Lung-uptake and -washout of MIBG in sarcoidosis

SummaryBackgroundThe aim of this study was to evaluate the uptake and -washout of I-123 meta-iodobenzylguanidine (MIBG), reflecting norepinephrine metabolism, in the lungs in patients with sarcoidosis.MethodsLung I-123 MIBG kinetics was assessed in 43 patients with sarcoidosis. The range of disease duration was 1–16 years (median: 3 years). Thirteen patients had radiographic stage 0–I, 30 patients had radiographic stage II–IV. Serological clinical parameters and small fibre neuropathy, as assessed by temperature threshold testing (TTT) were measured in 39/43 patients. 31/39 patients had an abnormal TTT. Eleven healthy controls participated in this study. Both dual head planar and dual headed SPECT images of the thoracic regions were made. The uptake of I-123 MIBG and the washout percentage were calculated in sarcoidosis patients and compared with the healthy persons.ResultsLung I-123 MIBG uptake in patients with sarcoidosis did not differ from controls. The lung washout of I-123 MIBG was significantly (p⩽0.01) decreased in sarcoidosis. Remarkably this was most clearly seen in patients with an abnormal TTT and in patients with more advanced radiographic pulmonary involvement (radiographic stages II–IV) but not in patients with decreased lung function (FVC<80% or DLCO<80%).ConclusionThe inflammatory process of the lungs in sarcoidosis seems not to affect pulmonary vasculature. In sarcoidosis decreased lung washout of I-123 MIBG might, at least partly, be explained by sympathetic autonomic nerve dysfunction. Future studies are needed to explore the clinical relevance of this observation.