[Appearance of choroidal melanoma on high resolution MRI using 1.5T with a dedicated surface coil in 200 consecutive patients].

PURPOSE

Choroidal melanomas usually present a characteristic appearance in MRI. Differing characteristics can cause problems in differential diagnosis between melanomas and other masses in the globe. The purpose of this study was to evaluate the appearance of choroidal melanomas with MRI in a large consecutive patient group.

METHODS

In a prospective study, 200 patients with choroidal melanomas were investigated with MRI using a 1.5 T scanner and a 5 cm surface coil. Both quantitative and qualitative evaluation of the resulting images was performed.

RESULTS

78.5% of the melanomas presented with homogeneous signal intensities within the tumor due to a homogeneous pigmentation whereas 21.5% of the melanomas demonstrated a mixed pigmentation. Signal intensities of the homogeneous melanomas in the plain T1-WI were moderately or markedly hyperintense compared to the vitreous in 29.3% and moderately or markedly hypointense in the T2-WI in 37.1%. An accompanying retinal detachment was found in 65.5% and an extraocular growth in 7.0%.

CONCLUSIONS

In 10% to 37% we observed the typical well known MR appearance, including homogeneous high signal in the T1-WI and low signals in the T2-WI. For further differentiation, morphological criteria (e.g. shape, size, and position) were used, which are also discussed.