title: Detection of pulmonary metastases with multi-detector row CT scans of 5-mm nominal section thickness: autopsy lung study.
abstract: OBJECTIVE
  To determine the effect of changing pitch and collimation on depiction of pulmonary metastases on scans of 5-mm section thickness obtained with multi-detector row computed tomography (CT) compared with those obtained with single-detector row CT.
  
  
  METHODS
  In five autopsy lungs, 1,013 metastatic 0.5-30.0-mm nodules were detected at helical CT with 1-mm collimation and histopathologically diagnosed as metastases. Each nodule was numbered, and its localization was recorded as the standard for subsequent studies. Four types of scans of 5-mm section thickness were obtained with multi-detector row CT and four sets of helical pitch and table speed, respectively, as follows: set A, 3:1 and 7.5 mm per rotation; set B, 6:1 and 15 mm per rotation; set C, 6:1 and 30 mm per rotation; set D, conventional and 5-mm interval. Conventional helical CT scans (set E) were obtained with 5-mm collimation at single-detector row CT. Two independent observers evaluated the five sets of CT scans.
  
  
  RESULTS
  Acquisition times for sets A-D, respectively, were 1.9, 3.8, 7.5, and 1.5 times faster than they were for set E. The mean numbers of detected nodules were 671 (66%) in set A, 661 (65%) in set B, 678 (67%) in set C, 654 (65%) in set D, and 656 (65%) in set E; there was no significant difference in the number of detected nodules among the five sets (P =.997, McNemar test and Bonferroni equation).
  
  
  CONCLUSIONS
  Regardless of varying pitch or detector collimation, multi- and single-detector row CT scans obtained with 5-mm section thickness have almost the same ability to depict pulmonary metastases and are equivalent.
authors.affiliation: Department of Radiology, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. koz@radiol.med.osaka-u.ac.jp
authors.forename: Takenori
authors.initials: T
authors.lastname: Kozuka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Johkoh
authors.forename: Seiki
authors.initials: S
authors.lastname: Hamada
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Naito
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Tomiyama
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Koyama
authors.forename: Naoki
authors.initials: N
authors.lastname: Mihara
authors.forename: Osamu
authors.initials: O
authors.lastname: Honda
authors.forename: Hironobu
authors.initials: H
authors.lastname: Nakamura
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kudo
mesh_terms: D001344:Autopsy; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D036542:Tomography, Spiral Computed / Q000379:methods*