Final Report: X-ray CT-based Assessment of Variations in Human Airway Geometry: Implications for Evaluation of Particle Deposition and Dose to Different Populations

EPA Grant Number: R827351C002
Subproject: this is subproject number 002 , established and managed by the Center Director under grant R827351
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EPA NYU PM Center: Health Risks of PM Components
Center Director: N/A
Title: X-ray CT-based Assessment of Variations in Human Airway Geometry: Implications for Evaluation of Particle Deposition and Dose to Different Populations
Investigators: Cohen, Beverly S. , Hoffman, Eric
Institution: New York University School of Medicine , University of Iowa
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 31, 2005 (Extended to May 31, 2006)
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air

Objective:

To address the paucity of data regarding particulate matter (PM) deposition in the lungs of people with pre-existing pulmonary disease and the normal elderly, subpopulations which may be at special risk, this project investigated the potential for retrieval of morphometric data from three-dimensional images of tracheobronchial airways obtained in vivo by x-ray Computerized Tomography (CT). The study also explored the potential for the use of stereolithography (STL) to produce hollow airway casts of normal and abnormal lung airways for the experimental determination of site-specific deposition and for experimental verification of particle deposition models. The project was a collaboration between the extensive imaging expertise at the University of Iowa and New York University (NYU) PM Center particle deposition expertise.

A volumetric rendering of the interior surface of a hollow airway cast (used in previous studies at NYU) was generated, producing a surface representation of the airway tree. These three-dimensional images were then converted to a STL file format required for the rapid prototyping of airway casts. Close concordance was seen between the original hollow airway cast and the STL produced replicate. The casting process was subsequently converted to utilize a water soluble material to build supporting structures. Thin multi-slice helical CT scanning allows the acquisition of high-resolution volumetric image data sets of the lung in a breath-hold or at multiple phases within a respiratory cycle. From these scans, hollow airway casts that include 5 or 6 bronchial generations can be created.

Iowa collaborators continued to work on the development of sheep models for the testing of various measures of pulmonary perfusion, regional ventilation, airway structure and distensibility, diaphragm and rib cage mechanics, etc. We fine-tuned our methods of respiratory gating and succeeded in developing methodology that allows us to gate image acquisition very accurately to an inductance plethysmographic (Respitrace) signal, and acquire volumetric images of the lung at multiple points within the respiratory cycle over a period of 30 cycles. Significant advancements in computerized analysis have been made in the areas of lung, lobe and airway segmentation, airway tree matching, and lung feature matching. A set of reproducible feature points are first identified, including airway branching points, for each CT image to establish correspondences across subjects.

We have tried to develop a suitable monodisperse radio-opaque test aerosol. We have x-ray tested common contrast media to determine the smallest layer that can be distinguished from a unit density background, but results to date are not satisfactory.

Summary/Accomplishments (Outputs/Outcomes):

This project developed a computational capacity to create a 3-D computer model of lung airway dimensions from CT scans of an original cast model on which measurements had been made of airway branch diameter, length, and branching angle. We then demonstrated excellent agreement on measurements made from a silastic reproduction as compared with the original to assure accurate reproduction of these metrics. The process was utilized to obtain an image based on CT scanning, and then produce a tracheobronchial cast, from a living person. An aerosol suitable for CT scanning during inhalation in a live individual has not yet been developed.

Conclusions:

This project demonstrated for the first time that hollow airway casts can be produced from CT scans of the lungs of living individuals. The technique can be used to accurately replicate the airways of both healthy and diseased individuals, and also children who have undergone CT scanning of the lung. Dr. Hoffmann has a large database of patients of all ages who have undergone CT scanning for medical purposes. It includes individuals who demonstrated no lung disease as well as those with cancer, and various other lung pathologies. The database also includes standard medical data such as age, height and weight, symptoms, diagnosis, and results of related pulmonary testing. This will make it possible to examine deposition in healthy and diseased airways using replicate casts and realistic breathing parameters.

Technical Report:

Long Version of Final Report (PDF) (3 pp, 16.5 K, About PDF)

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this subproject

Supplemental Keywords:

tracheobronchial casts, airway models, human lung, particle deposition,, RFA, Health, PHYSICAL ASPECTS, Scientific Discipline, Air, ENVIRONMENTAL MANAGEMENT, particulate matter, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Physical Processes, Environmental Monitoring, Atmospheric Sciences, Risk Assessment, ambient air quality, atmospheric particulate matter, particulates, air toxics, atmospheric particles, chemical characteristics, toxicology, ambient air monitoring, acute lung injury, airborne particulate matter, environmental risks, exposure, epidemelogy, air pollution, aerosol composition, atmospheric aerosol particles, human exposure, PM, X-ray tomagraphy, airway contractile properties, exposure assessment

Relevant Websites:

Long Version of Final Report (PDF) (3 pp, 16.5 K, About PDF)
http://www.med.nyu.edu/environmental/ Exit
https://www.epa.gov/research-grants/

Progress and Final Reports:

Original Abstract
  • 1999 Progress Report
  • 2000 Progress Report
  • 2001 Progress Report
  • 2002 Progress Report
  • 2003 Progress Report
  • 2004

  • Main Center Abstract and Reports:

    R827351    EPA NYU PM Center: Health Risks of PM Components

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827351C001 Exposure Characterization Error
    R827351C002 X-ray CT-based Assessment of Variations in Human Airway Geometry: Implications for Evaluation of Particle Deposition and Dose to Different Populations
    R827351C003 Asthma Susceptibility to PM2.5
    R827351C004 Health Effects of Ambient Air PM in Controlled Human Exposures
    R827351C005 Physicochemical Parameters of Combustion Generated Atmospheres as Determinants of PM Toxicity
    R827351C006 Effects of Particle-Associated Irritants on the Cardiovascular System
    R827351C007 Role of PM-Associated Transition Metals in Exacerbating Infectious Pneumoniae in Exposed Rats
    R827351C008 Immunomodulation by PM: Role of Metal Composition and Pulmonary Phagocyte Iron Status
    R827351C009 Health Risks of Particulate Matter Components: Center Service Core
    R827351C010 Lung Hypoxia as Potential Mechanisms for PM-Induced Health Effects
    R827351C011 Urban PM2.5 Surface Chemistry and Interactions with Bronchoalveolar Lavage Fluid (BALF)
    R827351C012 Subchronic PM2.5 Exposure Study at the NYU PM Center
    R827351C013 Long Term Health Effects of Concentrated Ambient PM2.5
    R827351C014 PM Components and NYC Respiratory and Cardiovascular Morbidity
    R827351C015 Development of a Real-Time Monitoring System for Acidity and Soluble Components in Airborne Particulate Matter
    R827351C016 Automated Real-Time Ambient Fine PM Monitoring System