Quantitative Lung Function Imaging for Detection of Parenchymal Lung Abnormalities Using Four Dimensional Computed Tomography Scan

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Rationale: 4DCT-derived ventilation (CT-V) imaging recovers changes in local tissue volumes induced by tidal respiratory motion. We have previously shown good correlation between CT-V and lung function parameters. However, there are no previous studies evaluating its clinical application to detect ventilation defects in patients with parenchymal lung abnormalities. Methods: We included 55 patients who had CT-V measured prospectively from the control arm of “4DCT perfusion defects in pulmonary embolism study”. Parenchymal lung abnormalities (PLA) were adjudicated from corresponding CT angiogram that was performed simultaneously with 4DCT and included consolidation, atelectasis, pulmonary edema, ground glass opacities, interstitial lung disease, emphysema or lung mass. CT-V scores between inhalation and exhalation were calculated at a voxel level on each lung using the “Integrated Jacobian Formulation” (IJV) CT-V method. Results: Patients with PLA were more likely to be smokers compared to those without (71% vs. 38.2%, p 0.02).Patients without PLA had a higher BMI (35.73 vs. 30.27 kg/m2 , p 0.01) and were less likely to have a history of emphysema or lung cancer (Figure-1). The mean ventilation scores were significantly higher in patients without PLA in both right (1.2384 vs. 1.1713, p 0.004) and left lungs (1.2230 vs. 1.1641, p 0.02) compared to those with PLA. On multivariate regression analysis after adjusting for all other factors, the only significant variable influencing CT-V scores was presence of PLA [Right: p =0.03, Left: p =0.01]. Conclusion: Patients without PLA had significantly higher CT-V scores than those with. Our study for the first time shows the clinical utility of 4DCT derived ventilation metrics applied to a general population can accurately quantify lung ventilation at a voxel level. CT-V using IJV method has wide implication for assessment of progression, early detection and therapeutic effects of medications in patients with parenchymal lung abnormalities.




American Thoracic Society 2019 International Conference, May 17-22, 2019. Dallas Tx. Meeting Abstract: A108