Technetium-labeled depreotide (Tc-DP) is a novel radiopharmaceutical approved for use in the evaluation of solitary pulmonary nodules. Since Tc-DP binds to somatostatin receptors which are often present in inflammatory tissue, we hypothesized that Tc-DP nuclear scanning would be positive in patients with sarcoidosis.
We obtained Tc-DP scans in a convenience sample of patients with sarcoidosis. All patients had evidence of non-necrotizing granulomas and a clinical presentation consistent with sarcoidosis. Increased Tc-DP uptake in the thorax was the primary study endpoint. The site(s) of radiotracer activity (hila, lung parenchyma, or both) was also noted. Correlation between stage based on standard chest radiograph (CXR) and as determined by nuclear scan represented a secondary endpoint. All nuclear images were interpreted by nuclear medicine physicians blinded to the patient’s CXR and to clinical presentation. Results of spirometric testing were also compared between those with and without Tc-DP activity in the parenchyma.
The sample included 21 subjects (mean age 41.3±9.3 years, 52.4% male, 61.9% African American, 52.4% Stage I CXR). Seventeen patients (81.0%, 95% CI: 64.1%-94.6%) displayed thoracic activity with Tc-DP. Of the 4 persons lacking Tc-DP uptake, all had normalized their CXRs from presentation. In the entire sample, the intraclass correlation between stage determined by CXR vs. stage by Tc-DP was robust (κ=0.79, p=0.0005). Among patients with positive Tc-DP scans, the correlation was stronger (κ=0.94, p<0.0001). Flow rates and lung volumes were lower in patients with parenchymal activity (FEV1: 68.6±13.9% predicted vs. 84.5±10.7% predicted, p=0.0123; FVC 74.0±16.0% predicted vs. 88.4±12.7% predicted, p=0.0411).CONCLUSIONS: Tc-DP scans are often positive in patients with sarcoidosis. Tc-DP correlates well with CXR stage and pulmonary function.
Tc-DP may have a future role in the management of sarcoidosis. Clinical management trials incorporating Tc-DP are warranted.
A.F. Shorr, Berlex, Discussion of product research or unlabeled uses of Product.