Distribution of 99mTc colloid in the thoracic cavity of patients with malignant pleural effusions

The distribution of labelled tetracycline in the pleural space of patients with malignant effusions has been shown not to improve significantly after rotating the patient. As the number of patients was small, we investigated the distribution of an inert radio labelled colloid (99mTc) in the pleural space directly after administration and after 1 h of rotation. Nineteen examinations were performed in 18 patients with malignant pleural effusions. In two out of 19 examinations (11%) a considerable improvement in distribution was observed and some improvement was found in five out of 19 examinations (26%). The relation between distribution and the effect of tetracycline pleurodesis at 12 weeks and the identification of patients for whom pleurodesis would not be successful were also studied. The analysis of the distribution and outcome of pleurodesis was hampered by the fact that additional anti tumour treatments were given after pleurodesis.

The influence of rotation on the distribution of 99mTc-colloid in the pleural space is minimal and indicates that this could be omitted. A distribution pattern predictive of failure of pleurodesis could not be identified in this study.