title: Comparison of spirometric-gated and -ungated HRCT in COPD.
abstract: OBJECTIVE
  The purpose of this work was to evaluate feasibility of spirometric-gated high-resolution computed tomography (HRCT) in patients with chronic obstructive pulmonary disease (COPD) and to compare the lung density CT measurements obtained with and without spirometric control of lung volume.
  
  
  METHODS
  Twenty-nine patients with COPD underwent pulmonary function tests and spirometric-gated (3 slices at 10% and 90% of vital capacity) and -ungated (12 slices at maximum expiration and inspiration) HRCT in the same day. Four lung density measurements (inspiratory pixel index, expiratory pixel index, inspiratory and expiratory mean lung density) derived from gated and ungated acquisitions were compared using the nonparametric Wilcoxon test, the line of equality, and the Bland and Altman test.
  
  
  RESULTS
  The vital capacity measured at pulmonary function tests and on the CT table showed a substantial agreement. All but one patient completed the gated and ungated examination, but only 8 (28%) of 28 patients reached the expiratory and inspiratory gating level for CT acquisitions at the first attempt. Only the inspiratory mean lung density derived from the 3 gated and 12 ungated slices showed borderline agreement. Other CT measurements, and notably all those from the 3 gated and ungated scans, acquired at the same anatomic level, did not agree.
  
  
  CONCLUSIONS
  Although the procedure can be difficult for individual patients, spirometric gating significantly influences the lung density CT measurements and might improve standardization of CT evaluation of COPD.
authors.affiliation: Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Pisa, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Moroni
authors.forename: Mario
authors.initials: M
authors.lastname: Mascalchi
authors.forename: Gianna
authors.initials: G
authors.lastname: Camiciottoli
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bartolucci
authors.forename: Fabio
authors.initials: F
authors.lastname: Falaschi
authors.forename: Luigi
authors.initials: L
authors.lastname: Battolla
authors.forename: Ilaria
authors.initials: I
authors.lastname: Orlandi
authors.forename: Massimo
authors.initials: M
authors.lastname: Pistolesi
authors.forename: Natale
authors.initials: N
authors.lastname: Villari
mesh_terms: D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging*; D012129:Respiratory Function Tests; D013147:Spirometry; D014057:Tomography, X-Ray Computed / Q000379:methods*