Gurjar Nikita, Bailey Keith, El-Shenawee Magda
University of Arkansas, Department of Electrical Engineering and Computer Science, Fayetteville, Arkansas, United States.
Alnylam, Cambridge, Massachusetts, United States.
J Med Imaging (Bellingham). 2024 Nov;11(6):065503. doi: 10.1117/1.JMI.11.6.065503. Epub 2024 Dec 5.
We investigate terahertz (THz) polarimetry imaging of seven human breast cancer surgical specimens. The goal is to enhance image contrast between adjacent tissue types of cancer, healthy collagen, and fat in excised breast tumors. Based on the biological perception of random growth of cancer and invasion of surrounding healthy tissues in the breast, we hypothesize that cancerous cells interact with the THz electric field in a different manner compared with healthy cells. This difference can be best captured using multiple polarizations instead of single polarization.
Time domain pulsed signals are experimentally collected from each pixel of the specimen in horizontal-horizontal, vertical-horizontal, vertical-vertical, and horizontal-vertical polarizations. The time domain pulses are transformed to the frequency domain to obtain the power spectra and 16 Mueller matrix images. The whole-slide pathology imaging was used to interpret and label all images.
The results of the cross and co-polarization power spectrum images demonstrated a strong dependency on the tissue orientation with respect to the emitted and detected electric fields. At the 130-deg rotation angle of the scanned samples, the detector showed the strongest reflected signal in cross-polarization. Furthermore, the Mueller matrix images consistently demonstrated patterns in fresh and block tissues confirming the differentiation between tissue types in breast tumor specimens.
THz polarimetry imaging shows a potential for improving image contrast in excised tumor tissues compared with single polarization imaging. Cross-polarization signals demonstrated smaller amplitudes compared with co-polarized signals. However, averaging the signal during measurements has tremendously improved the image. Furthermore, in post-processing, averaging the frequency domain images and the Mueller matrix elements with respect to frequency has led to better image contrast. Some patterns in the Mueller matrix images were difficult to interpret leading to the necessity of more investigation of the Mueller matrix and its physiological interpretation of breast tumor tissues.
我们研究了七个人类乳腺癌手术标本的太赫兹（THz）偏振成像。目标是增强切除的乳腺肿瘤中癌组织、健康胶原蛋白和脂肪等相邻组织类型之间的图像对比度。基于对乳腺癌随机生长和周围健康组织浸润的生物学认识，我们假设癌细胞与太赫兹电场的相互作用方式与健康细胞不同。使用多个偏振而不是单个偏振可以最好地捕捉这种差异。
通过实验从标本的每个像素收集水平 - 水平、垂直 - 水平、垂直 - 垂直和水平 - 垂直偏振的时域脉冲信号。将时域脉冲转换到频域以获得功率谱和16个穆勒矩阵图像。使用全切片病理成像来解释和标记所有图像。
交叉偏振和共偏振功率谱图像的结果表明，相对于发射和检测电场，其对组织方向有很强的依赖性。在扫描样品130度的旋转角度下，探测器在交叉偏振中显示出最强的反射信号。此外，穆勒矩阵图像在新鲜组织和块状组织中一致地显示出模式，证实了乳腺肿瘤标本中组织类型的差异。
与单偏振成像相比，太赫兹偏振成像显示出改善切除肿瘤组织图像对比度的潜力。与共偏振信号相比，交叉偏振信号的幅度较小。然而，在测量过程中对信号进行平均极大地改善了图像。此外，在后期处理中，对频域图像和穆勒矩阵元素进行频率平均导致了更好的图像对比度。穆勒矩阵图像中的一些模式难以解释，这导致有必要对穆勒矩阵及其对乳腺肿瘤组织的生理学解释进行更多研究。
