磁共振成像采集加速通过压缩感知和并行成像对脑容量测量的影响。
Effect of MRI acquisition acceleration via compressed sensing and parallel imaging on brain volumetry.
机构信息
Department of Diagnostic and Interventional Neuroradiology, Klinikum Rechts Der Isar der Technischen Universität München, Ismaninger Str. 22, 81675, Munich, Germany.
Lab for Artificial Intelligence in Medical Imaging, Klinik und Poliklinik Für Kinder- und Jugendpsychiatrie, Psychosomatik und Psychotherapie, Klinikum der Universität München, LMU München, Waltherstr. 23, 80337, Munich, Germany.
出版信息
MAGMA. 2021 Aug;34(4):487-497. doi: 10.1007/s10334-020-00906-9. Epub 2021 Jan 27.
OBJECTIVES
To investigate the effect of compressed SENSE (CS), an acceleration technique combining parallel imaging and compressed sensing, on potential bias and precision of brain volumetry and evaluate it in the context of normative brain volumetry.
MATERIALS AND METHODS
In total, 171 scans from scan-rescan experiments on three healthy subjects were analyzed. Each subject received 3D-T1-weighted brain MRI scans at increasing degrees of acceleration (CS-factor = 1/4/8/12/16/20/32). Single-scan acquisition times ranged from 00:41 min (CS-factor = 32) to 21:52 min (CS-factor = 1). Brain segmentation and volumetry was performed using two different software tools: md.brain, a proprietary software based on voxel-based morphometry, and FreeSurfer, an open-source software based on surface-based morphometry. Four sub-volumes were analyzed: brain parenchyma (BP), total gray matter, total white matter, and cerebrospinal fluid (CSF). Coefficient of variation (CoV) of the repeated measurements as a measure of intra-subject reliability was calculated. Intraclass correlation coefficient (ICC) with regard to increasing CS-factor was calculated as another measure of reliability. Noise-to-contrast ratio as a measure of image quality was calculated for each dataset to analyze the association between acceleration factor, noise and volumetric brain measurements.
RESULTS
For all sub-volumes, there is a systematic bias proportional to the CS-factor which is dependent on the utilized software and subvolume. Measured volumes deviated significantly from the reference standard (CS-factor = 1), e.g. ranging from 1 to 13% for BP. The CS-induced systematic bias is driven by increased image noise. Except for CSF, reliability of brain volumetry remains high, demonstrated by low CoV (< 1% for CS-factor up to 20) and good to excellent ICC for CS-factor up to 12.
CONCLUSION
CS-acceleration has a systematic biasing effect on volumetric brain measurements.
目的
研究压缩敏感（CS）加速技术（将并行成像与压缩感知相结合）对脑容量潜在偏倚和精度的影响，并在规范脑容量的背景下对其进行评估。
材料与方法
总共对 3 名健康受试者的扫描-扫描实验中的 171 个扫描进行了分析。每位受试者均接受了在不同加速程度（CS 因子=1/4/8/12/16/20/32）下的 3D-T1 加权脑 MRI 扫描。单扫描采集时间范围为 00:41 分钟（CS 因子=32）至 21:52 分钟（CS 因子=1）。使用两种不同的软件工具进行脑分割和容积测量：md.brain，基于体素的形态计量学的专有的软件；FreeSurfer，基于表面形态计量学的开源软件。分析了四个子容积：脑实质（BP）、总灰质、总白质和脑脊液（CSF）。以重复测量的变异系数（CoV）作为个体内可靠性的衡量标准。还计算了随着 CS 因子的增加，与 CS 因子相关的组内相关系数（ICC），作为另一种可靠性衡量标准。为分析加速因子、噪声与脑容积测量之间的关系，为每个数据集计算了噪声与对比比作为图像质量的衡量标准。
结果
对于所有子容积，均存在与 CS 因子成比例的系统偏差，该偏差取决于所使用的软件和子容积。与参考标准（CS 因子=1）相比，测量体积明显存在偏差，例如 BP 范围为 1%至 13%。CS 引起的系统偏差是由图像噪声增加引起的。除 CSF 外，脑容积测量的可靠性仍然很高，CS 因子高达 20 时 CoV 较低（<1%），CS 因子高达 12 时 ICC 较好至极好。
结论
CS 加速对脑容量测量有系统的偏倚影响。
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