This 59 year-old female patient presented with acute right hemiplegia, aphasia and confusion. She had a known cerebral melanoma metastasis in the left frontal lobe. This axial T2-weighted MR (click image for arrows) shows a large haematoma with a fluid-fluid level (green arrows). There is a smaller low signal area anteriorly (red arrows) which corresponded to the known metastasis. This smaller area enhanced after gadolinium, as did the overlying dura.
Melanoma metastases may be hyperintense on T1W images and demonstrate signal loss on T2 or T2* sequences. This is due to the presence of both melanin and blood products. Melanoma metastases are 5 times more likely to show signal loss on T2* images than lung metastases, and 4.5 times more likely to be T1 hyperintense. T1 hyperintensity correlates with melanin content better than does T2* signal loss. T2* imaging (or susceptibility-weighted imaging) may be useful in screening for melanoma metastases as lesions are more conspicuous.
Reference: Gaviani P, et al. Improved Detection of Metastatic Melanoma by T2*-Weighted Imaging. American Journal of Neuroradiology 27:605-608, March 2006Credit: Dr Laughlin Dawes