Normal appearance and reproducibility of liver-spleen studies with /sup 99m/Tc sulfur colloid and /sup 99m/Tc microalbumin colloid

In order to determine the normal biodistribution and reproducibility of /sup 99m/Tc sulfur colloid and /sup 99m/Tc microalbumin colloid, each of ten normal subjects was studied twice with each of the two agents. In overexposed delayed analog images of the anterior chest, some thyroid radioactivity was demonstrated in all of 20 microalbumin colloid studies and in none of 20 sulfur colloid studies; lung radioactivity was seen in 19 of 20 (95%) sulfur colloid studies and in none of the microalbumin colloid studies (both p less than 0.001). Delayed digital images showed that the sulfur colloid gave a higher lung-to-heart ratio, a higher lung-to-liver ratio, and a lower bone marrow-to-liver ratio compared with microalbumin colloid (all p less than 0.05). In general, reproducibility was poor for both agents. We conclude that while there are some differences between these two radiocolloids, the differences do not indicate a superiority of the newer Tc-99m microalbumin colloid over the established Tc-99m sulfur colloid for liver-spleen imaging