Biomedical Magnetic Resonance Research Group, Louvain Drug Research Institute, Université Catholique de Louvain, Avenue Mounier 73.40, 1200, Brussels, Belgium.
Contrast Media Mol Imaging. 2014 Mar-Apr;9(2):154-60. doi: 10.1002/cmmi.1554.
Melanoma is the most dangerous form of skin cancer and its incidence is rising each year. Because the current methods of diagnosis based on the visual aspect of the tumor show limitations, several new techniques are emerging to help in this diagnosis, amongst which are magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR). The origin of the typical contrast pattern observable in melanoma in T1 - and T2 -weighted images remains to be elucidated and is a source of controversy. In addition, melanin could create sufficient magnetic inhomogeneities to allow its visualization on T2 *-weighted images using high-field MRI. In order to elucidate the possible role of melanin in the MRI contrast of melanoma, the present study was designed to correlate the paramagnetic content in melanin pigment to the contrast on T1 -, T2 - and T2 *-weighted images. MR images were obtained in vivo at 11.7 T using four types of experimental tumors with different pigmentations (B16, HBL, LND1 melanomas and KHT sarcomas). The paramagnetic content in melanin pigment was measured by EPR. No significant correlation was observed between the content in melanin and the relaxation times T1 , T2 and T2 *, emphasizing that the presence of pigment alone has negligible effect on the MRI contrast.
黑色素瘤是最危险的皮肤癌形式，其发病率每年都在上升。由于目前基于肿瘤外观的诊断方法存在局限性，因此出现了几种新的技术来帮助进行这种诊断，其中包括磁共振成像（MRI）和电子顺磁共振（EPR）。在 T1 - 和 T2 -加权图像中观察到的黑色素瘤典型对比模式的起源仍有待阐明，这也是争议的来源。此外，黑色素可能会产生足够的磁各向异性，从而允许在使用高磁场 MRI 的 T2 *-加权图像上对其进行可视化。为了阐明黑色素在黑色素瘤 MRI 对比中的可能作用，本研究旨在将黑色素中的顺磁含量与 T1 - 、 T2 - 和 T2 *-加权图像上的对比度相关联。在 11.7 T 下使用具有不同色素沉着的四种类型的实验肿瘤（B16、HBL、LND1 黑色素瘤和 KHT 肉瘤）在体内获得 MR 图像。通过 EPR 测量黑色素中的顺磁含量。未观察到黑色素含量与弛豫时间 T1 、 T2 和 T2 *之间存在显著相关性，这强调了仅存在色素对 MRI 对比的影响可以忽略不计。
