The low attenuation area on dual-energy perfusion CT: Correlation with the pulmonary function tests and quantitative CT measurements

Abstract Purpose To retrospectively investigate the distribution of the low attenuation area (LAA) on dual energy perfusion CT (DEpCT) in comparison with the results of pulmonary function tests (PFTs) and quantitative CT measurements. Materials and methods Twenty-eight patients (15 male and 13 female; mean age: 62.21 years) underwent DEpCT and PFTs within a 1-month interval. The ranges of the LAA on DEpCT were classified into six groups with attenuation values of 0–3, 0–5, 0–8, 0–10, 0–13 and 0–15 HU and the ratios of LAA in each group were compared with the percentage of forced expiratory volume in the 1st second (%FEV1.0 ), FEV1.0 /forced vital capacity (FEV1.0 /FVC) and the relative area of the lung with attenuation coefficients lower than −950 HU (RA−950 ). Results The LAAs on the DEpCT images were significantly correlated with the RA−950 , %FEV1.0 and FEV1.0 /FVC, and the regression analysis showed that the best values of LAA on DEpCT were 0–10 HU with RA−950 ( r = 0.63), 0–8 HU with %FEV1.0 ( r = −0.52) and 0–8 HU with FEV1.0 /FVC ( r = −0.61) per patient. Conclusion The iodine disturbance on DEpCT had a moderate correlation with the results of the PFTs and RA−950 , but further examination would be needed for evaluation of iodine distribution.