BACKGROUND: This article presents a novel methodological approach to evaluate images of aerosol deposition taken with PET-CT cameras. Traditionally, Black-or-White (BW) Regions of Interest (ROIs) are created to cover Anatomical Regions (ARs) segmented from the high-resolution CT. Such ROIs do not usually consider blurring effects due to limited spatial resolution or breathing motion, and do not consider uncertainty in the AR position within the PET image. The new methodology presented here (Grayscale) addresses these issues, allows estimates of aerosol deposition within ARs, and expresses the deposition in terms of Tissue Dosing (in the lung periphery) and Inner Surface Concentration (in the larger airways). METHODS: Imaging data included a PET deposition image acquired during breathing and two CT scans acquired during breath holds at different lung volumes. The lungs were segmented into anatomically consistent ARs to allow unbiased comparisons across subjects and across lobes. The Grayscale method involves defining Voxel Influence Matrices (VIMs) to consider how average activity within each AR influences the measured activity within each voxel. The BW and Grayscale methods were used to analyze aerosol deposition in 14 bronchoconstricted asthmatics. RESULTS: Grayscale resulted in a closer description of the PET image than BW (p<0.0001) and exposed a seven-fold underestimation in measures of specific deposition. The Average Tissue Dosing was 2.11×10(-6) Total Lung Dose/mg. The average Inner Surface Concentration was 45×10(-6) Total Lung Dose/mm(2), with the left lower lobe having a lower ISC than lobes of the right lung (p<0.05). There was a strong lobar heterogeneity in these measures (COV=0.3). CONCLUSION: The Grayscale approach is an improvement over the BW approach and provides a closer description of the PET image. It can be used to characterize heterogeneous concentrations throughout the lung and may be important in translational research and in the evaluation of aerosol delivery systems.
BACKGROUND: This article presents a novel methodological approach to evaluate images of aerosol deposition taken with PET-CT cameras. Traditionally, Black-or-White (BW) Regions of Interest (ROIs) are created to cover Anatomical Regions (ARs) segmented from the high-resolution CT. Such ROIs do not usually consider blurring effects due to limited spatial resolution or breathing motion, and do not consider uncertainty in the AR position within the PET image. The new methodology presented here (Grayscale) addresses these issues, allows estimates of aerosol deposition within ARs, and expresses the deposition in terms of Tissue Dosing (in the lung periphery) and Inner Surface Concentration (in the larger airways). METHODS: Imaging data included a PET deposition image acquired during breathing and two CT scans acquired during breath holds at different lung volumes. The lungs were segmented into anatomically consistent ARs to allow unbiased comparisons across subjects and across lobes. The Grayscale method involves defining Voxel Influence Matrices (VIMs) to consider how average activity within each AR influences the measured activity within each voxel. The BW and Grayscale methods were used to analyze aerosol deposition in 14 bronchoconstricted asthmatics. RESULTS: Grayscale resulted in a closer description of the PET image than BW (p<0.0001) and exposed a seven-fold underestimation in measures of specific deposition. The Average Tissue Dosing was 2.11×10(-6) Total Lung Dose/mg. The average Inner Surface Concentration was 45×10(-6) Total Lung Dose/mm(2), with the left lower lobe having a lower ISC than lobes of the right lung (p<0.05). There was a strong lobar heterogeneity in these measures (COV=0.3). CONCLUSION: The Grayscale approach is an improvement over the BW approach and provides a closer description of the PET image. It can be used to characterize heterogeneous concentrations throughout the lung and may be important in translational research and in the evaluation of aerosol delivery systems.
Authors: John Fleming; Dale L Bailey; Hak-Kim Chan; Joy Conway; Philip J Kuehl; Beth L Laube; Stephen Newman Journal: J Aerosol Med Pulm Drug Deliv Date: 2012-12 Impact factor: 2.849
Authors: Stephen Newman; William D Bennett; Martyn Biddiscombe; Sunalene G Devadason; Myrna B Dolovich; John Fleming; Sabine Haeussermann; Claudius Kietzig; Philip J Kuehl; Beth L Laube; Knut Sommerer; Glyn Taylor; Omar S Usmani; Kirby L Zeman Journal: J Aerosol Med Pulm Drug Deliv Date: 2012-12 Impact factor: 2.849
Authors: Elliot Eliyahu Greenblatt; Tilo Winkler; Robert Scott Harris; Vanessa Jane Kelly; Mamary Kone; Ira Katz; Andrew R Martin; George Caillibotte; Jose Venegas Journal: J Aerosol Med Pulm Drug Deliv Date: 2015-05-15 Impact factor: 2.849
Authors: Luciana Alcoforado; Armèle Dornelas de Andrade; Joaquin L Herraiz; Simone Cristina Soares Brandão; Jacqueline de Melo Barcelar; James B Fink; Jose G Venegas Journal: J Aerosol Med Pulm Drug Deliv Date: 2018-04-19 Impact factor: 2.849
Authors: Elliot Eliyahu Greenblatt; Tilo Winkler; Robert Scott Harris; Vanessa Jane Kelly; Mamary Kone; Ira Katz; Andrew Martin; George Caillibotte; Dean R Hess; Jose G Venegas Journal: J Aerosol Med Pulm Drug Deliv Date: 2016-01-29 Impact factor: 2.849
Authors: Chantal Darquenne; John S Fleming; Ira Katz; Andrew R Martin; Jeffry Schroeter; Omar S Usmani; Jose Venegas; Otmar Schmid Journal: J Aerosol Med Pulm Drug Deliv Date: 2016-02-01 Impact factor: 2.849