Beaumont Marine, Lemasson Benjamin, Farion Régine, Segebarth Christoph, Rémy Chantal, Barbier Emmanuel L
INSERM, U836, Grenoble, France.
J Cereb Blood Flow Metab. 2009 Oct;29(10):1714-26. doi: 10.1038/jcbfm.2009.86. Epub 2009 Jul 8.
This study aimed at combining an iron-based, steady-state, vessel size index magnetic resonance imaging (VSI MRI) approach, and a gadolinium (Gd)-based, dynamic contrast-enhanced MRI approach (DCE MRI) to characterize tumoral microvasculature. Rats bearing an orthotopic glioma (C6, n=14 and RG2, n=6) underwent DCE MRI and combined VSI and DCE MRI 4 h later, at 2.35 T. Gd-DOTA (200 mumol of Gd per kg) and ultrasmall superparamagnetic iron oxide (USPIO) (200 micromol of iron per kg) were used for DCE and VSI MRI, respectively. C6 and RG2 gliomas were equally permeable to Gd-DOTA but presented different blood volume fractions and VSI, in good agreement with histologic data. The presence of USPIO yielded reduced K(trans) values. The K(trans) values obtained with Gd-DOTA in the absence and in the presence of USPIO were well correlated for the C6 glioma but not for the RG2 glioma. It was also observed that, within the time frame of DCE MRI, USPIO remained intravascular in the C6 glioma whereas it extravasated in the RG2 glioma. In conclusion, VSI and DCE MRI can be combined provided that USPIO does not extravasate with the time frame of the DCE MRI experiment. The mechanisms at the origin of USPIO extravasation remain to be elucidated.
本研究旨在将基于铁的稳态血管大小指数磁共振成像（VSI MRI）方法与基于钆（Gd）的动态对比增强磁共振成像方法（DCE MRI）相结合，以表征肿瘤微血管系统。携带原位胶质瘤（C6，n = 14；RG2，n = 6）的大鼠在2.35 T磁场下先接受DCE MRI检查，4小时后再接受VSI和DCE MRI联合检查。DCE MRI和VSI MRI分别使用钆喷酸葡胺（Gd-DOTA，每千克200 μmol钆）和超小超顺磁性氧化铁（USPIO，每千克200 μmol铁）。C6和RG2胶质瘤对Gd-DOTA的通透性相同，但血容量分数和VSI不同，这与组织学数据高度一致。USPIO的存在使Ktrans值降低。在不存在和存在USPIO的情况下，用Gd-DOTA获得的C6胶质瘤Ktrans值具有良好的相关性，但RG2胶质瘤并非如此。还观察到，在DCE MRI的时间范围内，USPIO在C6胶质瘤中保持在血管内，而在RG2胶质瘤中则发生外渗。总之，只要USPIO在DCE MRI实验的时间范围内不发生外渗，VSI和DCE MRI就可以联合使用。USPIO外渗的起源机制仍有待阐明。
