Pullens Pim, Bladt Piet, Sijbers Jan, Maas Andrew I R, Parizel Paul M
Department of Radiology, University Hospital Antwerp & University of Antwerp, 2650, Edegem, Belgium.
iMinds - Vision Lab, Department of Physics, University of Antwerp, 2610, Antwerp, Belgium.
Med Phys. 2017 Mar;44(3):1063-1070. doi: 10.1002/mp.12101. Epub 2017 Feb 28.
Since Diffusion Weighted Imaging (DWI) data acquisition and processing are not standardized, substantial differences in DWI derived measures such as Apparent Diffusion Coefficient (ADC) may arise which are related to the acquisition or MRI processing method, but not to the sample under study. Quality assurance using a standardized test object, or phantom, is a key factor in standardizing DWI across scanners.
Current diffusion phantoms are either complex to use, not available in larger quantities, contain substances unwanted in a clinical environment, or are expensive. A diffusion phantom based on a polyvinylpyrrolidone (PVP) solution, together with a phantom holder, is presented and compared to existing diffusion phantoms for use in clinical DWI scans. An ADC vs. temperature calibration curve was obtained.
ADC of the phantom (808 to 857 ± 0.2 mm /s) is in the same range as ADC values found in brain tissue. ADC measurements are highly reproducible across time with an intra-class correlation coefficient of > 0.8. ADC as function of temperature (in Kelvin) can be estimated as ADCm(T)=[exp(-7.09)·exp-2903.81T-1293.55] with a total uncertainty (95% confidence limit) of ± 1.7%.
We present an isotropic diffusion MRI phantom, together with its temperature calibration curve, that is easy-to-use in a clinical environment, cost-effective, reproducible to produce, and that contains no harmful substances.
由于扩散加权成像（DWI）数据采集和处理未标准化，DWI衍生测量值（如表观扩散系数（ADC））可能会出现显著差异，这些差异与采集或MRI处理方法有关，而非与所研究的样本有关。使用标准化测试对象或体模进行质量保证是使各扫描仪的DWI标准化的关键因素。
目前的扩散体模要么使用复杂，无法大量获取，含有临床环境中不需要的物质，要么价格昂贵。本文介绍了一种基于聚乙烯吡咯烷酮（PVP）溶液的扩散体模及其体模支架，并将其与现有的用于临床DWI扫描的扩散体模进行比较。获得了ADC与温度的校准曲线。
体模的ADC（808至857±0.2mm²/s）与脑组织中的ADC值处于同一范围。ADC测量在不同时间具有高度可重复性，组内相关系数>0.8。ADC作为温度（开尔文）的函数可估计为ADCm(T)=[exp(-7.09)·exp-2903.81T-1293.55]，总不确定度（95%置信限）为±1.7%。
我们展示了一种各向同性扩散MRI体模及其温度校准曲线，其在临床环境中易于使用，具有成本效益，生产可重复，且不含有有害物质。
