Swanson Scott D, Dou Chunyan, Miller Douglas L
Department of Radiology, University of Michigan, Ann Arbor, 48109, USA.
Magn Reson Imaging. 2006 Jun;24(5):603-9. doi: 10.1016/j.mri.2005.12.014. Epub 2006 Feb 20.
The extent and magnitude of microvascular leakage induced by myocardial contrast echocardiography (MCE) were characterized with contrast-aided magnetic resonance imaging (MRI). Evans blue dye, Definity ultrasound contrast agent and Omniscan magnetic resonance contrast agent were injected intravenously in anesthetized rats suspended in a water bath. Diagnostic ultrasound B mode scans with 1:4 end-systolic triggering were performed at 1.5 MHz using a cardiac phased array scanhead to provide a short axis view of the left ventricle. The in situ peak rarefactional pressure amplitude (PRPA) was 2.0 MPa. Microvascular leakage was characterized by extraction of the dye from tissue samples and by imaging the distribution and concentration of Omniscan within the myocardium. The extracted Evans blue was 2.3 times greater than in shams (P<.05) for heart samples perfused with heparin saline, and 1.6 times greater than shams (not significant) for unperfused samples. The MRI showed the penetration of the ultrasound-induced capillary leakage throughout much of the scan plane. The overall gadolinium content measured by MR showed the same trends as the extracted Evans blue, but was more variable. For pooled data (perfused and unperfused), the exposed samples were significantly increased (P<.05) relative to the sham samples for both Evans blue and gadolinium content. Omniscan leakage was also discernable in two of four MRIs from intact rats (after sacrifice). These results demonstrate a potential for MR mapping of capillary leakage induced by contrast-aided ultrasound, with a possible application to spatial characterization of local drug delivery.
采用对比增强磁共振成像（MRI）对心肌对比超声心动图（MCE）诱导的微血管渗漏的范围和程度进行了表征。将伊文思蓝染料、Definity超声造影剂和Omniscan磁共振造影剂静脉注射到悬浮于水浴中的麻醉大鼠体内。使用心脏相控阵扫描头在1.5 MHz频率下进行1:4收缩末期触发的诊断性超声B模式扫描，以提供左心室的短轴视图。原位峰值稀疏压力振幅（PRPA）为2.0 MPa。通过从组织样本中提取染料以及对心肌内Omniscan的分布和浓度进行成像来表征微血管渗漏。对于用肝素盐水灌注的心脏样本，提取的伊文思蓝比假手术组高2.3倍（P<0.05），对于未灌注样本，比假手术组高1.6倍（无统计学意义）。MRI显示超声诱导的毛细血管渗漏贯穿整个扫描平面的大部分区域。通过MR测量的总体钆含量显示出与提取的伊文思蓝相同的趋势，但变异性更大。对于汇总数据（灌注和未灌注），无论是伊文思蓝含量还是钆含量，暴露样本相对于假手术样本均显著增加（P<0.05）。在处死的完整大鼠的四张MRI中的两张中也可观察到Omniscan渗漏。这些结果表明，对比增强超声诱导的毛细血管渗漏的MR成像具有潜力，可能应用于局部药物递送的空间表征。
