Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48709, USA.
Ultrasound Med Biol. 2011 May;37(5):834-9. doi: 10.1016/j.ultrasmedbio.2011.01.012. Epub 2011 Mar 3.
Photoacoustic imaging is an emerging technique for anatomical and functional sub-surface imaging but previous studies have predominantly focused on time-domain analysis. In this study, frequency-domain analysis of the radio-frequency signals from photoacoustic imaging was performed to generate quantitative parameters for tissue characterization. To account for the response of the imaging system, the photoacoustic spectra were calibrated by dividing the photoacoustic spectra (radio-frequency ultrasound spectra resulting from laser excitation) from tissue by the photoacoustic spectrum of a point absorber excited under the same conditions. The resulting quasi-linear photoacoustic spectra were fit by linear regression and midband fit, slope and intercept were computed from the best-fit line. These photoacoustic spectral parameters were compared between the region-of-interests (ROIs) representing prostate adenocarcinoma tumors and adjacent normal flank tissue in a murine model. The mean midband fit and intercept in the ROIs showed significant differences between cancerous and noncancerous regions. These initial results suggest that such frequency-domain analysis can provide a quantitative method for tumor tissue characterization using photoacoustic imaging in vivo.
光声成像是一种新兴的用于亚表面解剖学和功能成像的技术，但以前的研究主要集中在时域分析上。在这项研究中，对光声成像的射频信号进行了频域分析，以生成用于组织特征描述的定量参数。为了考虑成像系统的响应，通过将组织的光声光谱（由激光激发产生的射频超声光谱）除以在相同条件下激发的点吸收体的光声光谱，对光声光谱进行了校准。通过线性回归和中频拟合对所得准线性光声光谱进行拟合，从最佳拟合线计算斜率和截距。在小鼠模型中，比较了代表前列腺腺癌肿瘤和相邻正常侧腹组织的感兴趣区域（ROI）之间的这些光声光谱参数。ROI 中的平均中频拟合和截距在癌症和非癌症区域之间存在显著差异。这些初步结果表明，这种频域分析可以为使用光声成像进行体内肿瘤组织特征描述提供一种定量方法。
