title: Validation study of an interpolation method for calculating whole lung volumes and masses from reduced numbers of CT-images in ponies.
abstract: Quantitative computer tomographic analysis (qCTA) is an accurate but time intensive method used to quantify volume, mass and aeration of the lungs. The aim of this study was to validate a time efficient interpolation technique for application of qCTA in ponies. Forty-one thoracic computer tomographic (CT) scans obtained from eight anaesthetised ponies positioned in dorsal recumbency were included. Total lung volume and mass and their distribution into four compartments (non-aerated, poorly aerated, normally aerated and hyperaerated; defined based on the attenuation in Hounsfield Units) were determined for the entire lung from all 5 mm thick CT-images, 59 (55-66) per animal. An interpolation technique validated for use in humans was then applied to calculate qCTA results for lung volumes and masses from only 10, 12, and 14 selected CT-images per scan. The time required for both procedures was recorded. Results were compared statistically using the Bland-Altman approach. The bias ± 2 SD for total lung volume calculated from interpolation of 10, 12, and 14 CT-images was -1.2 ± 5.8%, 0.1 ± 3.5%, and 0.0 ± 2.5%, respectively. The corresponding results for total lung mass were -1.1 ± 5.9%, 0.0 ± 3.5%, and 0.0 ± 3.0%. The average time for analysis of one thoracic CT-scan using the interpolation method was 1.5-2 h compared to 8 h for analysis of all images of one complete thoracic CT-scan. The calculation of pulmonary qCTA data by interpolation from 12 CT-images was applicable for equine lung CT-scans and reduced the time required for analysis by 75%.
authors.affiliation: Anaesthesiology and Perioperative Intensive Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Wien, Austria. Electronic address: heidi.reich@vetmeduni.ac.at.
authors.forename: H
authors.initials: H
authors.lastname: Reich
authors.affiliation: Anaesthesiology and Perioperative Intensive Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Wien, Austria.
authors.forename: Y
authors.initials: Y
authors.lastname: Moens
authors.affiliation: Anaesthesiology and Perioperative Intensive Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Wien, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Braun
authors.affiliation: Diagnostic Imaging, Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Wien, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Kneissl
authors.affiliation: Department of Anaesthesiology and Intensive Care, University Hospital Leipzig, Liebigstr.20, 04103 Leipzig, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Noreikat
authors.affiliation: Department of Anaesthesiology and Intensive Care, University Hospital Leipzig, Liebigstr.20, 04103 Leipzig, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Reske
mesh_terms: D000818:Animals; D006736:Horses; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008168:Lung / Q000000981:diagnostic imaging / Q000502:physiology*; D008176:Lung Volume Measurements / Q000662:veterinary*; D015203:Reproducibility of Results; D013990:Tidal Volume; D014057:Tomography, X-Ray Computed / Q000662:veterinary*
keywords: Anaesthetised ponies; Interpolation validation; Lung volumes and masses; Quantitative imaging; Thoracic computed tomography