Rajan Sunder, Herbertson Luke, Bernardo Marcelino, Choyke Peter
Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, FDA, Silver Spring, Maryland, USA.
Magn Reson Med. 2014 Jul;72(1):41-8. doi: 10.1002/mrm.24887. Epub 2013 Jul 31.
Dynamic contrast enhanced magnetic resonance imaging (MRI) has proven to be quite sensitive for the characterization of masses and early response to therapy. However, it is fraught with a number of procedural challenges as well as a lack of standardization. In this article, we describe the use of a simple dialyzer-based flow system to evaluate reproducibility of dynamic contrast enhanced MRI under active flow conditions.
The MR signal during a bolus injection of Gd-DTPA was analyzed to test the precision and variability of contrast agent kinetics during a typical dynamic contrast enhanced MRI sequence. A simple model allows an estimation of the washout rate constant of Gd-DTPA through the polysulfone tubules of the dialyzer.
The simple flow phantom described here provided reproducible measurements of the washout rate constants. The washout rate increased from 0.20 ± 0.005 min(-1) to 0.25 ± 0.008 min(-1) over 32 weeks. Measurements were also made at week 24 using dynamic computed tomography and found to be 0.27 ± 0.006 min(-1) . Overall, the computed tomography derived rate constants results were found be ∼12% higher than the corresponding MRI values.
In this study, we show that a simple dialyzer-based flow phantom can be used for testing dynamic contrast enhanced MRI pulse sequences and also allows for short-term reproducibility testing of rate constants.
动态对比增强磁共振成像（MRI）已被证明在肿块特征描述和治疗早期反应方面相当敏感。然而，它面临着许多程序上的挑战以及缺乏标准化的问题。在本文中，我们描述了使用一种基于简单透析器的流动系统来评估动态对比增强MRI在主动流动条件下的可重复性。
分析注射钆喷酸葡胺（Gd-DTPA）团注期间的MR信号，以测试典型动态对比增强MRI序列中造影剂动力学的精度和变异性。一个简单的模型可以估计Gd-DTPA通过透析器聚砜小管的洗脱速率常数。
这里描述的简单流动模型提供了洗脱速率常数的可重复测量。在32周内，洗脱速率从0.20±0.005 min⁻¹增加到0.25±0.008 min⁻¹。在第24周还使用动态计算机断层扫描进行了测量，结果为0.27±0.006 min⁻¹。总体而言，计算机断层扫描得出的速率常数结果比相应的MRI值高约12%。
在本研究中，我们表明一种基于简单透析器的流动模型可用于测试动态对比增强MRI脉冲序列，并且还允许对速率常数进行短期可重复性测试。
