Department of Physics & Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, US.
Biomedical Research Imaging Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Chemphyschem. 2022 Dec 16;23(24):e202200438. doi: 10.1002/cphc.202200438. Epub 2022 Sep 29.
Detection of bare gas microbubbles by magnetic resonance (MR) at low concentrations typically used in clinical contrast-ultrasound studies was recently demonstrated using hyperCEST. Despite the enhanced sensitivity achieved with hyperCEST, in vivo translation is challenging as on-resonance saturation of the gas-phase core of microbubbles consequently results in saturation of the gas-phase hyperpolarized Xe within the lungs. Alternatively, microbubbles can be condensed into the liquid phase to form perfluorocarbon nanodroplets, where Xe resonates at a chemical shift that is separated from the gas-phase signal in the lungs. For ultrasound applications, nanodroplets can be acoustically reverted back into their microbubble form to act as a phase-change contrast agent. Here, we show that low-boiling point perfluorocarbons, both in their liquid and gas form, generate phase-dependent hyperCEST contrast. Magnetic resonance detection of ultrasound-mediated phase transition demonstrates that these perfluorocarbons could be used as a dual-phase dual-modality MR/US contrast agent.
近期的一项研究应用高浓度交换饱和转移（hyperCEST）技术，探测到了临床常用的低浓度微气泡中的裸气体。尽管高浓度交换饱和转移技术提高了灵敏度，但由于微气泡气相核的共振饱和，导致肺部中气相的 hyperpolarized Xe 饱和，这对体内转化仍然具有挑战性。另一种方法是将微气泡冷凝成液相，形成全氟碳纳米液滴，其中 Xe 的共振频率与肺部中的气相信号分离。对于超声应用，纳米液滴可以通过声学反转回微气泡形式，作为相变化对比剂。在这里，我们表明，无论是液态还是气态的低沸点全氟碳化合物都会产生与相相关的 hyperCEST 对比。超声介导的相变的磁共振检测表明，这些全氟碳化合物可用作双相双模态磁共振/超声对比剂。
