Dousset V, Ballarino L, Delalande C, Coussemacq M, Canioni P, Petry K G, Caillé J M
Laboratoire de NeuroBiologie et NeuroImagerie Expérimentales, Université Victor Segalen Bordeaux2, France.
AJNR Am J Neuroradiol. 1999 Feb;20(2):223-7.
Ultrasmall particles of iron oxide (USPIO) constitute a contrast agent that accumulates in cells from the mononuclear phagocytic system. In the CNS they may accumulate in phagocytic cells such as macrophages. The goal of this study was to compare USPIO-enhanced MR images with conventional T2-weighted images and gadolinium-enhanced T1-weighted images in a model of experimental autoimmune encephalomyelitis (EAE).
Nine rats with EAE and four control rats were imaged at 4.7 T and 1.5 T with conventional T1- and T2-weighted sequences, gadolinium-enhanced T1-weighted sequences, and T2-weighted sequences obtained 24 hours after intravenous injection of a USPIO contrast agent, AMI-227. Histologic examination was performed with hematoxylin-eosin stain, Perls' stain for iron, and ED1 immunohistochemistry for macrophages.
USPIO-enhanced images showed a high sensitivity (8/9) for detecting EAE lesions, whereas poor sensitivity was obtained with T2-weighted images (1/9) and gadolinium-enhanced T1-weighted images (0/9). All the MR findings in the control rats were negative. Histologic examination revealed the presence of macrophages at the site where abnormalities were seen on USPIO-enhanced images.
The high sensitivity of USPIO for macrophage activity relative to other imaging techniques is explained by the histologic findings of numerous perivascular cell infiltrates, including macrophages, in EAE. This work supports the possibility of intracellular USPIO transport to the CNS by monocytes/macrophages, which may have future implications for imaging of human inflammatory diseases.
超小超顺磁性氧化铁颗粒（USPIO）是一种造影剂，可在单核吞噬系统的细胞中蓄积。在中枢神经系统中，它们可能蓄积于吞噬细胞如巨噬细胞内。本研究的目的是在实验性自身免疫性脑脊髓炎（EAE）模型中，比较USPIO增强磁共振成像与传统T2加权成像及钆增强T1加权成像。
对9只患EAE的大鼠和4只对照大鼠分别在4.7 T和1.5 T磁场下，采用传统T1加权和T2加权序列、钆增强T1加权序列以及静脉注射USPIO造影剂AMI - 227后24小时获得的T2加权序列进行成像。采用苏木精 - 伊红染色、Perls铁染色以及巨噬细胞ED1免疫组化进行组织学检查。
USPIO增强图像对检测EAE病变具有较高的敏感性（8/9），而T2加权图像（1/9）和钆增强T1加权图像（0/9）的敏感性较差。对照大鼠的所有磁共振成像结果均为阴性。组织学检查显示，在USPIO增强图像上出现异常的部位存在巨噬细胞。
相对于其他成像技术，USPIO对巨噬细胞活性具有较高的敏感性，这可以通过EAE中包括巨噬细胞在内的大量血管周围细胞浸润的组织学发现来解释。这项工作支持单核细胞/巨噬细胞将细胞内USPIO转运至中枢神经系统的可能性，这可能对人类炎症性疾病的成像具有未来意义。
