Pulmonary uptake in 67-gallium citrate scintigraphy-the 'negative heart' sign.

Diffuse pulmonary uptake in 67-gallium citrate (67-Ga) scintigraphy occurs in a large number of neoplastic and inflammatory conditions. Discrimination between normal and abnormal 67-Ga uptake over the chest can be difficult and a simple visual method for identifying abnormal studies is described. A series of 39 gallium scintigrams was retrospectively reviewed by the authors and reported without knowledge of the patients' clinical condition. Subsequent clinical follow up was obtained to establish the accuracy of the scintigram interpretation. Comparison of pulmonary uptake with that over the cardiac area is recommended as a simple and reliable method of confirming that the level of pulmonary activity is abnormal. In highly abnormal cases the cardiac area is seen as a 'negative heart' image due to the considerably increased activity in the lungs. This sign is best seen with abnormal diffuse uptake but is also seen with abnormal focal uptake. Care must be taken, as the sign may be masked, if uptake over the cardiac area itself is increased.