Optimal conditions of ^99mTc eluate for the radiolabeling of ^99mTc-sestamibi

Our nuclear pharmacy has reported that a failed radiochemical purity (RCP) (i.e., RCP <90%) of ^99mTc sestamibi may be associated with the use of a first elution at later stages from a long-ingrowth time (i.e., ≤72 h) wet-column generator. The primary purpose of this study was to evaluate the effects of ^99mTc eluates from wet and dry column generators on the RCP of ^99mTc-sestamibi under the above conditions. RCP values were found to be measurably higher and kit failure rates lower with the use of dry-column generator eluate. Using a dry-column generator eluate, Cardiolite® kits were prepared with 11.10 GBq of ^99mTc at 3, 4, and 5 h postelution and 5.55 GBq at 6, 10, 11, and 12 h postelution. Our data suggest that when 11.10 GBq of ^99mTc from a dry column generator with ≤72-h ingrowth was used to prepare ^99mTc sestamibi, kit failure started to occur using ^99mTc eluate at approximately 4 h postelution. When 5.55 GBq was used to reconstitute the kit, RCP failure began to occur using ^99mTc eluate ~10 h postelution and was likely to occur by 12 h postelution. Dry column generator eluates have lower kit failures than do wet column generators; the failure rate can be reduced even further by avoiding the addition of high activities of ^99mTc and long elution times.