title: Morphological progression of emphysema on thin-section CT: Analysis of longitudinal change in the number and size of low-attenuation clusters.
abstract: OBJECTIVE
  To evaluate morphological changes in the number and size of low-attenuation clusters on computed tomography (CT) in patients with emphysema.
  
  
  METHODS
  In 27 patients who had follow-up CT scans for 6 months or greater, initial 27 scans and follow-up 39 scans were analyzed. The number per slice (LAN/s) and mean size (LAS) of low-attenuation clusters less than -950 HU, and total low-attenuation area below -950 HU per slice (LAA-950/s) were calculated.
  
  
  RESULTS
  LAS and LAA-950/s were significantly increased over time. No significant correlation was found between LAN/s and follow-up period. LAS increased in 37 of 39 (95%) follow-up scans, whereas LAN/s decreased in 17 of 39 (44%) follow-up scans.
  
  
  CONCLUSIONS
  On the morphological progression of emphysema, the mean size of low-attenuation clusters was significantly increased during the follow-up period, whereas no significant correlation was found between the number of low-attenuation clusters and follow-up period.
authors.affiliation: Department of Radiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Kawasaki City, Kanagawa, 216-8511, Japan. shinma@d9.dion.ne.jp
authors.forename: Shin
authors.initials: S
authors.lastname: Matsuoka
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kurihara
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Yagihashi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nakajima
mesh_terms: D000368:Aged; D018450:Disease Progression; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000473:pathology; D012307:Risk Factors; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*