Harwig S S, Harwig J F, Coleman R E, Welch M J
J Nucl Med. 1976 Jan;17(1):40-6.
We have investigated the in vivo behavior of 99mTc-fibrinogen, prepared by a mild and efficient electrolytic method employing tin electrodes. The clearance mechanisms of this agent were studied, and its efficacy for imaging deep-vein thrombi in dogs with an Anger camera was determined. The 99mTc-fibrinogen preparations, which are stable in vitro, undergo partial rapid exchange of the technetium with other plasma proteins and with anions of the blood buffer system in vivo, resulting in an early drop in the percent of radioactivity associated with clottable protein. However, very little or no oxidation to pertechnetate occurs. The nonclottable material is much more rapidly cleared from the blood than the remaining 99mTc-fibrinogen, and the proportion of clottable protein activity increases with time. The fraction of 99mTc-fibrinogen that remains intact in vivo is biologically active and will incorporate into thrombi. Higher thrombus-to-blood activity ratios are obtained with 99mTc-fibrinogen than with radioidinated fibrinogen when both agents are injected into dogs 4 hr after induction of femoral vein thrombosis. Clearly delineated images of the thrombi are obtained, beginning about 2.5 hr after injection. Thus, 99mTc-fibrinogen may be of clinical use as a thrombus-imaging agent in patients under-going active thrombosis, especially in regions of high blood pool.
我们研究了采用锡电极通过温和且高效的电解方法制备的99mTc-纤维蛋白原在体内的行为。研究了该试剂的清除机制，并确定了其使用安格相机对犬深静脉血栓成像的效果。99mTc-纤维蛋白原制剂在体外是稳定的，但在体内会与其他血浆蛋白以及血液缓冲系统的阴离子发生部分快速的锝交换，导致与可凝结蛋白相关的放射性百分比早期下降。然而，很少或几乎没有氧化为高锝酸盐的情况发生。不可凝结物质从血液中清除的速度比剩余的99mTc-纤维蛋白原快得多，并且可凝结蛋白活性的比例随时间增加。在体内保持完整的99mTc-纤维蛋白原部分具有生物活性，并会掺入血栓中。当在股静脉血栓形成4小时后将99mTc-纤维蛋白原和放射性碘化纤维蛋白原都注入犬体内时，99mTc-纤维蛋白原获得的血栓与血液活性比更高。在注射后约2.5小时开始获得清晰描绘的血栓图像。因此，99mTc-纤维蛋白原作为血栓成像剂可能对正在发生活动性血栓形成的患者具有临床应用价值，特别是在高血池区域。
