Biomechanical CT metrics are associated with patient outcomes in COPD

COPDGene Investigators, Sandeep Bodduluri, Surya P Bhatt, Eric A Hoffman, John D Newell, Carlos H Martinez, Mark T Dransfield, Meilan K Han, Joseph M Reinhardt

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: Traditional metrics of lung disease such as those derived from spirometry and static single-volume CT images are used to explain respiratory morbidity in patients with COPD, but are insufficient. We hypothesised that the mean Jacobian determinant, a measure of local lung expansion and contraction with respiration, would contribute independently to clinically relevant functional outcomes.

METHODS: We applied image registration techniques to paired inspiratory-expiratory CT scans and derived the Jacobian determinant of the deformation field between the two lung volumes to map local volume change with respiration. We analysed 490 participants with COPD with multivariable regression models to assess strengths of association between traditional CT metrics of disease and the Jacobian determinant with respiratory morbidity including dyspnoea (modified Medical Research Council), St Georges Respiratory Questionnaire (SGRQ) score, 6-min walk distance (6MWD) and the Body Mass Index, Airflow Obstruction, Dyspnoea and Exercise Capacity (BODE) index, as well as all-cause mortality.

RESULTS: The Jacobian determinant was significantly associated with SGRQ (adjusted regression coefficient β=-11.75,95% CI -21.6 to -1.7; p=0.020), and with 6MWD (β=321.15, 95% CI 134.1 to 508.1; p<0.001), independent of age, sex, race, body mass index, FEV1, smoking pack-years, CT emphysema, CT gas trapping, airway wall thickness and CT scanner type. The mean Jacobian determinant was also independently associated with the BODE index (β=-0.41, 95% CI -0.80 to -0.02; p=0.039) and mortality on follow-up (adjusted HR=4.26, 95% CI 0.93 to 19.23; p=0.064).

CONCLUSIONS: Biomechanical metrics representing local lung expansion and contraction improve prediction of respiratory morbidity and mortality and offer additional prognostic information beyond traditional measures of lung function and static single-volume CT metrics.

TRIAL REGISTRATION NUMBER: NCT00608764; Post-results.

Original languageEnglish
Pages (from-to)409-414
Number of pages6
JournalThorax
Volume72
Issue number5
DOIs
Publication statusPublished - May 2017
Externally publishedYes

Keywords

  • Aged
  • Aged, 80 and over
  • Airway Obstruction
  • Body Mass Index
  • Cause of Death
  • Dyspnea
  • Female
  • Follow-Up Studies
  • Humans
  • Imaging, Three-Dimensional
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Phenotype
  • Physical Endurance
  • Prognosis
  • Pulmonary Disease, Chronic Obstructive
  • Quality of Life
  • Respiratory Function Tests
  • Respiratory Mechanics
  • Software
  • Surveys and Questionnaires
  • Tomography, X-Ray Computed
  • Journal Article

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