@article {SalitoP656, author = {Caterina Salito and Livia Barazzetti and Jason C. Woods and Andrea Aliverti}, title = {Regional differences in specific gas volume in the healthy lung}, volume = {40}, number = {Suppl 56}, elocation-id = {P656}, year = {2012}, publisher = {European Respiratory Society}, abstract = {Specific gas volume (SVg) converts CT lung density into the physiological meaningful index of volume of gas per gram of tissue (Salito, C. et al. Radiology 2009; 253:380-389). The aim of this study was to establish a baseline of SVg values for healthy lungs, to study regional differences of SVg in the different lung segments and to evaluate the influence of the reconstruction kernel on SVg parameters.CT scans of 10 healthy volunteers were performed during breath holding at total lung capacity (TLC) and residual volume (RV). CT images were reconstructed using Siemens b30f and b50f convolution kernels. For each broncho-pulmonary segment, one cylindrical region of interest within the parenchyma was selected.Mean SVg was significantly higher with b50f both at TLC and RV (12.1 vs 7.5 ml/g, p\<0.001) while median SVg was not affected by the reconstruction filter (7.8 vs \~{}2.9 ml/g for TLC and RV, respectively). ΔSVg =SVg,TLC - SVg,RV was independent of broncho-pulmonary segment.Variability of ΔSVg/ΔV values between different broncho-pulmonary segments within the same subject and between different subjects within the same broncho-pulmonary segment was very low. Higher values of SVg were found in more anterior locations with little to no cranio-caudal or lateral dependence.In conclusion, in healthy subjects SVg and ΔSVg are highly homogeneous within the lung. Conversely, in emphysema the expected larger heterogeneity can potentially be used as a measure of inhomogeneous lung emptying and a biomarker for surgical planning and post-treatment evaluation.This work was supported by a NIH grant R01- HL090806.}, issn = {0903-1936}, URL = {https://erj.ersjournals.com/content/40/Suppl_56/P656}, eprint = {https://erj.ersjournals.com/content/40/Suppl_56/P656.full.pdf}, journal = {European Respiratory Journal} }