Fleming John, Conway Joy, Majoral Caroline, Katz Ira, Caillibotte Georges, Pichelin Marine, Montesantos Spyridon, Bennett Michael
1 National Institute of Health Research Biomedical Research Unit in Respiratory Disease , Southampton, United Kingdom .
2 Department of Medical Physics and Bioengineering, University Hospital Southampton NHS Foundation Trust , Southampton, United Kingdom .
J Aerosol Med Pulm Drug Deliv. 2015 Dec;28(6):432-51. doi: 10.1089/jamp.2014.1191. Epub 2015 Apr 10.
Computer modeling is used to predict inhaled aerosol deposition in the lung based on definition of the aerosol characteristics and the breathing pattern and airway anatomy of the subject. Validation of the models is limited by the lack of detailed experimental data. Three-dimensional imaging provides an opportunity to address this unmet need.
Radioactive aerosol was administered to six male asthmatic subjects on two occasions under carefully monitored input conditions. Input parameters varied in particle size, depth of breathing, and carrier gas. The aerosol distribution was measured by combined single photon emission computed tomography and x-ray computer tomography (SPECT/CT) and airway anatomy by high resolution CT. The deposition distribution was measured by both a 2D and 3D analysis and described in terms of the percentage of inhaled aerosol deposited in sections of the respiratory tract and in both spatial and anatomical subdivisions within each lung. The percentage deposition in the conducting airways was also assessed by 24 h clearance.
A set of imaging data of aerosol deposition has thus been produced in which the input parameters of inhalation are well described. The results in asthmatics were compared to previous measurements in healthy controls using an identical inhalation protocol. The percentages of deposition in extra-thoracic and thoracic compartments of the airways were not significantly affected by disease, but the regional pulmonary deposition pattern was, with asthma leading to increased deposition in the conducting airways.
The dataset acquired in this study will be useful in validating computer models of aerosol deposition in asthmatic subjects. Asthma did not affect the fraction of inhaled aerosol depositing in the lungs, but gave rise to a more central deposition pattern. The use of 3D SPECT imaging in combination with 24 h clearance measurements enables differentiation of deposition between bronchial and bronchiolar airways.
计算机建模用于根据气溶胶特征、呼吸模式和受试者气道解剖结构来预测肺部吸入气溶胶的沉积情况。由于缺乏详细的实验数据，模型的验证受到限制。三维成像为满足这一未被满足的需求提供了契机。
在仔细监测输入条件下，对6名男性哮喘患者分两次给予放射性气溶胶。输入参数在粒径、呼吸深度和载气方面有所不同。通过单光子发射计算机断层扫描与X射线计算机断层扫描（SPECT/CT）联合测量气溶胶分布，通过高分辨率CT测量气道解剖结构。沉积分布通过二维和三维分析进行测量，并以呼吸道各节段以及每个肺内的空间和解剖亚区域中吸入气溶胶沉积的百分比来描述。还通过24小时清除率评估传导气道中的沉积百分比。
由此产生了一组气溶胶沉积的成像数据，其中吸入的输入参数得到了很好的描述。使用相同的吸入方案，将哮喘患者的结果与先前健康对照者的测量结果进行了比较。气道胸外和胸内部分的沉积百分比未受疾病显著影响，但区域肺部沉积模式受到影响，哮喘导致传导气道中的沉积增加。
本研究获得的数据集将有助于验证哮喘患者气溶胶沉积的计算机模型。哮喘并未影响吸入气溶胶在肺部沉积的比例，但导致了更集中的沉积模式。结合使用三维SPECT成像和24小时清除率测量能够区分支气管和细支气管气道中的沉积情况。
