Computer-based quantitative analysis of gallium-67 uptake in normal and diseased lungs

To study the 67Ga lung uptake as an index of inflammatory activity, we developed a computer-based method to process the data obtained from the 67Ga scan. Background radioactivity below the kidneys was subtracted from counts in all areas and given a score of 0; the maximal liver uptake was scored as 16. Radioactivity over six lung fields was scored by the computer between 0 and 16 and averaged to yield a mean 67Ga lung uptake index. This index of 67Ga lung accumulation correlates with histopathologic scores of inflammation in lung tissue and with bronchoalveolar lavage (BAL) levels of 67Ga radioactivity retrieval. This study reports the quantitative analysis of 67Ga lung uptake in normal subjects and patients with various pulmonary diseases. This method provides an objective index of inflammatory activity in lung tissues, and it is simple, sensitive, and discriminative.