Lymphoscintigraphy findings in patients with chylothorax: influence of biochemical parameters

Abstract

Background Chylothorax is a condition that can be challenging to diagnose due to its nonspecific clinical presentation. Several biochemical parameters of chylous pleural effusion have been identified as important indicators for the diagnosis of chylothorax. Lymphoscintigraphy, a non-invasive imaging technique, is also used to evaluate chylothorax and determine the location of chyle leakage. This study aimed to evaluate the correlation between the biochemical parameters of chylous pleural effusion and 99mTc-dextran (DX) lymphoscintigraphy in diagnosing chylothorax. Material and methods A total of 120 patients were enrolled, 83 of the patients had unilateral chylothorax, and 37 had bilateral chylothorax. All patients conducted both 99mTc-DX lymphoscintigraphy and pleural effusion laboratory analysis. The images were classified into positive and negative groups based on whether an abnormal accumulation of the radioactive tracer was observed in the thorax on 99mTc-DX lymphoscintigraphy. And the biochemical parameters of the two groups were compared. Results Among these patients, 101 (84.17%) had exudative effusions, and 19 (15.83%) had transudative effusions, according to the levels of pleural effusion protein, lactate dehydrogenase and cholesterol. Abnormal tracer accumulation in thorax was observed in 83 patients (69.17%). Exudative and transudative chylothorax are not associated with lymphoscintigraphy results (P = 0.597). In all biochemical parameters, lymphoscintigraphy positive group had significantly higher levels of pleural effusion triglyceride and pleural effusion triglyceride/serum triglyceride ratio compared with negative group (P = 0.000 and P = 0.005). The cutoff values that we identified for pleural effusion triglycerides and pleural effusion triglyceride/serum triglyceride ratio were 2.870 mmol/L and 4.625, respectively, which can facilitate differentiating the positive and negative results on lymphoscintigraphy. Conclusion Lymphoscintigraphy technique is a reliable diagnostic tool for the qualitative evaluation of chylous pleural effusion. Higher pleural effusion triglyceride level and pleural effusion triglyceride/serum triglyceride ratio indicate a positive result in patients with chylothorax on lymphoscintigraphy, and the cutoff values of 2.870 mmol/L and 4.625 can help with the diagnosis.