Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA.
Acad Radiol. 2011 Jul;18(7):866-75. doi: 10.1016/j.acra.2011.02.012.
Small metallic stents are increasingly used in the treatment of cerebral aneurysms and for revascularization in ischemic strokes. Realistic three-dimensional datasets of a stent were obtained by using three x-ray-based imaging methods in current clinical use. Multislice-CT (MS-CT), C-arm flat detector-CT (C-arm CT, ACT), and flat panel-CT (FP-CT) were compared with high-resolution laboratory MicroCT scans that served as a reference standard. The purpose was to assess and compare the quality and accuracy of current clinical three-dimensional reconstructions of a vascular stents.
MATERIAL & METHODS: A 3 × 20 mm Cypher stent was deployed in a straight polytetrafluoroethylene tube and filled with nondiluted iodine contrast and BaSO(4). MS-CT images of the static tube phantom and stent were acquired using GE LightSpeed VCT Series, C-arm CT images were obtained using Artis (DynaCT, Siemens), FP-CT were obtained using a preclinical research CT (GE), and MicroCT images were obtained using eXplore Locus SP (GE). DICOM datasets were analyzed using Amira and Matlab.
Because of blooming effects, the maximum intensity projections (MIPs) and volume renderings generated from MS-CT showed significantly increased strut dimensions with no distinction between the regular struts and connector struts while the lumen diameter is artificially reduced. The shape of the reconstructed stent surface differed remarkably from the real stent. C-arm CT and FP-CT volume renderings more accurately represented the struts. Consistently capturing the structure of the connectors and the strut shape definition was highly threshold dependent. The stent lumen was about 30% underestimated by MS-CT when compared to MicroCT.
The spatial resolution of current clinical CT for imaging of small metallic stents is insufficient to visualize fine geometrical details. Further improvement in the spatial resolution of clinical imaging technologies combined with better software and hardware for image postprocessing will be necessary for detailed structural analysis, evaluation of the stent lumen in vivo, and to permit accurate assessment of stent patency and early detection potential in-stent stenosis.
小型金属支架越来越多地用于治疗脑动脉瘤和缺血性中风再通。目前，使用三种基于 X 射线的成像方法获得了支架的真实三维数据集。多排 CT（MS-CT）、C 臂平板探测器 CT（C-arm CT，ACT）和平板探测器 CT（FP-CT）与高分辨率实验室 MicroCT 扫描进行了比较，后者作为参考标准。目的是评估和比较当前临床三维重建血管支架的质量和准确性。
将 3×20mm 的 Cypher 支架放置在直的聚四氟乙烯管中，并充满未稀释的碘造影剂和 BaSO4。使用 GE LightSpeed VCT 系列获取静态管体模型和支架的 MS-CT 图像，使用 Artis（DynaCT，西门子）获取 C 臂 CT 图像，使用临床前研究 CT（GE）获取 FP-CT，使用 eXplore Locus SP（GE）获取 MicroCT 图像。使用 Amira 和 Matlab 分析 DICOM 数据集。
由于blooming 效应，MS-CT 生成的最大强度投影（MIP）和容积渲染图显示支架的尺寸明显增加，且无法区分规则支架和连接支架，而管腔直径被人为减小。重建支架表面的形状与真实支架明显不同。C 臂 CT 和 FP-CT 容积渲染图更准确地表示了支架的结构。一致地捕获连接结构和支架形状定义高度依赖于阈值。与 MicroCT 相比，MS-CT 低估了支架管腔约 30%。
目前用于小金属支架成像的临床 CT 的空间分辨率不足以显示精细的几何细节。为了进行详细的结构分析、评估体内支架管腔以及允许对支架通畅性进行准确评估和早期检测潜在的支架内狭窄，需要进一步提高临床成像技术的空间分辨率，并结合更好的软件和硬件进行图像处理。
