Schmitz S A, Winterhalter S, Schiffler S, Gust R, Wagner S, Kresse M, Coupland S E, Semmler W, Wolf K J
Department of Radiology and Nuclear Medicine, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Hindenburgdamm 30, 12200 Berlin, Germany.
Radiology. 2001 Oct;221(1):237-43. doi: 10.1148/radiol.2211001632.
To test the hypothesis that ultrasmall superparamagnetic iron oxide (USPIO) particles may diffuse into nonendothelialized fresh thrombi and thus allow for direct magnetic resonance (MR) imaging of a thrombus.
Stagnation thrombi of different thrombus ages (1, 3, 5, 7, and 9 days) were induced in the external jugular veins of 25 rabbits. Direct MR imaging of thrombi was performed by using a fat-saturated T1-weighted gradient-echo sequence (three-dimensional [3D] magnetization prepared rapid acquisition gradient echo) before and 24 hours after intravenous administration of USPIO (particle size, 25 nm; 200 micromol per kilogram of body weight). Thrombus length on 3D reconstruction images was compared with that depicted on a radiographic venogram and with histologic findings (joint reference standard). In addition, T2*-weighted gradient-echo images were acquired and scored semiquantitatively.
The hyperintensity of the thrombus segment depicted on T1-weighted images (thrombus length determined with 3D reconstruction images divided by true thrombus length) increased significantly after administration of contrast medium at a thrombus age of 3 days (0.6 +/- 0.4 [SD] to 0.8 +/- 0.4; P =.02), 5 days (0.1 +/- 0.1 to 1.0 +/- 0.1; P <.001), and 7 days (0 to 0.6 +/- 0.4; P =.02), but not at an age of 1 and 9 days. No significant change in the thrombus signal intensity was observed on T2*-weighted images.
The animal model showed that direct MR imaging of the thrombus improved 24 hours after USPIO administration with a T1-weighted sequence. No improvement was seen with the T2*-weighted sequence.
验证超小超顺磁性氧化铁（USPIO）颗粒可能扩散至未内皮化的新鲜血栓中，从而实现血栓直接磁共振（MR）成像的假说。
在25只兔的颈外静脉中诱导形成不同血栓龄（1、3、5、7和9天）的淤滞性血栓。在静脉注射USPIO（粒径25 nm；200 μmol/kg体重）前及注射后24小时，采用脂肪饱和T1加权梯度回波序列（三维[3D]磁化准备快速采集梯度回波）对血栓进行直接MR成像。将3D重建图像上的血栓长度与静脉造影显示的血栓长度以及组织学结果（联合参考标准）进行比较。此外，采集T2*加权梯度回波图像并进行半定量评分。
在血栓龄为3天（0.6±0.4[标准差]至0.8±0.4；P = 0.02）、5天（0.1±0.1至1.0±0.1；P < 0.001）和7天（0至0.6±0.4；P = 0.02）时，注射造影剂后T1加权图像上显示的血栓节段高信号强度（用3D重建图像确定的血栓长度除以真实血栓长度）显著增加，但在血栓龄为1天和9天时未增加。T2*加权图像上未观察到血栓信号强度的显著变化。
动物模型显示，注射USPIO后24小时，采用T1加权序列可改善血栓的直接MR成像。T2*加权序列未见改善。
