经直肠的前列腺三维电阻抗断层成像的关键问题研究

The incidence of Prostate cancer is in the second place in men’s cancers all over the world. In China, the incidence of PCa is also rising in recent years. Transrectal ultrasound-guided biospy is the golden standard in the clinical, however, the method has the disadvantages of low sensitivity and high miss rate. Therefore, there is an urgent need to find a cheap and convenient method which can improve the detection rate and avoid excessive puncture for PCa early screening. Electrical impedance tomography is sensitive to the change information which occurs in incubation period and early phase of diseases, it is just EIT’s advantange to extract the electrical characteristics information at those times. In this project, in order to acquire the situation in prostate comprehensively and accurately, means of obtaining the conductivity distribution images in three dimension with high quality by the transrectal EIT probe is adopted. Simulation researches on modeling, exploration of the effect of different measurement factors acting on imaging, and the optimization of open-field reconstruction algorithm based on hare and soft prior knowledge to determine the boundary and solve the inverse problem of image reconstruction, are conducted. Accordingly, the completely open 3D-TREIT detection system including wireless EIT measurement probe and the host compute for prostate can be established as well.Then experiments will be employed for the subjects who have actual clinical significance to evaluate the sensitivity and specificity of the 3D-TREIT technique. The execution of this project will provide an implement method for PCa screening and early diagnosing and then accelerate the technique of PCa researches and applications in clinical.

前列腺癌(PCa)发病率居全球男性癌症第二位，且近年来在我国也呈升高趋势。目前临床的PCa筛查和确诊的金标准-经直肠超声(TRUS)引导下的穿刺活检，存在低灵敏度和高漏检率的问题。迫切需要一种检出率高、可避免过度穿刺、方便廉价的人群早期PCa筛查方法。电阻抗断层成像(EIT)对发生在疾病潜伏期或早期的变化信息十分敏感，提取疾病发生时的电特性信息是EIT的优势。项目拟经直肠置入EIT探头，给出高质量三维电导率分布图像结果，全面、准确了解前列腺内组织状况。将通过仿真建模，基于硬先验和软先验知识等共同确定场域边界求解开放场域图像重建问题，并经仿真探索影响3D-TREIT的测量因素，指导建立包括无线EIT测量探头和体外主机的完整开放式3D-TREIT检测系统。征集有实际临床意义的受试者(如确诊PCa患者)行3D-TREIT检测实验，评价检测效果，促进PCa临床应用检测技术与研究的进步。

低检出率、高费用、发现晚、过度穿刺是困扰临床PCa前列腺癌(Prostate cancer, PCa)诊疗的主要问题。经直肠电阻抗断层成像（transrectal electrical impedance tomography，TREIT）在PCa检测中有较大的应用价值和潜力。本项目通过建立与实际探头尺寸、前列腺大小及其位置关系接近的开放场域2D-TREIT和3D-TREIT前列腺成像模型，采用评价函数定量分析的方法基于模型确定了场域边界，对比了不同算法、不同电极系统、不同激励测量方式、不同的检测条件对成像的影响；基于仿真的结论构建了24电极探头和BME信号采集盒，进行阻抗前列腺信号采集；最终开展了3D-TREIT前列腺盐水槽实验验证。研究结果表明，不同成像算法3D-TREIT对前列腺成像的效果差异显著，Tikhonov-Noser组合正则化算法是本研究首选的算法；48电极系统成像质量高，但选择合理的激励-测量方式能高效利用24电极探头获取高质量图像; 采用所建场域模型，通过量化目标、探头和场域尺寸，可确定场域边界并实现2D-TREIT和3D-TREIT前列腺成像；盐水槽实验验证了本研究中研制的软件和硬件的有效性。进一步研究可围绕优化成像的算法、激励测量方式、优化硬件电路设计缩小探头的尺寸、开展更多的有意义的实验研究等方面进行。