title: Association between RT-induced changes in lung tissue density and global lung function.
abstract: OBJECTIVE
  To assess the association between radiotherapy (RT)-induced changes in computed tomography (CT)-defined lung tissue density and pulmonary function tests (PFTs).
  
  
  METHODS
  Patients undergoing incidental partial lung RT were prospectively assessed for global (PFTs) and regional (CT and single photon emission CT [SPECT]) lung function before and, serially, after RT. The percent reductions in the PFT and the average changes in lung density were compared (Pearson correlations) in the overall group and subgroups stratified according to various clinical factors. Comparisons were also made between the CT- and SPECT-based computations using the Mann-Whitney U test.
  
  
  RESULTS
  Between 1991 and 2004, 343 patients were enrolled in this study. Of these, 111 patients had a total of 203 concurrent post-RT evaluations of changes in lung density and PFTs available for the analyses, and 81 patients had a total of 141 concurrent post-RT SPECT images. The average increases in lung density were related to the percent reductions in the PFTs, albeit with modest correlation coefficients (range, 0.20-0.43). The analyses also indicated that the association between lung density and PFT changes is essentially equivalent to the corresponding association with SPECT-defined lung perfusion.
  
  
  CONCLUSIONS
  We found a weak quantitative association between the degree of increase in lung density as defined by CT and the percent reduction in the PFTs.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA.
authors.forename: Jinli
authors.initials: J
authors.lastname: Ma
authors.forename: Junan
authors.initials: J
authors.lastname: Zhang
authors.forename: Sumin
authors.initials: S
authors.lastname: Zhou
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Hubbs
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Foltz
authors.forename: Donna R
authors.initials: DR
authors.lastname: Hollis
authors.forename: Kim L
authors.initials: KL
authors.lastname: Light
authors.forename: Terence Z
authors.initials: TZ
authors.lastname: Wong
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Kelsey
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Marks
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000528:radiation effects*; D008175:Lung Neoplasms / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011832:Radiation Injuries / Q000473:pathology* / Q000503:physiopathology*; D011879:Radiotherapy Dosage; D012129:Respiratory Function Tests; D018709:Statistics, Nonparametric; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D055815:Young Adult