INVESTIGATION OF MEASURES TO REDUCE INTERFERING ABDOMINAL ACTIVITY ONREST MYOCARDIAL IMAGES WITH TC-99M SESTAMIBI

With the new myocardial agent Tc-99m sestamibi, relatively high abdomi nal uptake represents a major limiting factor. The effect of a standar d feeding (commercial milkshake taken immediately after injection), an d posture (standing versus sifting for 10 minutes postinjection) on th e resting biodistribution of sestamibi was investigated in patients re ceiving 3 to 5 MBq/kg injections as part of rest-stress tomography. An cillary anterior 1-minute images of heart and abdomen were obtained at 15 minutes postinjection and 90 to 140 minutes postinjection in 32 pa tients, randomized to feeding and postural treatments. Feeding decreas ed the activity in the gallbladder at both 15 and 110 minutes, but had no effect on liver parenchyma; activity in a background rectangle imm ediately beneath the heart was decreased by feeding only on the 15-min ute images. An effect of posture was not apparent. Further study of th e acute effects of a milkshake in eight patients showed a prompt reduc tion of 26% in a subdiaphragmatic background rectangle, but a more gra dual decline in gallbladder counts. Thus, feeding of lipid after injec tion is not an essential component of sestamibi imaging protocols; ora l administration of fluid immediately before imaging may help reduce i nterfering gastric activity.