Magnetic resonance imaging of uveal melanomas
R. B. Chambers, F. H. Davidorf, J. F. McAdoo and D. W. Chakeres
A series of 31 patients who presented with uveal mass lesions was studied
with magnetic resonance imaging (MRI). Uveal melanoma was the presumed
clinical diagnosis in 23 of the cases. Ten (43%) of these suspected
melanomas provided useful images on both spin-lattice (T1)- and spin-spin
(T2)-weighted studies and these had characteristic features. The features
include a high-intensity image on T1-weighted studies with progressively
decreasing relative intensity on T2-weighted images. These findings are
consistent with short T1 and T2 relaxation times. In contrast, three cases
of carcinoma metastatic to the choroid demonstrated a relatively high
signal intensity on both T1- and T2-weighted images. The short relaxation
times exhibited by uveal melanomas are in contrast with the relatively long
T1 and T2 times found in other malignant neoplasms. These characteristics
may provide a noninvasive method for differentiation of malignant melanoma
from other mass lesions within the uveal tract.
