All patients also underwent a CXR prior to 99mTc-DP scanning. The PFT results and Dlco values were interpreted in accordance with the guidelines of the American Thoracic Society. Normal values were derived from Crapo et al, and corrections for race were made. The Dlco was further corrected for hemoglobin. Values for PFTs and Dlco were considered to be abnormal if they fell outside the 95% confidence interval (CI) for the predicted values. We measured the erythrocyte sedimentation rate and the angiotensin-converting enzyme (ACE) level. We recorded current and prior therapy for sarcoidosis and the presence of extrapulmonary sarcoidosis. Extrapulmonary sarcoidosis was defined based on the classifications used by A Case Control Epidemiology Study of Sarcoidosis study group.
For 99mTc-DP scintigraphy, we utilized a commercially available radiolabeled pharmaceutical (NeoTect; Berlex; Raritan, NJ). This comes in kit form with vials of 50 |j,g DP peptide. The DP is reconstituted with approximately 50 mCi 99mTc pertechnetate. Within 3 h of kit preparation, the 99mTc-DP was injected IV into each patient. Approximately 1 h after injection, image acquisition was begun. Anterior and posterior planar whole-body images were obtained with a scan speed of 15 cm/min in a matrix of 128 X 128. Immediately after whole-body planar imaging, thoracic single-photon emission CT imaging was performed. Singlephoton emission CT imaging employed a 64 X 64 matrix.
The primary study end point was the occurrence of a positive finding of the 99mTc-DP scan. Two nuclear medicine physicians interpreted all 99mTc-DP scans. These observers were blinded to the patient’s clinical status and the results of other testing. Disagreements as to interpretation were resolved through consensus. The relationship between the stage determined by CXR and the stage determined by 99mTc-DP scanning represented a secondary end point. Hence, the interpreters categorized the findings of the 99mTc-DP images as negative, positive in the hila alone, positive in the hila and the parenchyma, or positive only in the lung parenchyma, corresponding to the CXR staging system developed by Scadding. In instances in which the CXR had changed (eg, the disease had resolved) in the interval between diagnosis and the time when nuclear imaging was performed, we compared both CXRs to the 99m Tc-DP scan. We also compared the 99mTc-DP interpretations with the results of PFTs. The activity in extrapulmonary locations seen on 99mTc-DP scans was recorded in order to identify sites of nonpulmonary sarcoidosis.