Medical Ultrasound Physics and Technology Group, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland.
Med Phys. 2011 Feb;38(2):565-73. doi: 10.1118/1.3533674.
A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease.
The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed for use with ultrasound, magnetic resonance imaging, x-ray computed tomography, and x-ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry (T1, T2) properties, and Hounsfield number/x-ray attenuation coefficient, with a design capable of tolerating high-pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions.
High quality distortion-free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher-stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA.
The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast to allow for quantitative measurements of the degree of stenosis in each phantom. Such multimodality phantoms may prove useful in evaluating current and emerging US, MRI, CT, and DSA technology.
本研究开发并评估了一系列具有不同狭窄程度的解剖逼真的多模态肾动脉模型，这些模型使用目前用于检测肾动脉狭窄（RAS）的四种成像技术。目前，可视化血管几何形状所需的空间分辨率以及充分描述 RAS 患者血流特征所需的速度检测性能尚未明确，因此没有一种成像方式成为筛查该疾病的金标准技术。
这些模型包含了一系列狭窄值（0%、30%、50%、70%和 85%），旨在与超声、磁共振成像、X 射线计算机断层扫描和 X 射线数字减影血管造影等技术配合使用。所用的构建材料在超声声速和衰减系数、磁共振弛豫度（T1、T2）特性和亨氏单位/ X 射线衰减系数方面进行了优化，设计能够耐受高压脉动流。为了使不同模式之间的图像能够配准，在模型中加入了基准目标，以尽量减少几何变形。
通过每一种模式都能获得高质量、无失真的图像，这些图像具有良好的对比度，可以清晰显示所有狭窄部位，以及血管内腔、基准标记和背景组织之间的对比度。对狭窄程度的定量评估显示，各模式之间存在显著差异，对于较高狭窄程度的模型（70%和 85%），每种模式都低估了狭窄的严重程度，最大的差异归因于 DSA。
本研究描述了一系列具有不同狭窄程度的解剖逼真的肾动脉模型的设计和构建。使用主要的四种用于检测 RAS 的诊断技术获得的图像无伪影，并且对比度充足，能够对每个模型中的狭窄程度进行定量测量。这种多模态模型可能有助于评估当前和新兴的超声、磁共振成像、CT 和 DSA 技术。
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