Development of cost effective and reusable macro-aggregates of albumin for lung imaging

Objectives An attempt to develop cost effective and reusable macro aggregates of albumin (MAA) was made for the imaging of lungs.

Methods MAA were prepared and labeled with 99mTc by following the standard protocol which included incubation of formulation at 80 degrees for 10 minutes. The formulations were also incubated at 90 degrees. The rats were then injected intravenously with 99mTc MAA and were sacrificed after 10 minutes to study its distribution in the lungs and other non target tissues using gamma ray spectrometer. Standard protocol was further experimented upon for the optimization of particle size in order to achieve high target to non target ratio without using filters. Moreover, different formulations were prepared by incubating them at 80 degrees for different incubation times of 5, 10, 15, 20, 25 and 30 minutes.Formulations of MAA were also evaluated for their reuse abilities by reheating and re-labeling with 99mTc following storage at room temperatures which varied from 5 to 20 degrees, for different time durations 1, 2 and 9 days.

Results Formulation of MAA prepared by incubation at 80 degrees for 20 minutes showed highest target to non target ratio. Rats administered with the above said formulation were also sacrificed after two additional time intervals of 5 and 15 minutes. The target to non target ratio was maximum in animals sacrificed after 5 minutes of injecting them with MAA formulation prepared by heating at 80 degrees for 20 minutes.

Conclusions The formulation of MAA kept for 9 days showed the best target to non-target ratio after 5 minutes of intravenous injection to rats