Quantitative CT evaluation in patients with combined pulmonary fibrosis and emphysema: correlation with pulmonary function.
OBJECTIVE
The purpose of this study was to evaluate the correlations between objective quantitative computed tomography (CT) measurements of the extent of emphysematous and fibrotic lesions and the results of pulmonary function tests (PFTs) in patients with combined pulmonary fibrosis and emphysema (CPFE).


METHODS
This study involved 43 CPFE patients who underwent CT and PFTs. The extent of emphysematous lesions was obtained by calculating the percentage of low attenuation area (%LAA) values lower than -950 Hounsfield units (HU). Fibrotic lesions were defined as high attenuation area (HAA) using thresholds with pixels between 0 and -700 HU, and the extent of fibrosis was obtained by calculating the percentage of HAA (%HAA). The correlations of %LAA and %HAA with PFTs were evaluated by the Spearman rank correlation coefficients and multiple linear regression analysis.


RESULTS
A significant negative correlation was found between %HAA and diffusing capacity of the lung for carbon monoxide (DLco) %predicted (ρ = -0.747; P < .001), whereas no significant correlation was found between %LAA and DLco %predicted. On multiple linear regression analysis, although the %HAA and %LAA were independent contributors to DLco %predicted, the predictive power of %HAA was superior to that of %LAA.


CONCLUSIONS
In CPFE, the extent of fibrosis has a more significant impact on DLco than emphysema.
Department of Radiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki 216-8511, Kanagawa, Japan. Electronic address: shin4114@mac.com.
Shin
S
Matsuoka
Department of Radiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki 216-8511, Kanagawa, Japan; Department of Radiology, Graduate School of Medical Science, University of the Ryukyu, Nishihara, Ryukyu, Japan.
Tsuneo
T
Yamashiro
Department of Radiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki 216-8511, Kanagawa, Japan.
Shoichiro
S
Matsushita
Department of Radiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki 216-8511, Kanagawa, Japan.
Akiyuki
A
Kotoku
Department of Radiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki 216-8511, Kanagawa, Japan.
Atsuko
A
Fujikawa
Department of Radiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki 216-8511, Kanagawa, Japan.
Kunihiro
K
Yagihashi
Department of Radiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki 216-8511, Kanagawa, Japan.
Yasuo
Y
Nakajima
D000368:Aged; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D011237:Predictive Value of Tests; D011656:Pulmonary Emphysema / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011658:Pulmonary Fibrosis / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
CT quantification; Combined pulmonary fibrosis and emphysema; computed tomography; densitometry