MRI quality assurance using the ACR phantom in a multi-unit imaging center
MRI quality assurance using the ACR phantom in a multi-unit imaging center
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DOI：
10.3109/0284186x.2011.582515
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发表时间：
2011-08-01
期刊：
影响因子：
3.1
通讯作者：
Sipila, Outi E.
中科院分区：
文献类型：
--
作者：
Ihalainen, Toni M.;Lonnroth, Nadja T.;Sipila, Outi E.
背景。磁共振成像（MRI）仪器容易受到技术和图像质量问题的影响，质量保证至关重要。在研究的区域成像中心，长期的质量保证是基于磁模测量。美国放射学会（ACR）有一个认证项目，包括标准化的图像质量测量协议和幻影。ACR方案包括临床序列的推荐接受标准，从而提供了评估质量保证的临床相关性的可能性。本研究的目的是在多单元成像中心测试ACR MRI幻像的质量保证。材料和方法。成像中心使用三家主要制造商的11台MRI系统，场强分别为3.0 T、1.5 T和1.0 T，根据ACR扫描说明使用头线圈获得ACR幻影的图像。获得ACR T1和t2加权序列以及临床使用的每个部位的T1和t2加权脑序列。测量进行了两次。对图像进行分析，并将结果与ACR可接受水平进行比较。结果。ACR幻影的获取过程比MagNET幻影的获取过程要快。在第一轮和第二轮测试中，91%和73%的系统通过了ACR测试。测量的切片厚度精度不在T2序列的可接受范围内。观察到ACR和位点序列在高对比度空间分辨率上的差异。在3.0 T系统中，图像强度均匀性略低于ACR接受极限。结论。ACR方法在多单元成像中心的质量保证中是可行的，ACR方案可以替代磁体模拟试验。图像的自动分析将进一步提高ACR协议的成本效益和客观性。
Background. Magnetic resonance imaging (MRI) instrumentation is vulnerable to technical and image quality problems, and quality assurance is essential. In the studied regional imaging center the long-term quality assurance has been based on MagNET phantom measurements. American College of Radiology (ACR) has an accreditation program including a standardized image quality measurement protocol and phantom. The ACR protocol includes recommended acceptance criteria for clinical sequences and thus provides possibility to assess the clinical relevance of quality assurance. The purpose of this study was to test the ACR MRI phantom in quality assurance of a multi-unit imaging center. Material and methods. The imaging center operates 11 MRI systems of three major manufacturers with field strengths of 3.0 T, 1.5 T and 1.0 T. Images of the ACR phantom were acquired using a head coil following the ACR scanning instructions. Both ACR T1- and T2-weighted sequences as well as T1- and T2-weighted brain sequences in clinical use at each site were acquired. Measurements were performed twice. The images were analyzed and the results were compared with the ACR acceptance levels. Results. The acquisition procedure with the ACR phantom was faster than with the MagNET phantoms. On the first and second measurement rounds 91% and 73% of the systems passed the ACR test. Measured slice thickness accuracies were not within the acceptance limits in site T2 sequences. Differences in the high contrast spatial resolution between the ACR and the site sequences were observed. In 3.0 T systems the image intensity uniformity was slightly lower than the ACR acceptance limit. Conclusion. The ACR method was feasible in quality assurance of a multi-unit imaging center and the ACR protocol could replace the MagNET phantom tests. An automatic analysis of the images will further improve cost-effectiveness and objectiveness of the ACR protocol.