Is there any relation between residual volume (RV) and tomographic pattern in Sarcoidosis patients at diagnosis?

<bold>Background:</bold> Pulmonary Sarcoidosis (PS) presents a wide range of radiological abnormalities. Authors observed that decreased RV could be the only alteration in pulmonary function tests (PFTs) in PS and tried to relate to the CT pattern. <bold>Objectives:</bold> Investigating the relation between decreased RV and CT pattern at PS diagnosis. <bold>Methods:</bold> Retrospective, observational, longitudinal study collecting data of 113 patients from University Hospital of Bellvitge at PS diagnosis. <bold>Results:</bold> Mean age of 48.7 +/- 12.6 years. 56.6% female, 19.5% active smokers and 31% ex-smokers. HRCT patterns observed: nodular (50.4%), ground-glass (11.5%), fibrosis (8%), reticular (3.5%), consolidation (0.9%) and only adenopathies (classified as normal: 25.7%). The relation between RV and CT pattern and predominance localization (peripheric, central, diffuse or normal) was analyzed by Wilcoxon rank sum test. RV increased/decreased according to the pattern and predominance localization (p<0.001). RV increased (>120% of ref) in nodular pattern with central predominance (median 134.5% [Q1 117.3; Q3 144.5]) and in normal pattern (median 112% [Q1 89.9; Q3 140.7]). RV decreased (<90% of ref.) in fibrotic pattern (median 71.2% [Q1 64.8; Q3 97.3]) and nodular pattern with peripheric predominance (median 84% [Q1 75.7; Q3 96.2]). There was no relation between RV and tobacco, FEV1 or MEF50%-25%. <bold>Conclusion:</bold> RV in PFT seem to predict the type and distribution of HRCT pattern in PS. These results support the importance to consider RV and request a HRCT scan when respiratory symptoms are concomitantly found with altered RV. The integration of functional and radiological data could improve the early diagnosis of PS.