Standardized quantitative 67Ga scintigraphy in pulmonary sarcoidosis

A method of standardized quantitative 67Ga scintigraphy in the evaluation of pulmonary sarcoidosis is described. Standardization of 67Ga activity measurements was achieved by using an external attenuated 67Ga standard for comparison. The method was applied to control subjects (n = 24), and to patients (n = 88) suffering from biopsy-proven pulmonary sarcoidosis, whether or not treated with systemic or inhaled corticosteroids. The quantitative 67Ga activity values for pulmonary hili and parenchyma were found to be increased in patients, especially in those patients who were recently diagnosed and untreated. 67Ga accumulation in the liver showed normally a wide variation and appeared to be increased in patients with sarcoidosis, so that use of the liver radioactivity as the standard for comparison may lead to misinterpretation of the intrathoracic 67Ga activity distribution. Standardized quantitative 67Ga scintigraphy appeared to be a valuable tool in the management of pulmonary sarcoidosis and also opens up the possibility for results from different institutions to be compared. Supplementary digitized functional images improved the accuracy of the interpretation of routine analogue unprocessed images. Diffuse or local 67Ga accumulation in the chest was more readily discernible on digitized functional images than on analogue images.