients were scanned at 3 Tesla MRI with a 4.7 cm surface coil [1]. The tumour was delineated on the 3D contrast‐enhanced T1‐weighted images (voxel size 0.8 x 0.8 x 0.8 mm3). Three prominence definitions were evaluated. Promhaus: the distance to the tumour point most distal from sclera. Promsclera: similar to promhaus, but distances are measured perpendicular to the sclera. Promcentre: distance between most interior part of the tumour and sclera. The most appropriate definition was chosen and compared to the clinical ultrasound measurements. Differences >0.5 mm were considered significant.ResultsFor 13/25 patients, there was no significant difference between three definitions. For 12 patients, promsclera or promhaus yielded an oblique measurement or a measurement at the tumour edge. As these measurements are unsuitable for radiotherapy dose calculations, promcentre was selected as the most appropriate definition. For 7 patients, the difference between the US prominence and promcentre was >0.5mm (median absolute difference 0.3 mm, range 0.0–1.6 mm). In 3/7 patients, the MRI measurement was considered more accurate than the US measurement, as the tumour top was not visualized on US.ConclusionsAfter evaluation of 3D prominence definitions for MRI, the median absolute prominence difference (0.3 mm) was below the MRI voxel size and the inter‐observer variability for US measurements [2]. Largest differences were observed in patients where US tumour visualization was incomplete, in which case MRI was preferred. For prominence differences in patients with tumours adjacent to the optic nerve or with enhancing sclera, further study is needed to determine the most accurate method.Bibliography:1. Ferreira et al. Cancers (2019)2. Haritoglu et al. Br J Opth (2002)
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