title: Computed tomography of the lung in the high-pitch mode: is breath holding still required?
abstract: OBJECTIVE
  To prospectively investigate whether the high-pitch mode (HPM) for computed tomography (CT) enables the diagnostic visualization of the lung parenchyma without suspended respiration.
  
  
  METHODS
  A total of 40 consecutive patients (age, 67 ± 11 years) underwent 128-slice dual-source CT of the chest including nonenhanced, arterial, and venous phase of contrast. CT was performed in the HPM with a pitch of 3.2 during continuous breathing (group A) and during breath-hold (group B), and at standard pitch of 1 during deep-inspiratory breath-hold (group C). The 3 protocols were scanned in a random order in each patient. Two blinded readers independently assessed the image quality of 5 regions in both the lungs using a semiquantitative 3-point score. Image noise was measured as the standard deviation of attenuation. Presence and size of pulmonary nodules were noted and measured on each CT dataset. Lung volume was measured using dedicated semi-automated segmentation software.
  
  
  RESULTS
  Interobserver agreement for image quality ratings was excellent (κ = 0.91). There were no significant differences in the number of lung regions having an image quality other than excellent between group A (2.5%) and B (1.5%, P = 0.48), whereas significantly less regions had impaired image quality in group B compared with group C (5.5%, P < 0.01). Image quality impairment in group C was because of breathing in 36% and cardiac pulsation in 64%. Image noise in group C (9 ± 2 HU) was significantly lower than that in group B (30 ± 2 HU, P < 0.001) whereas no significant difference was found between group A and B (P = 0.52). There were no significant differences for the depiction (P = 1.0) and size (P = 0.94) of lung nodules among the 3 modes. Average lung volume in group A was 75% ± 15% of that in deep inspiration (group B/C) being significantly smaller (P < 0.05). Estimated effective radiation doses in group C and group B were 5.8 ± 0.5 mSv and 1.6 ± 0.1 mSv, respectively.
  
  
  CONCLUSIONS
  CT of the lung can be accomplished using the HPM at a low radiation dose with a diagnostic image quality even without suspended respiration.
authors.affiliation: Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Stephan
authors.initials: S
authors.lastname: Baumueller
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.forename: Paul
authors.initials: P
authors.lastname: Stolzmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenfelder
authors.forename: Robert
authors.initials: R
authors.lastname: Goetti
authors.forename: Thomas
authors.initials: T
authors.lastname: Schertler
authors.forename: Andre
authors.initials: A
authors.lastname: Plass
authors.forename: Volkmar
authors.initials: V
authors.lastname: Falk
authors.forename: Gudrun
authors.initials: G
authors.lastname: Feuchtner
authors.forename: Hans
authors.initials: H
authors.lastname: Scheffel
authors.forename: Lotus
authors.initials: L
authors.lastname: Desbiolles
authors.forename: Sebastian
authors.initials: S
authors.lastname: Leschka
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008171:Lung Diseases / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009929:Organ Size; D012119:Respiration; D014057:Tomography, X-Ray Computed