Effect of reference spectra in spectral fitting to discriminate enzyme-activatable photoacoustic probe from intrinsic optical absorbers
Effect of reference spectra in spectral fitting to discriminate enzyme-activatable photoacoustic probe from intrinsic optical absorbers
复制标题
光谱拟合中参考光谱对区分酶激活光声探针与固有光吸收体的影响
DOI：
10.1117/12.2213778
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
M Ishihara
中科院分区：
文献类型：
--
作者：
T Hirasawa;S Okawa;RJ Iwatate;M Kamiya;Y Urano;M Ishihara
多光谱光声（MS-PA）成像技术已被研究用于分子探针在强背景信号下的成像。光谱拟合方法（SFM）通过将从MS-PA图像计算的PA光谱分别拟合到探针和背景的参考光谱来区分探针信号和背景信号。由于血红蛋白是可见光至近红外波长范围内的主要光吸收体，因此血红蛋白的吸收光谱已被广泛用作参考背景光谱。然而，从异质生物组织产生的背景信号的光谱不同于参考背景光谱，这是由于存在其它固有光吸收体和光散射效应。由于这种差异，背景信号部分地保留在探针图像中。为了使注射到小鼠皮下肿瘤中的探针清晰成像，我们将黑素体吸收光谱添加到参考背景光谱中，因为皮肤含有不可忽略的浓度的黑素体，并且光谱与生物组织的散射光谱非常相似。注射到小鼠皮下肿瘤中的探针是一种酶可激活的探针，其仅在γ-谷氨酰转肽酶（一种与癌症相关的酶）存在下显示其原始颜色。该探针已成功用于癌症的快速荧光成像。作为MS-PA成像的结果，通过考虑黑素体吸收光谱，成功地抑制了背景信号，从而获得更清晰的探针图像。我们的MS-PA成像方法提供了成功的肿瘤成像小鼠注射可激活的PA探针。
Multispectral photoacoustic (MS-PA) imaging has been researched to image molecular probes in the presence of strong background signals produced from intrinsic optical absorbers. Spectral fitting method (SFM) discriminates probe signals from background signals by fitting the PA spectra that are calculated from MS-PA images to reference spectra of the probe and background, respectively. Because hemoglobin is a dominant optical absorber in visible to near-infrared wavelength range, absorption spectra of hemoglobin have been widely used as reference background spectra. However, the spectra of background signals produced from heterogeneous biological tissue differ from the reference background spectra due to presence of other intrinsic optical absorbers and effect of optical scattering. Due to the difference, the background signals partly remain in the probe images. To image the probe injected in subcutaneous tumors of mice clearly, we added the melanosome absorption spectrum to the reference background spectra because skin contains nonnegligible concentration of melanosome and the spectrum is very similar to the scattering spectrum of biological tissue. The probe injected in the subcutaneous tumor of mice was an enzyme-activatable probe which show their original colors only in the presence of γ-glutamyltranspeptidase, an enzyme associated with cancer. The probes have been successfully used for rapid fluorescence imaging of cancer. As a result of MS-PA imaging, by considering the melanosome absorption spectrum, the background signals were successfully suppressed and then clearer probe image was obtained. Our MS-PA imaging method afforded successful imaging of tumors in mice injected with activatable PA probes.