Wang Maisie S, Haynor David R, Wilson Gregory J, Maki Jeffrey H
Department of Bioengineering, University of Washington, Seattle, Washington 98195-5061, USA.
J Magn Reson Imaging. 2006 Dec;24(6):1393-400. doi: 10.1002/jmri.20773.
To evaluate intravenous hematocrit (HCT) layering detected in patent calf veins that potentially simulate filling defects seen in deep venous thrombosis (DVT).
Flow characteristics, vessel size, and enhancement patterns of veins with HCT layering were examined and compared with those of normal veins in vivo. Ex vivo studies were conducted with conventional and blood pool contrast agents to study the effects of MRI parameters and intrinsic variables on detecting HCT layering.
HCT layering was detected in high resolution equilibrium phase images in one of six healthy subjects, and five of five patients with peripheral vascular occlusive disease (PVOD). Layering occurred only in deep veins that had significantly slower flow and larger diameter (P < 0.001) compared to normal veins. Enhancement patterns observed in vivo were similar to those found in the ex vivo study.
The HCT layering effect in MR venography has not been previously reported, likely because delayed equilibrium phase venous imaging is not frequently performed. The use of blood pool contrast agents and high resolution equilibrium phase imaging allows intravascular HCT layering to be observed within a 30-60-minute time frame. Several imaging characteristics that distinguish HCT layering from DVT are discussed.
评估在正常小腿静脉中检测到的静脉血细胞比容（HCT）分层，其可能模拟深静脉血栓形成（DVT）中所见的充盈缺损。
对存在HCT分层的静脉的血流特征、血管大小及强化模式进行检查，并与体内正常静脉的这些特征进行比较。使用传统造影剂和血池造影剂进行体外研究，以探讨MRI参数和内在变量对检测HCT分层的影响。
在6名健康受试者中的1名以及5名外周血管闭塞性疾病（PVOD）患者中的5名的高分辨率平衡期图像中检测到HCT分层。分层仅发生在与正常静脉相比血流明显更慢且直径更大的深静脉中（P < 0.001）。体内观察到的强化模式与体外研究中发现的相似。
MR静脉造影中的HCT分层效应此前未见报道，可能是因为平衡期静脉延迟成像不常进行。使用血池造影剂和高分辨率平衡期成像可在30至60分钟的时间范围内观察到血管内HCT分层。讨论了一些将HCT分层与DVT区分开来的成像特征。
