Establishment of sentinel lymph node detection using impedance CT

对手术切除的器官进行电学评估，以确定正常组织和恶性病变之间是否存在电学差异。具体地说，评估了正常胃粘膜和恶性病变的介电特性，并计算了“tanδm”，即在δ分散范围内的最大tanβ。高分化腺癌癌变与正常胃粘膜的“tanδm”差异无统计学意义。而在低分化腺癌中，正常胃粘膜的“tanδm”为3.35±0.2 1，m-MP为4.6 6±0.79，SS-Se为7.6 0±1.2 3，差异有统计学意义。组织学显示，在结构变化方面，明显低分化或进展期肿瘤的“tanδm”较高。同时，通过改变胶体的直径、含量、剂量、给药时间和测量时间，尝试用铁胶体进行淋巴结聚集的电学检测，但正常淋巴结和含铁淋巴结的电学检测没有差异。此外，使用接触式多点测量电极和现有的阻抗分析仪(HP4194A)，在从1 kHz到1 MHz的多频率范围内测量了实验动物胃和大肠的介电特性。然而，数据的重复性很差，结果被认为反映了动物之间的个体差异。虽然基于等电势反投影获得的数据创建了介电性质的电导率分布图，但由于空间分辨率不足，无法在获得的图像上显示淋巴结。综上所述，虽然正常组织和癌组织之间存在电学差异，但在实践中利用阻抗CT建立前哨淋巴结检测可能会被证明是困难的。

Electrical evaluation of surgically resected organs was conducted to determine whether electrical differences exist between normal tissue and malignant lesions. Specifically, dielectric properties of normal gastric mucosa and malignant lesions were evaluated, and "tan δm", the maximum tan δ in the β dispersion range, was calculated. No significant differences were observed in "tan δm" between normal gastric mucosa and malignant lesions in patients with well-differentiated adenocarcinoma. However, in patients with poorly differentiated adenocarcinoma, "tan δm" was 3.35 ± 0.21 in normal gastric mucosa, 4.66 ± 0.79 in lesions with tumor depths of m to mp, and 7.60 ± 1.23 in areas with tumor depths of ss to se, indicating statistically significant differences. Histologically, "tan δm" was shown to be higher for markedly poorly differentiated or advanced tumors in terms of structural changes. Meanwhile, electrical detection of lymph node accumulation using iron colloids was attempted by altering colloid diameter, content, dose, administration time, and measurement time, but no electrical differences were observed between normal lymph nodes and lymph nodes containing iron. In addition, the dielectric properties of experimental animal stomachs and large intestines were measured in a multi-frequency range from 1 kHz to 1 MHz using electrodes for contact-type multiple-point measurements and an existing impedance analyzer (HP4194A). However, data reproducibility was poor, and the results were thought to reflect individual differences among animals. Although a conductivity distribution map of dielectric properties was created based on obtained data using equipotential back-projection, lymph nodes could not be visualized on obtained images due to insufficient spatial resolution. Based on the above, although electrical differences may exist between normal and cancer tissues, establishment of sentinel lymph node detection using impedance CT in practice may prove difficult.