title: Spirometric-gated computed tomography quantitative evaluation of lung emphysema in chronic obstructive pulmonary disease: a comparison of 3 techniques.
abstract: OBJECTIVE
  To compare the quantitative assessment of pulmonary emphysema with spirometric-gated computed tomography (gated CT) using 3 different acquisition techniques and to determine if low-current spiral CT could be used effectively to quantitate emphysema.
  
  
  METHODS
  Eleven patients with chronic obstructive pulmonary disease (COPD) underwent gated CT and pulmonary function tests (PFTs). Spiral whole-lung 10-mm collimation acquisitions at standard (146 mAs) and low (43 mAs) current and sequential 3-slice 1-mm collimation high-resolution computed tomography (HRCT) acquisitions at standard current were obtained at 90% of the patient's vital capacity. The mean lung density (MLD) and the pixel index (PI) derived from the 3 data sets were compared using one-way analysis of variance and correlated with PFTs using linear regression. Moreover, the radiation dose associated with each technique was measured.
  
  
  RESULTS
  The MLDs were not significantly different. The PIs calculated from the standard- and low-current spiral acquisitions were similar, and both were significantly different from that of HRCT. The MLDs correlated with the PFTs in standard-current spiral and HRCT but not in low-current spiral acquisitions, whereas the PIs correlated with the PFTs in all 3 techniques. High-resolution computed tomography implied the lowest dose (0.08 mSv) compared with low-current (1.2 mSv) and standard-current (4 mSv) spiral techniques.
  
  
  CONCLUSIONS
  Low- and standard-dose spiral CT provides similar lung density data in COPD. The combination of low-dose whole-lung spiral CT and 3-slice HRCT represents the best compromise between the amount of information provided and radiation exposure to the patient and could be substituted for standard-dose spiral CT for quantitative evaluation of COPD.
authors.affiliation: Department of Clinical Physiopathology, University of Florence, Florence, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Orlandi
authors.forename: Chiara
authors.initials: C
authors.lastname: Moroni
authors.forename: Gianna
authors.initials: G
authors.lastname: Camiciottoli
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bartolucci
authors.forename: Giacomo
authors.initials: G
authors.lastname: Belli
authors.forename: Natale
authors.initials: N
authors.lastname: Villari
authors.forename: Mario
authors.initials: M
authors.lastname: Mascalchi
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D005652:Functional Residual Capacity / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008297:Male; D011653:Pulmonary Diffusing Capacity / Q000502:physiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement; D013147:Spirometry; D036542:Tomography, Spiral Computed / Q000379:methods*; D014797:Vital Capacity / Q000502:physiology