Qu Min, Mehrmohammadi Mohammad, Truby Ryan, Graf Iulia, Homan Kimberly, Emelianov Stanislav
Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712.
Photoacoustics. 2014 Jun 1;2(2):55-62. doi: 10.1016/j.pacs.2013.12.003.
By mapping the distribution of targeted plasmonic nanoparticles (NPs), photoacoustic (PA) imaging offers the potential to detect the pathologies in the early stages. However, optical absorption of the endogenous chromophores in the background tissue significantly reduces the contrast resolution of photoacoustic imaging. Previously, we introduced MPA imaging - a synergistic combination of magneto-motive ultrasound (MMUS) and PA imaging, and demonstrated MPA contrast enhancement using cell culture studies. In the current study, contrast enhancement was investigated using the magneto-photo-acoustic (MPA) imaging augmented with dual-contrast nanoparticles. Liposomal nanoparticles (LNPs) possessing both optical absorption and magnetic properties were injected into a murine tumor model. First, photoacoustic signals were generated from both the endogenous absorbers in the tissue and the liposomal nanoparticles in the tumor. Then, given significant differences in magnetic properties of tissue and LNPs, the magnetic response of LNPs (i.e. MMUS signal) was utilized to suppress the unwanted PA signals from the background tissue and thus improves the PA imaging contrast. In this study, we demonstrated the 3D MPA image of LNP-labeled xenografted tumor in a live animal. Compared to conventional PA imaging, the MPA images show significantly enhanced contrast between the nanoparticle-labeled tumor and the background tissue. Our results suggest the feasibility of MPA for high contrast mapping of dual-contrast nanoparticles.
通过绘制靶向等离子体纳米颗粒（NPs）的分布，光声（PA）成像提供了在早期阶段检测病变的潜力。然而，背景组织中内源性发色团的光吸收显著降低了光声成像的对比度分辨率。此前，我们引入了MPA成像——磁动力超声（MMUS）和PA成像的协同组合，并通过细胞培养研究证明了MPA对比度增强。在当前研究中，使用添加了双对比度纳米颗粒的磁光声（MPA）成像研究对比度增强。将具有光吸收和磁性的脂质体纳米颗粒（LNPs）注入小鼠肿瘤模型。首先，从组织中的内源性吸收体和肿瘤中的脂质体纳米颗粒产生光声信号。然后，鉴于组织和LNPs在磁性上的显著差异，利用LNPs的磁响应（即MMUS信号）来抑制来自背景组织的不需要的PA信号，从而提高PA成像对比度。在本研究中，我们展示了在活体动物中LNP标记的异种移植肿瘤的3D MPA图像。与传统PA成像相比，MPA图像显示纳米颗粒标记的肿瘤与背景组织之间的对比度显著增强。我们的结果表明MPA用于双对比度纳米颗粒高对比度映射的可行性。
