Study objectives: To determine whether sarcoidosis results in uptake on 99mTc-labeled depreotide (DP) scintigraphy and to generate preliminary data to guide the development of future trials exploring this imaging modality in sarcoidosis patients.
Design: Prospective cohort trial among a convenience sample of patients with sarcoidosis.
Setting: Tertiary care medical center pulmonary clinic.
Patients: Subjects in whom sarcoidosis has been diagnosed based on a biopsy revealing nonnecrotizing granulomas.
Interventions: Two hours after IV administration of 99mTc-DP, all patients underwent whole-body anterior and posterior planar imaging, followed by thoracic single-photon emission CT scanning. Images were interpreted by two nuclear medicine physicians who were blinded to the patient’s clinical status.
Measurements and results: The study cohort included 22 subjects (mean [± SD] age, 41.3 ± 9.3 years; 40% female). Approximately half of the cohort had stage I disease determined by chest radiographs (CXRs). The results of 99mTc-DP scintigraphy were positive for sarcoidosis in 18 individuals (81.8%; 95% confidence interval, 59.7 to 94.8%). Of the four persons lacking 99mTc-DP uptake, all had normalized their CXRs since the time of presentation. In the entire sample, the intraclass correlation between radiographic stage determined by CXR vs that determined by 99mTc-DP scintigraphy was robust (κ = 0.79; p = 0.0005). Among patients with positive 99mTc-DP scan findings, the correlation was stronger (κ = 0.94; p < 0.0001). Flow rates and lung volumes were lower in patients with parenchymal activity on 99mTc-DP scintigraphy (mean FEV1, 68.6 ± 13.9% predicted vs 84.5 ± 10.7% predicted, respectively [p = 0.012]; mean FVC, 74.0 ± 16.0% predicted vs 88.4 ± 12.7% predicted [p = 0.041]). 99mTc-DP scintigraphy correctly identified all sites of known nonpulmonary visceral involvement with sarcoidosis.
Conclusions: The results of 99mTc-DP imaging are often positive in sarcoidosis patients, and correlate with disease stage determined by CXR and pulmonary function. 99mTc-DP scintigraphy does not preclude the need for biopsy if this is indicated to confirm the diagnosis of sarcoidosis or to exclude the possibility of malignancy. 99mTc-DP scintigraphy merits further study in the evaluation and management of sarcoidosis.