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首页> 外文学位 >Validation of time-resolved Digital Subtraction Angiography using patient specific 3D printed neurovascular phantoms.
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Validation of time-resolved Digital Subtraction Angiography using patient specific 3D printed neurovascular phantoms.

机译：使用患者特定的3D打印的神经血管幻象验证时间分辨的数字减影血管造影术。

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摘要

Digital Subtraction Angiography (DSA) is a standard golden tool for interventional radiology to clearly visualize blood vessels in a bony or dense tissue environment. Time-resolved DSA, also known as color-coded DSA or Parametric Imaging (PI), is a semi-quantitative tool giving temporal blood flow information. It generates a Time Density Curve (TDC), to give PI parameters -- Bolus Arrival Time (BAT), Time to Peak (TTP) and Mean Transit Time (MTT). It can be a useful tool for vascular disease diagnosis and post-treatment analysis in a clinical environment. PI was validated using 3 major steps: 1) validation at very low mA (tube current) and exposure levels, 2) comparing the parameters of PI with velocities obtained from Doppler ultrasound and 3) obtaining 4D PI maps using 2D PI maps co-registered on a 3D vascular geometry to overcome the problem of incorrect PI parameters at regions of vessel overlap.;In order to validate PI, we 3D printed patient specific neurovascular phantoms of the complete Circle of Willis, from a patient CT volume. These phantoms were connected to a flow loop containing a peristaltic pump, pumping fluid at various flow rates, simulating physiological flow conditions. To obtain the DSA images, the phantoms were also connected to an automatic contrast injector injecting contrast boluses at 10 ml/sec. The water pumped through the phantoms was not recirculated to prevent contrast contamination. The DSA images were obtained using the Toshiba Infinix Angio C-arm.;To obtain the Doppler Ultrasound velocities, the phantoms were embedded in Ballistic gel. Doppler Ultrasound velocities were obtained using the Toshiba Aplio XG Ultrasound system and blood mimicking fluid was pumped through the phantoms. The DSA images were obtained as in Step 1 and saved in '.raw' format. The DSA sequence was input into an in-house developed LabVIEW software to obtain the 2D parametric maps.;For the 4D PI maps, we made use of a Computed Tomography (CT) volume using only a single Cone Beam Computed Tomography (CBCT) acquisition and co-registering the 2D Parametric maps on the 3D vascular CT volume with regions of vessel overlap were spline interpolated from regions of no vessel overlap. An in-house developed LabVIEW software was used to obtain the 4D PI maps.;Results:.;The results of the PI maps obtained for each of the steps (1-2) were compared to a PI map at optimal conditions. For Step 1 at low Signal to Noise Ratio (SNR) at low x-ray exposures, the results showed minimal standard variation in SNR in the bigger arteries (high SNR), however there was a greater standard variation in SNR in the smaller arteries due to low SNR.;For Step 2, for an increase in Doppler ultrasound velocity there was a decrease in the PI parameters. This is in good correlation to the fact that an increase in blood velocity will decrease the time taken to flow through the blood vessels.;For Step 3, the 4D PI maps obtained overcame the problem of vessel overlap in standard 2D PI maps. At the regions of vessel overlap, interpolation helped in getting rid of higher PI Parameter values due to higher contrast density.
机译：数字减影血管造影（DSA）是用于介入放射学的标准黄金工具，可以清楚地观察骨骼或致密组织环境中的血管。时间分辨DSA，也称为颜色编码DSA或参数成像（PI），是一种半定量工具，可提供时间血流信息。它会生成一个时间密度曲线（TDC），以提供PI参数-到达时间（BAT），到达峰时间（TTP）和平均通过时间（MTT）。在临床环境中，它可能是用于血管疾病诊断和治疗后分析的有用工具。使用以下3个主要步骤对PI进行了验证：1）在非常低的mA（管电流）和暴露水平下进行验证； 2）比较PI的参数与从多普勒超声获得的速度； 3）使用共同注册的2D PI图获得4D PI图在3D血管几何结构上克服了PI在血管重叠区域的参数不正确的问题。为了验证PI，我们从患者CT体积中3D打印了完整Willis环的患者特定神经血管模型。这些体模连接到包含蠕动泵的流动回路，以各种流速泵送流体，模拟生理流动条件。为了获得DSA图像，还将体模连接到以10 ml / sec的速度注入造影剂的自动造影剂注射器。通过体模泵送的水不进行再循环以防止对比剂污染。使用Toshiba Infinix Angio C臂获得DSA图像。为了获得多普勒超声速度，将体模嵌入到Ballistic凝胶中。使用Toshiba Aplio XG Ultrasound系统获得多普勒超声速度，并将血液模拟液泵送通过体模。如步骤1中所述获得DSA图像，并以“ .raw”格式保存。将DSA序列输入到内部开发的LabVIEW软件中以获得2D参数图;对于4D PI图，我们仅使用一次锥形束计算机断层扫描（CBCT）采集就使用了计算机断层扫描（CT）体并从没有血管重叠的区域进行样条插值，并在3D血管CT体积与血管重叠区域上共同注册2D参数图。使用内部开发的LabVIEW软件获取4D PI图。结果：将在每个步骤（1-2）中获得的PI图的结果与最佳条件下的PI图进行比较。对于低x射线照射下低信噪比（SNR）的第1步，结果显示较大动脉中SNR的标准偏差最小（高SNR），但是由于较小动脉中SNR的标准偏差较大到低SNR 。；对于步骤2，随着多普勒超声速度的增加，PI参数降低。这与以下事实高度相关：血流速度的增加将减少流过血管所需的时间。对于步骤3，获得的4D PI映射克服了标准2D PI映射中的血管重叠问题。在血管重叠区域，由于较高的对比度密度，插值有助于消除较高的PI参数值。

著录项

  • 作者

    Balasubramoniam, Anusha.;

  • 作者单位

    State University of New York at Buffalo.;

  • 授予单位 State University of New York at Buffalo.;
  • 学科 Biomedical engineering.;Medical imaging.
  • 学位 M.S.
  • 年度 2016
  • 页码 72 p.
  • 总页数 72
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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