Mandeville J B, Moore J, Chesler D A, Garrido L, Weissleder R, Weisskoff R M
MGH-NMR Center, Charlestown, MA 02129, USA.
Magn Reson Med. 1997 Jun;37(6):885-90. doi: 10.1002/mrm.1910370613.
In vivo effective relaxation rates in normal rat liver were evaluated for four dextran coated iron oxide agents: monocrystalline iron oxide nanocolloid (MION) with a mean particle diameter of 3.9 nm, a polycrystalline agent (PION) with a larger mean diameter of 12 nm, and these two agents labeled with the asialofetuin (ASF) protein for high hepatocytic receptor binding affinity (MION-ASF and PION-ASF). Using echo planar imaging at 2 Tesla, dose response was measured with measured with high temporal resolution for 3 h after injection of agent, and by comparing with relaxivities in vitro and in brain, dominant in vivo contrast phenomena were elucidated. While transverse relaxivity for PION-ASF exceeded that for MION-ASF by almost a factor of 2 in solution, relaxation rates in vivo became equivalent. Liver relaxation using non-ASF agents was consistent with rapid water exchange between vascular and extravascular compartments, which dominated relaxation as a result of agent accumulation in Kupffer cells.
平均粒径为3.9 nm的单晶氧化铁纳米胶体（MION）、平均粒径较大为12 nm的多晶制剂（PION），以及这两种与去唾液酸胎球蛋白（ASF）蛋白结合以实现高肝细胞受体结合亲和力的制剂（MION-ASF和PION-ASF）。在2特斯拉下使用回波平面成像，在注射制剂后3小时内以高时间分辨率测量剂量反应，并通过与体外和脑内的弛豫率进行比较，阐明了主要的体内对比现象。虽然在溶液中PION-ASF的横向弛豫率比MION-ASF高出近2倍，但体内弛豫率变得相当。使用非ASF制剂时肝脏的弛豫与血管和血管外间隙之间的快速水交换一致，由于制剂在库普弗细胞中的积累，这种水交换主导了弛豫。
