Modified in vivo behaviour of 99mTc-labelled liver-spleen preparations due to 99Mo/99mTc-generator eluate impurities.

At irregular intervals, a 99mTc-labelled microcolloid for liver and spleen scintigraphy was reported to accumulate in the lungs, in the absence of any pathophysiological condition usually associated with this phenomenon. These findings were in direct contrast to the results obtained during quality control assays performed on the production batches of the kit. The authors tested the hypothesis that the presence of Al3+ ions in the generators eluate used to label the kit caused the formation of larger size aggregates. The experimental results suggest that the 99mTc-pertechnetate solution used for labelling contained far more than 40 micrograms Al3+ per ml, hence a many-fold increase of the maximum level tolerated by the pharmacopoeia. The authors advise caution when interpreting findings of pulmonary activity in the absence of clear evidence of pathological conditions that are sometimes associated with this biodistribution pattern.