Department of Chemistry IFM, Center for Molecular Imaging, University of Torino, Torino, Italy.
Contrast Media Mol Imaging. 2011 Nov-Dec;6(6):421-5. doi: 10.1002/cmmi.436.
Tumor cells were targeted with Gd-loaded/LDL (low density lipoproteins) adducts consisting of ca 300 Gd(III) amphiphilic complexes incorporated in the lipophilic LDL particles. The long reorientational time of the Gd(III) complex in the supramolecular adduct yielded a relaxivity peak at ca 1 T, whereas its relaxivity at 7 T was 5 times less. The field-dependent relaxivity markedly affected the signal enhancement attainable at the two magnetic fields. As tumor cells showed up-regulation of LDL transporters, B16 melanoma cells were labeled with the Gd-loaded/LDL adduct. Each cell contained ca 2 × 10(9) Gd atoms. Upon dispersion of 5000 labeled cells in 1 μl of agar, signal intensity (SI) enhancements of about 30 and 7% were observed at 1 and 7 T, respectively. The results obtained on cellular systems were confirmed in vivo upon the administration of Gd-loaded/LDL particles to C57 mice bearing a transplanted melanoma (B16) tumor. From the herein reported results, one may conclude that, for slowly moving Gd complexes, it is possible to obtain in vivo sensitivity enhancements at 1 T several times higher than that attained at high fields.
肿瘤细胞被靶向的 Gd 负载/LDL（低密度脂蛋白）加合物，由约 300 个 Gd(III)两亲配合物掺入亲脂性 LDL 颗粒中组成。超分子加合物中 Gd(III)配合物的长重定向时间在约 1 T 处产生弛豫率峰值，而其在 7 T 处的弛豫率则降低了 5 倍。场依赖性弛豫率显著影响了在两种磁场下可获得的信号增强。由于肿瘤细胞显示 LDL 转运蛋白的上调，B16 黑色素瘤细胞用 Gd 负载/LDL 加合物进行标记。每个细胞含有约 2×10(9)个 Gd 原子。当将 5000 个标记细胞分散在 1 μl 琼脂中时，在 1 和 7 T 下，信号强度（SI）分别增强了约 30%和 7%。在携带移植黑色素瘤（B16）肿瘤的 C57 小鼠中给予 Gd 负载/LDL 颗粒后，在体内证实了在细胞系统上获得的结果。根据本文报道的结果，可以得出结论，对于缓慢移动的 Gd 配合物，在 1 T 下获得比在高场下更高的体内灵敏度增强是有可能的。
