Yuan Jing, Xue Cindy, Lo Gladys, Wong Oi Lei, Zhou Yihang, Yu Siu Ki, Cheung Kin Yin
Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong, Hong Kong SAR, China.
Department of Diagnostic & Interventional Radiology, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong, Hong Kong SAR, China.
Quant Imaging Med Surg. 2021 May;11(5):1870-1887. doi: 10.21037/qims-20-865.
MRI pulse sequences and imaging parameters substantially influence the variation of MRI radiomics features, thus impose a critical challenge on MRI radiomics reproducibility and reliability. This study aims to prospectively investigate the impact of various imaging parameters on MRI radiomics features in a 3D T2-weighted (T2W) turbo-spin-echo (TSE) pulse sequence for MR-guided-radiotherapy (MRgRT).
An anthropomorphic phantom was scanned using a 3D-T2W-TSE MRgRT sequence at 1.5T under a variety of acquisition imaging parameter changes. T1 and T2 relaxation times of the phantom were also measured. 93 first-order and texture radiomics features in the original and 14 transformed images, yielding 1,395 features in total, were extracted from 10 volumes-of-interest (VOIs). The percentage deviation (d%) of radiomics feature values from the baseline values and intra-class correlation coefficient (ICC) with the baseline were calculated. Robust radiomics features were identified based on the excellent agreement of radiomics feature values with the baseline, i.e., the averaged d% <5% and ICC >0.90 in all VOIs for all imaging parameter variations.
The radiomics feature values changed considerably but to different degrees with different imaging parameter adjustments, in the ten VOIs. The deviation d% ranged from 0.02% to 321.3%, with a mean of 12.5% averaged for all original features in all ten VOIs. First-order and GLCM features were generally more robust to imaging parameters than other features in the original images. There were also significantly different radiomics feature values (ANOVA, P<0.001) between the original and the transformed images, exhibiting quite different robustness to imaging parameters. 330 out of 1395 features (23.7%) robust to imaging parameters were identified. GLCM and GLSZM features had the most (42.5%, 153/360) and least (3.8%, 9/240) robust features in the original and transformed images, respectively.
This study helps better understand the quantitative dependence of radiomics feature values on imaging parameters in a 3D-T2W-TSE sequence for MRgRT. Imaging parameter heterogeneity should be considered as a significant source of radiomics variability and uncertainty, which must be well harmonized for reliable clinical use. The identified robust features to imaging parameters are helpful for the pre-selection of radiomics features for reliable radiomics modeling.
MRI脉冲序列和成像参数对MRI影像组学特征的变化有重大影响，从而对MRI影像组学的可重复性和可靠性构成严峻挑战。本研究旨在前瞻性地研究在用于磁共振引导放射治疗（MRgRT）的三维T2加权（T2W）涡轮自旋回波（TSE）脉冲序列中，各种成像参数对MRI影像组学特征的影响。
使用三维T2W-TSE MRgRT序列在1.5T条件下，对一个仿真人体模型进行扫描，改变多种采集成像参数。同时测量该模型的T1和T2弛豫时间。从10个感兴趣体积（VOI）中提取原始图像和14幅变换图像中的93个一阶和纹理影像组学特征，共得到1395个特征。计算影像组学特征值相对于基线值的百分比偏差（d%）以及与基线的组内相关系数（ICC）。基于影像组学特征值与基线的高度一致性来识别稳健的影像组学特征，即在所有成像参数变化下，所有VOI中的平均d%<5%且ICC>0.90。
在十个VOI中，随着不同成像参数的调整，影像组学特征值有显著变化，但程度不同。偏差d%范围为0.02%至321.3%，所有十个VOI中所有原始特征的平均偏差为12.5%。在原始图像中，一阶和灰度共生矩阵（GLCM）特征通常比其他特征对成像参数更稳健。原始图像和变换图像之间的影像组学特征值也存在显著差异（方差分析，P<0.001），对成像参数的稳健性表现出很大不同。在1395个特征中，识别出330个（23.7%）对成像参数稳健的特征。在原始图像和变换图像中，GLCM和灰度行程长度矩阵（GLSZM）特征分别具有最多（42.5%，153/360）和最少（3.8%，9/240）的稳健特征。
本研究有助于更好地理解在用于MRgRT的三维T2W-TSE序列中，影像组学特征值对成像参数的定量依赖性。成像参数异质性应被视为影像组学变异性和不确定性的重要来源，为实现可靠的临床应用，必须对其进行良好协调。识别出的对成像参数稳健的特征有助于为可靠的影像组学建模进行影像组学特征的预筛选。
