Sipilä Outi, Blomqvist Päivi, Jauhiainen Mervi, Kilpeläinen Tiina, Malaska Paula, Mannila Vilma, Vinnurva-Jussila Tuula, Virsula Sari
HUS Helsinki Medical Imaging Center, Meilahti Hospital, Helsinki University Central Hospital, Helsinki, Finland.
Acta Radiol. 2011 Jul 1;52(6):665-9. doi: 10.1258/ar.2011.100227. Epub 2011 Apr 20.
In a large radiological center, the ultrasound (US) quality assurance (QA) program involves several professionals. Although the operator and the parameters utilized can contribute to the results, the selected QA parameters should still reflect the quality of the US scanner, not the measuring process.
To evaluate the reproducibility of recommended phantom-based US QA parameters in a realistic environment.
Six sonographers measured six high-end US scanners with 20 transducers using a general purpose phantom. Every transducer was measured altogether seven times, using one frequency per transducer. The QA parameters studied were homogeneity, visualization depth, vertical and horizontal distance measurements, axial and lateral resolution, and the correct visibility of anechoic and high-contrast masses. The evaluation of the homogeneity was based on visual observations. Inter-observer interquartile ranges were computed for the grading of the masses. For the other QA parameters, the mean inter- and intra-observer coefficients of variation (CoV) were calculated. In addition, the symmetry of the reverberations when imaging air with a clean transducer was checked.
The mean inter-observer CoVs were: visualization depth 11 ± 4%, vertical distance 1.7 ± 0.4%, horizontal distance 1.4 ± 0.6%, axial resolution 22 ± 7%, and lateral resolution 16 ± 8%. The mean intra-observer values were about half of these values with similar standard deviations. The visual evaluation of the homogeneity and the symmetry of the reverberations produced false-positive findings in 5% of the cases, but were found useful in detecting a defective transducer. The grading of the masses had mean interquartile ranges of 20-30% of the grading scale.
The inter-observer variability in measuring phantom-based QA parameters can be relatively high. This should be considered when implementing a phantom-based QA protocol and evaluating the results.
在一个大型放射中心，超声（US）质量保证（QA）计划涉及多名专业人员。尽管操作员和所使用的参数会对结果产生影响，但所选的QA参数仍应反映US扫描仪的质量，而非测量过程。
在实际环境中评估基于体模的推荐US QA参数的可重复性。
六名超声检查医师使用通用体模，用20个换能器对六台高端US扫描仪进行测量。每个换能器总共测量七次，每个换能器使用一个频率。所研究的QA参数包括均匀性、可视化深度、垂直和水平距离测量、轴向和侧向分辨率，以及无回声和高对比度肿块的正确可见性。均匀性评估基于视觉观察。计算观察者间四分位间距以对肿块进行分级。对于其他QA参数，计算观察者间和观察者内变异系数（CoV）的平均值。此外，检查使用清洁换能器对空气成像时混响的对称性。
观察者间CoV的平均值为：可视化深度11±4%，垂直距离1.7±0.4%，水平距离1.4±0.6%，轴向分辨率22±7%，侧向分辨率16±8%。观察者内平均值约为这些值的一半，标准差相似。均匀性的视觉评估和混响的对称性在5%的病例中产生了假阳性结果，但被发现有助于检测有缺陷的换能器。肿块分级的平均四分位间距为分级量表的20 - 30%。
基于体模的QA参数测量中观察者间的变异性可能相对较高。在实施基于体模的QA方案和评估结果时应考虑这一点。
