Chromatographic Quality of Three 99mTc Bone-Imaging Agents

Increased uptake by stomach, thyroid, and liver incidental to bone scanning suggests that 99 mTc-pertechnetate (99 mTc0r) and reduced hydrolyzed technetiumtin colloid [99 mTc(OH)4 · Sn (OH)z] are radiochemical impurities present in Sn-diphosphonate (EHDP) and Sopyrophosphate (PP). The amount of uptake in stomach, salivary glands, and thyroid is due to the presence of pertechnetate and is related to the time interval between preparation and administration. An evaluation of the bone agents 99 mTc-EHDP and 99 mTc-PP showed increasing amounts of 99mTcOr during a 5-h interval, while 99 mTc-EHDP with stabilizer was unchanged. In contrast, the colloid concentration was the same in all agents tested and did not change with time. Administration of 99 mTc-EHDP or 99 mTc-PP within 2 h after preparation will reduce the amount of free pertechnetate and improve bone-imaging quality. Our data suggest that a stabilizer should be used when the interval from preparation to administration is expected to exceed 2h.