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首页> 外文期刊>Medical Imaging, IEEE Transactions on >Generating Super Stimulated-Echoes in MRI and Their Application to Hyperpolarized C-13 Diffusion Metabolic Imaging
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Generating Super Stimulated-Echoes in MRI and Their Application to Hyperpolarized C-13 Diffusion Metabolic Imaging

机译：MRI中超刺激回波的产生及其在超极化C-13扩散代谢成像中的应用

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Stimulated-echoes in MR can be used to provide high sensitivity to motion and flow, creating diffusion and perfusion weighting as well as $T_{1}$ contrast, but conventional approaches inherently suffer from a 50% signal loss. The super stimulated-echo, which uses a specialized radio-frequency (RF) pulse train, has been proposed in order to improve the signal while preserving motion and $T_{1}$ sensitivity. This paper presents a novel and straightforward method for designing the super stimulated-echo pulse train using inversion pulse design techniques. This method can also create adiabatic designs with an improved response to RF transmit field variations. The scheme was validated in phantom experiments and shown in vivo to improve signal-to-noise ratio (SNR). We have applied a super stimulated-echo to metabolic MRI with hyperpolarized $^{13}{rm C}$-labeled molecules. For spectroscopic imaging of hyperpolarized agents, several repetition times are required but only a single stimulated-echo encoding is feasible, which can lead to unwanted motion blurring. To address this, a super stimulated-echo preparation scheme was used in which the diffusion weighting is terminated prior to the acquisition, and we observed a SNR increases of 60% in phantoms and 49% in vivo over a conventional stimulated-echo. Experiments following injection of hyperpolarized $[1{hbox{-}}^{13}{rm C}]$ -pyruvate in murine transgenic cancer models have shown improved delineation for tumors since signals from metabolites within tumor tissues are retained while those from the vasculature are suppressed by the diffusion preparation scheme.
机译：MR中的受激回波可用于提供对运动和流的高灵敏度，从而产生扩散和灌注权重以及$ T_ {1} $对比度，但是传统方法固有地遭受了50％的信号损失。已经提出了使用专用射频（RF）脉冲序列的超级受激回波，以便在保持运动和$ T_ {1} $灵敏度的同时改善信号。本文提出了一种使用反转脉冲设计技术设计超级受激回波脉冲序列的新颖直接的方法。该方法还可以创建对射频发射场变化具有改善响应的绝热设计。该方案已在幻像实验中得到验证，并在体内显示出可提高信噪比（SNR）。我们将超刺激回波应用于带有超极化$ ^ {13} {rm C} $标记分子的代谢MRI。对于超极化剂的光谱成像，需要几个重复时间，但是仅单个受激回波编码是可行的，这会导致不必要的运动模糊。为了解决这个问题，使用了超级刺激回声制备方案，其中扩散权重在采集之前终止，并且我们观察到，与传统的刺激回声相比，幻像的SNR增加了60％，体内的SNR增加了49％。在鼠类转基因癌症模型中注射超极化的$ [1 {hbox {-}} ^ {13} {rm C}] $-丙酮酸后的实验显示，由于保留了肿瘤组织内代谢物的信号，而保留了来自肿瘤组织内的代谢物的信号，因此改善了对肿瘤的描述。通过扩散制备方案抑制脉管系统。

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