title: CT quantification of large opacities and emphysema in silicosis: correlations among clinical, functional, and radiological parameters.
abstract: BACKGROUND
  The assessment of the extent of silicosis on chest radiographs is subjective and could be more standardized by using computed tomography (CT) quantification methods. We propose a semiautomatic method of quantifying the anatomical lung damage (LD) (the sum of the emphysema and large opacities volumes) measured by CT densitovolumetry in complicated silicosis.
  
  
  METHODS
  Twenty-three nonsmokers with complicated silicosis were included. Large opacities were recorded as size A, B, or C according to the size of the opacities on chest radiographs. Pulmonary function tests (PFT) were assessed by spirometry and the carbon monoxide diffusion capacity. Total lung capacity (TLC) was measured by helium dilution, and total lung volume (TLV) was measured by CT quantification (TLVct). CT images were postprocessed using CT densitovolumetry to measure the TLVct, large opacities volume, emphysema volume (EV), and emphysema index (EI).
  
  
  RESULTS
  Significant correlations were observed between the EV and the forced vital capacity (r = 0.41, p = 0.04), TLC (r = 0.44, p = 0.03), and residual volume (RV) (r = 0.49, p = 0.01). A correlation also was observed between the LD% and RV (r = 0.43, p = 0.03) and between the LD and RV (r = 0.47, p = 0.02).
  
  
  CONCLUSIONS
  The PFT findings were correlated with the EV, EI, LD, and LD%, but they were not correlated with the large opacities volume. These results suggest that the emphysema volume, more than the large opacities volume, is responsible for functional impairment in patients with complicated silicosis.
authors.affiliation: Universidade Federal Fluminense, Rua Domingues de Sá número 431. Apt. 701, Icaraí, Niterói, Rio de Janeiro, CEP: 24.220-090, Brazil, marcoscscmed@yahoo.com.br.
authors.forename: Marcos César Santos
authors.initials: MC
authors.lastname: de Castro
authors.forename: Angela Santos
authors.initials: AS
authors.lastname: Ferreira
authors.forename: Klaus Loureiro
authors.initials: KL
authors.lastname: Irion
authors.forename: Bruno
authors.initials: B
authors.lastname: Hochhegger
authors.forename: Agnaldo José
authors.initials: AJ
authors.lastname: Lopes
authors.forename: Guilhermo Coca
authors.initials: GC
authors.lastname: Velarde
authors.forename: Gláucia
authors.initials: G
authors.lastname: Zanetti
authors.forename: Edson
authors.initials: E
authors.lastname: Marchiori
mesh_terms: D000328:Adult; D000368:Aged; D001331:Automation; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008176:Lung Volume Measurements / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011653:Pulmonary Diffusing Capacity; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011857:Radiographic Image Interpretation, Computer-Assisted; D012720:Severity of Illness Index; D012829:Silicosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D013147:Spirometry; D036542:Tomography, Spiral Computed; D014797:Vital Capacity