Katharina Tkotz, Paula Zeiger, Jannis Hanspach, Claudius S Mathy, Frederik B Laun, Michael Uder, Armin M Nagel, Lena V Gast
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引用次数: 0
Abstract
Objective: To establish an image acquisition and post-processing workflow for the determination of the proton density fat fraction (PDFF) in calf muscle tissue at 7 T.
Materials and methods: Echo times (TEs) of the applied vendor-provided multi-echo gradient echo sequence were optimized based on simulations of the effective number of signal averages (NSA*). The resulting parameters were validated by measurements in phantom and in healthy calf muscle tissue (n = 12). Additionally, methods to reduce phase errors arising at 7 T were evaluated. Finally, PDFF values measured at 7 T in calf muscle tissue of healthy subjects (n = 9) and patients with fatty replacement of muscle tissue (n = 3) were compared to 3 T results.
Results: Simulations, phantom and in vivo measurements showed the importance of using optimized TEs for the fat-water separation at 7 T. Fat-water swaps could be mitigated using a phase demodulation with an additional B0 map, or by shifting the TEs to longer values. Muscular PDFF values measured at 7 T were comparable to measurements at 3 T in both healthy subjects and patients with increased fatty replacement.
Conclusion: PDFF determination in calf muscle tissue is feasible at 7 T using a chemical shift-based approach with optimized acquisition and post-processing parameters.
目的建立在 7 T 下测定小腿肌肉组织质子密度脂肪分数 (PDFF) 的图像采集和后处理工作流程:根据对有效信号平均值(NSA*)的模拟,优化了供应商提供的多回波梯度回波序列的回波时间(TE)。在模型和健康小腿肌肉组织(n = 12)中的测量结果验证了优化后的参数。此外,还评估了减少 7 T 时产生的相位误差的方法。最后,将在 7 T 下测量的健康受试者(9 人)和肌肉组织脂肪替代患者(3 人)小腿肌肉组织的 PDFF 值与 3 T 结果进行了比较:模拟、模型和体内测量结果表明,在 7 T 下使用优化的 TE 对于脂肪-水分离非常重要。在 7 T 下测量的肌肉 PDFF 值与在 3 T 下测量的值相当,无论是健康人还是脂肪替代增加的患者:结论:采用基于化学位移的方法,并优化采集和后处理参数,在 7 T 下测定小腿肌肉组织的 PDFF 是可行的。
期刊介绍:
MAGMA is a multidisciplinary international journal devoted to the publication of articles on all aspects of magnetic resonance techniques and their applications in medicine and biology. MAGMA currently publishes research papers, reviews, letters to the editor, and commentaries, six times a year. The subject areas covered by MAGMA include:
advances in materials, hardware and software in magnetic resonance technology,
new developments and results in research and practical applications of magnetic resonance imaging and spectroscopy related to biology and medicine,
study of animal models and intact cells using magnetic resonance,
reports of clinical trials on humans and clinical validation of magnetic resonance protocols.