Heo Hye-Young, Singh Munendra, Mahmud Sultan Z, Blair Lindsay, Kamson David Olayinka, Zhou Jinyuan
Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland, USA.
F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
Magn Reson Med. 2024 Dec;92(6):2641-2651. doi: 10.1002/mrm.30241. Epub 2024 Jul 31.
To evaluate the influence of the confounding factors, direct water saturation (DWS), and magnetization transfer contrast (MTC) effects on measured Z-spectra and amide proton transfer (APT) contrast in brain tumors.
High-grade glioma patients were scanned using an RF saturation-encoded 3D MR fingerprinting (MRF) sequence at 3 T. For MRF reconstruction, a recurrent neural network was designed to learn free water and semisolid macromolecule parameter mappings of the underlying multiple tissue properties from saturation-transfer MRF signals. The DWS spectra and MTC spectra were synthesized by solving Bloch-McConnell equations and evaluated in brain tumors.
The dominant contribution to the saturation effect at 3.5 ppm was from DWS and MTC effects, but 25%-33% of the saturated signal in the gadolinium-enhancing tumor (13%-20% for normal tissue) was due to the APT effect. The APT signal of the gadolinium-enhancing tumor was significantly higher than that of the normal-appearing white matter (10.1% vs. 8.3% at 1 μT and 11.2% vs. 7.8% at 1.5 μT).
The RF saturation-encoded MRF allowed us to separate contributions to the saturation signal at 3.5 ppm in the Z-spectrum. Although free water and semisolid MTC are the main contributors, significant APT contrast between tumor and normal tissues was observed.
评估混杂因素、直接水饱和（DWS）和磁化传递对比（MTC）效应对脑肿瘤中测量的Z谱和酰胺质子转移（APT）对比的影响。
使用3T的射频饱和编码3D磁共振指纹（MRF）序列对高级别胶质瘤患者进行扫描。对于MRF重建，设计了一个递归神经网络，以从饱和转移MRF信号中学习潜在多种组织特性的自由水和半固体大分子参数映射。通过求解Bloch-McConnell方程合成DWS谱和MTC谱，并在脑肿瘤中进行评估。
在3.5ppm处，对饱和效应的主要贡献来自DWS和MTC效应，但钆增强肿瘤中25%-33%的饱和信号（正常组织为13%-20%）归因于APT效应。钆增强肿瘤的APT信号明显高于正常白质（在1μT时为10.1%对8.3%，在1.5μT时为11.2%对7.8%）。
射频饱和编码的MRF使我们能够区分Z谱中3.5ppm处对饱和信号的贡献。虽然自由水和半固体MTC是主要贡献者，但在肿瘤组织和正常组织之间观察到了显著的APT对比。
