Improvements for clinical application of radioimmunoscintigraphy

放射性标记的肿瘤相关抗原单克隆抗体（MAb）显像是一种潜在的特异性定性诊断方法。用纯化的CEA免疫大肠癌细胞制备抗CEA单克隆抗体CEA 102，并应用于20例大肠癌患者。该方法有助于区分术后纤维化和局部复发。使用Fuji计算机射线照相术（FCR）进行另一项实验以研究放射性标记的CEA 102的特异性蓄积。FCR放射自显影显示，<131>在原发肿瘤和甚至小的肝转移瘤中，^I-CEA 102主要定位。虽然上述结果表明放射影像学对定性诊断是有用的，但其临床应用面临许多技术问题。在这项研究中，我们比较了F（ab '）2片段与整个IgG，并使用13 <111>In作为放射性示踪剂，发射CT作为额外的扫描仪。F（ab '）2从循环中排出的速度是全IgG的2倍，在注射后第1天图像清晰，而全IgG在注射后第3 ~ 4天图像清晰。·<111>In在肝脏中积累超过1周，但使用发射CT诊断直肠癌局部复发的合适工具。

Imaging using radiolabeled monoclonal antibody(MAb) to tumorassociated antigen is potentially specific approach to qualitative diagnosis. We Produced MAbCEA102 against CEA by immunization with purified CEA, and applied to 20 cases with colorectal cancer. This method was useful to distinguish postoperative fibrosis from local recurrence. Another experiment was performed to investigate the specific accumulation of radiolabeled CEA102 using Fuji Computed Radiography(FCR). Autoradiogram by FCR showed predominant localization of ^<131>I-CEA102 in primary tumor and even small liver metastases. Although the above results demonstrated that radioimaging was useful to qualitative diagnosis, many technical problems confront its clinical application. In this study, we compared F(ab')2 fragments with whole lgG, and used ^<111>In as a radiotracer, and Emission CT as an extra scanner. F(ab')2 were eliminated from the circulation twice as fast as whole IgG, and demonstrated clear image on the 1st day after injection, but 3rd to 4th day in whole IgG. ^<111>In was accumulated in liver more than 1 week, but suitable tools to diagnose local recurrence of rectal cancer using Emission CT.