High-Resolution Low-Field Molecular Magnetic Resonance Imaging of Hyperpolarized Liquids

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• 作者：Aaron M. Coffey ; Kirill V. Kovtunov ; Danila A. Barskiy ; Igor V. Koptyug ; Roman V. Shchepin ; Kevin W. Waddell ; Ping He ; Kirsten A. Groome ; Quinn A. Best ; Fan Shi ; Boyd M. Goodson ; Eduard Y. Chekmenev
• 刊名：Analytical Chemistry
• 出版年：2014
• 出版时间：September 16, 2014
• 年：2014
• 卷：86
• 期：18
• 页码：9042-9049
• 全文大小：508K
• ISSN：1520-6882

文摘

We demonstrate the feasibility of microscale molecular imaging using hyperpolarized proton and carbon-13 MRI contrast media and low-field (47.5 mT) preclinical scale (38 mm i.d.) 2D magnetic resonance imaging (MRI). Hyperpolarized proton images with 94 脳 94 渭m² spatial resolution and hyperpolarized carbon-13 images with 250 脳 250 渭m² in-plane spatial resolution were recorded in 4鈥? s (largely limited by the electronics response), surpassing the in-plane spatial resolution (i.e., pixel size) achievable with micro-positron emission tomography (PET). These hyperpolarized proton and ¹³C images were recorded using large imaging matrices of up to 256 脳 256 pixels and relatively large fields of view of up to 6.4 脳 6.4 cm². ¹³C images were recorded using hyperpolarized 1-¹³C-succinate-d₂ (30 mM in water, %P_13C = 25.8 卤 5.1% (when produced) and %P_13C = 14.2 卤 0.7% (when imaged), T₁ = 74 卤 3 s), and proton images were recorded using ¹H hyperpolarized pyridine (100 mM in methanol-d₄, %P_H = 0.1 卤 0.02% (when imaged), T₁ = 11 卤 0.1 s). Both contrast agents were hyperpolarized using parahydrogen (>90% para-fraction) in an automated 5.75 mT parahydrogen induced polarization (PHIP) hyperpolarizer. A magnetized path was demonstrated for successful transportation of a ¹³C hyperpolarized contrast agent (1-¹³C-succinate-d₂, sensitive to fast depolarization when at the Earth鈥檚 magnetic field) from the PHIP polarizer to the 47.5 mT low-field MRI. While future polarizing and low-field MRI hardware and imaging sequence developments can further improve the low-field detection sensitivity, the current results demonstrate that microscale molecular imaging in vivo is already feasible at low (<50 mT) fields and potentially at low (鈭? mM) metabolite concentrations.