基于 Z 谱拟合的 APT 对比剂在低级别和高级别胶质瘤鉴别及肿瘤增殖检测中的应用
Improved Differentiation of Low-Grade and High-Grade Gliomas and Detection of Tumor Proliferation Using APT Contrast Fitted from Z-Spectrum.
机构信息
Department of Radiology, Tongji Hospital, Huazhong University of Science and Technology, 1095 Jiefang Ave., Wuhan, Hubei, 430030, China.
Center for Magnetic Resonance Research, University of Illinois at Chicago, 2242 West Harrison Street, Suite 103, Chicago, IL, 60612, USA.
出版信息
Mol Imaging Biol. 2018 Aug;20(4):623-631. doi: 10.1007/s11307-017-1154-y.
PURPOSE
The purpose of the study is to demonstrate the value of quantitative amide proton transfer (APT) imaging for differentiating glioma grades and detecting tumor proliferation.
PROCEDURES
This study included 32 subjects with 16 low-grade gliomas (LGG) and 16 high-grade gliomas (HGG) confirmed by histopathology. Chemical exchange saturation transfer (CEST) magnetic resonance imaging with APT weighting was performed on a 3 T scanner. After B correction, Z-spectra were fitted with Lorentzian functions corresponding to the upfield semi-solid magnetization transfer and nuclear overhauser enhancement (MT&NOE) effect, the direct saturation (DS) effect, and the downfield APT effect centered at around - 1.5, 0, and + 3.5 ppm, respectively. To compute the Z-spectral fitted APT (fitted_APT) in solid tumor tissue, double-peak histogram fitting of pixel MT&NOE effect from the whole tumor was used to remove necrosis regions. The fitted APT was then compared with the conventional APT based on magnetization transfer ratio asymmetry. Receiver operating characteristic (ROC) analysis was used to compare the performance between Z-spectral fitted contrasts and the con_APT for LGG versus HGG differentiation. Additionally, the correlations between the imaging contrasts (fitted_APT, con_APT, and fitted_MT&NOE) and Ki-67 labeling index for tumor proliferation were also evaluated.
RESULTS
Z-spectral fitted_APT shows improved statistical power for differentiating HGG and LGG (7.58 ± 0.99 vs. 6.79 ± 1.05 %, p < 0.05) than con_APT (4.34 ± 0.95 vs. 4.05 ± 2.02 %, p > 0.05) in solid tumor tissues. Analyses of whole tumor, on the other hand, have less differentiating power for both fitted_APT (p from 0.032 to 0.08) and con_APT (p from 0.696 to 0.809). Similarly, based on ROC analyses, fitted_APT shows larger area under the curve (AUC = 0.723) than con_APT (AUC = 0.543). The combination of fitted APT, DS, and MT&NOE further improved the specificity (75 %), diagnostic accuracy (78.2 %), and area under the curve (0.758) in differentiating LGG and HGG. Consistently, fitted_APT (r = 0.451, p = 0.018) is better correlated with Ki-67 than con_APT (r = 0.331, p = 0.092).
CONCLUSIONS
Fitted APT from Z-spectrum improves differentiation of low- and high-grade gliomas and better correlated with tumor proliferation than conventional APT.
目的
本研究旨在展示定量酰胺质子转移（APT）成像在区分胶质瘤级别和检测肿瘤增殖方面的价值。
方法
本研究纳入了 32 名经组织病理学证实的低级别胶质瘤（LGG）患者 16 名和高级别胶质瘤（HGG）患者 16 名。在 3T 扫描仪上进行化学交换饱和转移（CEST）磁共振成像与 APT 加权。在 B 校正后，采用洛伦兹函数拟合 Z 谱，分别对应于顺磁半固体磁化转移和核 Overhauser 增强（MT&NOE）效应、直接饱和（DS）效应以及位于约-1.5、0 和+3.5ppm 的 APT 效应。为了计算固体肿瘤组织中的 Z 谱拟合 APT（fitted_APT），使用整个肿瘤的像素 MT&NOE 效应的双峰直方图拟合来去除坏死区域。然后，将拟合的 APT 与基于磁化转移率不对称性的常规 APT 进行比较。接收器操作特征（ROC）分析用于比较 Z 谱拟合对比度与 con_APT 在 LGG 与 HGG 区分中的性能。此外，还评估了成像对比度（fitted_APT、con_APT 和 fitted_MT&NOE）与肿瘤增殖 Ki-67 标记指数之间的相关性。
结果
Z 谱拟合的 APT 显示出在区分 HGG 和 LGG 方面具有更好的统计能力（7.58±0.99%比 6.79±1.05%，p<0.05），优于 con_APT（4.34±0.95%比 4.05±2.02%，p>0.05）在固体肿瘤组织中。另一方面，对整个肿瘤的分析，fitted_APT（p 从 0.032 到 0.08）和 con_APT（p 从 0.696 到 0.809）的区分能力都较低。同样，基于 ROC 分析，拟合的 APT 显示出更大的曲线下面积（AUC=0.723）比 con_APT（AUC=0.543）。拟合 APT、DS 和 MT&NOE 的组合进一步提高了 LGG 和 HGG 之间的特异性（75%）、诊断准确性（78.2%）和曲线下面积（0.758）。一致地，fitted_APT（r=0.451，p=0.018）与 Ki-67 的相关性优于 con_APT（r=0.331，p=0.092）。
结论
Z 谱拟合的 APT 提高了低级别和高级别胶质瘤的区分能力，与肿瘤增殖的相关性优于常规 APT。
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