title: High-resolution CT analysis of small peripheral lung adenocarcinomas revealed on screening helical CT.
abstract: OBJECTIVE
  The purpose of this study was to determine the correlation between high-resolution CT morphologic features of small peripheral lung adenocarcinomas and tumor growth patterns.
  
  
  METHODS
  We examined high-resolution CT morphologic features of 59 small, surgically resected peripheral lung adenocarcinomas (diameter, 6-20 mm) that were detected on screening for lung cancer using low-dose helical CT. Among these adenocarcinomas, 14 (24%) were visible and 45 (76%) were invisible on conventional chest radiography. The correlation between high-resolution CT morphologic features and tumor growth patterns was analyzed.
  
  
  RESULTS
  Sixteen (94%) of 17 type A (Noguchi's classification) adenocarcinomas appeared as nodules of pure ground-glass attenuation (high-resolution CT type I). Ten (71%) of 14 type B tumors appeared as heterogeneous, low-attenuation nodules (type II). Seven (29%) of 24 type C tumors appeared as nodules with ground-glass attenuation in the periphery and a high-density central zone (type III), and 12 (50%) of 24 type C tumors appeared as homogeneous nodules with soft-tissue density (type IV). Among tumors with a replacement growth pattern, the size and CT values of type C tumors were larger than those of type A or type B tumors (p < 0.05), whereas the percentage of ground-glass attenuation and retained air space in type C tumors was smaller than those in type A or type B tumors (p < 0.01). All (100%) four type D tumors appeared to be homogeneous nodules with soft-tissue density (type IV).
  
  
  CONCLUSIONS
  Small peripheral lung adenocarcinomas shown on CT exhibit four high-resolution CT patterns that corresponded to the histopathologic findings of different tumor growth patterns.
authors.affiliation: Department of Radiology, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto, 390 8621, Japan.
authors.forename: Z G
authors.initials: ZG
authors.lastname: Yang
authors.forename: S
authors.initials: S
authors.lastname: Sone
authors.forename: S
authors.initials: S
authors.lastname: Takashima
authors.forename: F
authors.initials: F
authors.lastname: Li
authors.forename: T
authors.initials: T
authors.lastname: Honda
authors.forename: Y
authors.initials: Y
authors.lastname: Maruyama
authors.forename: M
authors.initials: M
authors.lastname: Hasegawa
authors.forename: S
authors.initials: S
authors.lastname: Kawakami
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods*