Minimizing near-infrared autofluorescence in preclinical imaging with diet and wavelength selection.
Minimizing near-infrared autofluorescence in preclinical imaging with diet and wavelength selection.
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DOI：
10.1117/1.jbo.28.9.094805
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发表时间：
2023-09
影响因子：
3.5
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使用NIR-I(700至900 nm)照明和短波红外或NIR-II(1000至1700 nm)发射的临床前荧光成像可通过减少散射来增加组织穿透深度并提高分辨率。背景自体荧光可降低荧光成像中的信号背景比(SBR)；最大化SBR将进一步提高深部组织成像的效果。确定了啮齿动物的饮食、光照波长和发射范围对背景荧光和对比剂SBR的影响，以帮助将来的成像研究的实验设计。在670、760或808 nm照射后，使用IR活体临床前成像仪(Photon等)评估喂食或纯饲料喂养的小鼠的NIR-I()、NIR-II()和NIR-II Lp()区域的自体荧光。比较肝脏定位的吲哚青绿在不同成像条件下的SBR表明，肠道自发荧光是一个有问题的混杂因素。喂食食物的小鼠在胃肠道中显示出高水平的背景自发荧光，在较小程度上，当用670纳米的近红外成像光(700到975纳米)照射时，皮肤也表现出高水平的背景自发荧光，干扰了荧光标记组织的识别。背景自发荧光因下列任何变化而减少两个数量级以上：(1)纯净饮食；(2)760或808 nm光照的激发；或(3)NIR-II的发射(1000至1600或1250至1600 nm)。尽管SBR通常足以用于特征识别，但当以670 nm的激发和近红外I发射对喂食小鼠进行成像时，切换到纯饲料、使用更长的激发波长或使用更长的发射波长可以显著提高SBR。对成像条件和饮食的系统比较突出了故意选择实验参数(包括饮食、激发波长和发射波长范围)导致的自发荧光的减少和SBR的增加。
Preclinical fluorescence imaging with NIR-I (700 to 900 nm) illumination and short-wave infrared or NIR-II (1000 to 1700 nm) emission increases tissue penetration depth and improves resolution through decreased scattering. Background autofluorescence decreases signal-to-background ratios (SBR) in fluorescence imaging; maximizing SBR will further improve the impact of deep tissue imaging. The impact of rodent diet, illumination wavelength, and emission range on the background fluorescence and contrast agent SBR were determined to assist with the experimental design of future imaging studies. Following illumination with 670, 760, or 808 nm, autofluorescence in the NIR-I (), NIR-II (), and NIR-II LP () regions was assessed in mice fed chow or a purified diet using an IR VIVO preclinical imager (Photon, Etc.). Comparison of the SBR of liver-localized indocyanine green in the various imaging conditions indicated when gut autofluorescence was a problematic confounder. Mice fed chow exhibit high levels of background autofluorescence in the gastrointestinal tract and, to a lesser extent, skin when illuminated with 670 nm light for NIR-I imaging (700 to 975 nm), interfering with the identification of fluorescently labeled tissue. Background autofluorescence was reduced by more than two orders of magnitude by any of the following changes: (1) purified diet; (2) excitation with 760 or 808 nm illumination; or (3) emission in the NIR-II (1000 to 1600 or 1250 to 1600 nm). Although the SBR was generally sufficient for feature identification except when imaging of chow-fed mice with 670 nm excitation and NIR-I emission, switching to a purified diet, using longer excitation wavelengths, or using longer emission wavelengths improved SBR significantly. Systematic comparison of imaging conditions and diet highlights the reduction in autofluorescence and increase in SBR enabled by intentional choices in the experimental parameters including diet, excitation wavelength, and emission wavelength range.