Clinical evaluation of ultra high field MRI for three-dimensional visualization of tumour size in uveal melanoma patients, with direct relevance to treatment planning

Abstract

Purpose : Uveal melanoma (UM) is the most common primary intraocular malignant tumour. The optimal treatment is mainly determined by the location and size of the tumour, which is presently measured with 2D ultrasound. Recent advances in ocular MRI make it possible to image the complete tumour in 3D. In this work we assess the tumour dimensions in UM patients using high-resolution ocular MRI, and we compare these values with ultrasound in order to provide improved information for treatment options.

Methods : 10 UM patients were examined on a 7Tesla MRI using a custom-built eye-coil and dedicated 3D scan sequences to minimize eye-motion-induced image artifacts. A 3D assessment of the tumour was performed to determine the maximum tumour prominence and compared with the standard clinical evaluation from 2D ultrasound images.

Results : The MRI resulted in motion-free images of the eye in which the tumour and surrounding tissues could clearly be discriminated. For 8 of 10 patients the MRI showed a slightly different value of tumour prominence (average 1.0 mm difference) than the ultrasound. For large, complexely shaped, tumours (>10mm) the MRI showed a larger maximal tumour prominence, whereas for the medium sized tumours the MRI resulted in smaller values than the ultrasound. This can be attributed to the oblique cuts made by the ultrasound which overestimate the tumour size. For two of these patients the more accurate results from the MR-images changed the treatment plan, with the smaller tumour dimensions making them eligible for eye-preserving therapy.

Conclusions : High-resolution ocular MRI can yield a more accurate measurement of the tumour dimensions than conventional ultrasound, which can result in significant changes in the prescribed treatment.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Representative images from 3 patients. (A,D,G) clinical ultrasound measurements showing the tumour prominence. (B,E,H) High-resolution 3D MR-images (using a 3D MPRAGE sequence) in which the tumour prominence is measured. (C,F,I) Additional 2D TSE-images acquired perpendicular to the tumour.

 

Comparison between ultrasound and MRI measurements of the tumour prominence of 10 UM patients. In 5 of these patients the 3D MRI evaluation revealed a smaller tumour compared to the 2D ultrasound images. In the 3 patients with a large and complexly shaped tumour, the MRI showed a larger tumour prominence.