Image Functional Modeling: Combining Lung Models with Imaging

Image Functional Modeling: Combining Lung Models with Imaging

Image Functional Modeling: Combining Lung Models with Imaging Modalities and Mechanical Measures BMES Conference Nora T. Tgavalekos, Jose G. Venegas, Mitchell Albert, Allison Bell, and K. R. Lutchen October 14, 2004 Asthma Stimuli Inflammatory mediators Cell activation (proinflammatory mediators: histamine) (Allergens,outdoor (mast cells, eosinophils, pollutants and viruses) neutrophils)

Airway Changes (inflammation, remodeling, bronchoconstriction) Airway Obstruction http://www.merckfrosst.ca/e/health/asthma/sum_01.html ? Size and Location ? Distribution Mechanical Heterogeneity in Asthma Which airways are most responsible for degradation in function and hyperresponsiveness? PET Imaging: Tracer Kinetics

Apnea Washout Time (secs) PET Imaging: Tracer Kinetics Apnea Washout Time (secs) PET Imaging apex Pre Challenge Post Challenge base

Images from Mass General Hospital Hyperpolarized 3He MRI Imaging Pre Challenge Post Challenge Images from Brigham and Womens Hospital Image-Functional Modeling (IFM) Goal: To synthesize the imaging and mechanical information in order to identify which airways are responsible for the degradation in the mechanics and ventilation distribution on a patient specific basis. Method: Combine the imaging and mechanical data with 3D anatomically consistent multi-scale lung models. Advancing 3D Models for Computation of Mechanical Function Impedance of a Single Airway

Z(n-1) Z(n) R(n)/2 I(n)/2 Cg(n) R(n)/2 I(n)/2 Zw(n) Tawhai et al, 1999 Airways Terminate on Alveoli with Viscoelastic Tissue Z(n-1- )

IFM: Mapping PET Ventilation Defects into 3D Model Pre Washout: Baseline Post Washout: Tracer Retention PET: IFM Application Baseline Post Challenge 0.6mm mm d<2.5 d< 0.9mm 0.9mm d< 0.6 mm d< 0.6 mm Resistance(cmH Resistance(cmH220/l/s)

0/l/s) 45 36 27 18 d <.6 mm Size Range of Allowable Closed 9 0 0 2 4 6

Percent of Baseline Airway Diameter0.3-2.5 Airways: mm. 100 open 88 80 d< .9 mm Elastance(cmH20/l) 300 60 200 40 d < 2.5 mm

100 20 0 0 2 4 6 Frequency (Hz) 88 0 closed Hyperpolarized MRI : IFM Application Image and Model Based Ventilation Images PET Based

Model Based Ventilation Spectrum: Fraction of Baseline Ventilation 2 over 1.6 1.2 .8 normal .4 0 under Summary We identified constriction conditions, which are consistent with both the lung mechanics and imaging information for 4 asthmatics: Maximum airway size for closures:

Mean airway sizes affected: Constriction Conditions: 0.9 -2.4 mm <1 mm and below = 60% , SD= 20% The IFM paradigm provides a platform for multi-scale sensitivity analysis regarding how the integrated components of lung structure determined the degradation in function during airway disease. Acknowledgements BU Respiratory Lab Anesthesia & Critical Care,MGH Kenneth R. Lutchen Jose G. Venegas Carissa Bellardine

R. Scott Harris Derek Affonce Marcos Vidal Melo Brian Szender Allison Bell Mike Hamilton Jen Kenyon Guido Musch Tilo Winkler Giacomo Bellani Adam LaPrad Funding Sources AAUW Selected Professions Fellowship NIH BMES University of Auckland, New Zealand Merryn Tawhai

Brigham and Womens Hospital Mitchell Albert Yang- Sheng Tzeng PET: IFM Application Percent of Baseline Airway Diameter Baseline Post Challenge 0.6mm mm d<2.5 d< 0.9mm 0.9mm d< 0.6 mm d< 0.6 mm Resistance(cmH Resistance(cmH220/l/s)

0/l/s) 45 36 27 d <.6 mm 80 18 60 Size Range of Allowable d< Closed Airways: 0.3-2.5 mm. .9 mm 9 0

0 2 4 6 40 88 20 300 Elastance(cmH20/l) 100 open d < 2.5 mm 200

100 0 0 2 4 6 Frequency (Hz) 88 0 closed

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