Sentinel lymph node mapping using 99m Tc-labeled mannosyl-neoglycoalbumin and small semiconductor gamma camera for gastrointestinal cancers.

甘露糖基-新糖蛋白（NMA）是一种小颗粒，能够与网状内皮细胞上的甘露糖受体结合。因此，如果将其用作前哨淋巴结（SLN）标测的示踪剂，预计其将显示从其注射部位的快速清除和在区域淋巴结（LN）内的高保留。半导体γ照相机（SGC）体积小，可以在手术室中使用，并且与常规闪烁照相机相比具有更高的空间分辨率特异性。本文提出了一种新的胃肠道肿瘤前哨淋巴结定位技术--99 mTc标记的NMA和SGC联合应用，并在猪模型上进行了验证。在器官的局部淋巴结区域内描绘了3个淋巴结的平均数量，甚至是邻近注射部位的淋巴结。与我国胃肠道肿瘤SLN定位常用的99 m标记锡胶体相比，示踪剂从注射部位的清除快2倍，在淋巴结中的保留高4倍，这表明新示踪剂可以避免所谓的“透照现象”。SGC还通过配备光学相机和输出真实的图像的能力进行了改进。将真实的图像与放射性图像进行时间融合，以便于精确定位放射性结节。胃癌手术标本的SGC结果表明，该方法能准确定位肿瘤注射部位，具有良好的临床应用价值。

Mannnosyl-neoglycoalbumin (NMA) is a small sized particle which has a capability to bind to mannose receptors on reticuloendotherial cells. Thus, it is expected to show rapid clearance from its injection sites and high retention within regional lymph nodes (LNs) if it is used as a tracer for sentinel lymph node (SLN) mapping. Semiconductor gamma camera (SGC) is small enough to use in an operating room and has higher spatial resolution specificity compared with conventional scintillation camera. A new technique to map SLNs for gastrointestinal cancers using a combination of 99mTc-labeled NMA and SGC was proposed and its usefulness was tested in a swine model.99mTc-labeled NMA was administered to both stomach and rectum of three specific pathogen free swines of three-month-old. Mean number of 3 LNs, even nodes adjacent to the injection site, were depicted within the regional LNs area of the organ. Clearance of the tracer from injection sites was two times faster, and retention in the LNs was four times higher as compared to 99m-labeled tin colloid, that were commonly used for SLN mapping of gastrointestinal cancers in our country, indicating an usefulness of the new tracer to avoid so-called "shine-through phenomenon".SGC was also refined with furnishing an optical camera and a capability to out put real-time fusion images of real and radioactive view, in order to facilitate to pinpoint radioactive nodes. SGC of this new version was also tested on surgical specimen of gastric cancer, and injection sites were precisely localized on the synthesized images, thus, indicating that this new SLN mapping technique is useful and ready for clinical use.