An analysis algorithm for measuring airway lumen and wall areas from high-resolution computed tomographic data.

High-resolution computed tomography (HRCT) has been used to examine airway narrowing. We developed an automated computed tomographic image analysis algorithm (computed tomographic airway morphometry; CTAM) to measure airway lumen area (Ai ), airway wall area (Awa), and airway angle of orientation. Tubes of varying size were embedded in Styrofoam and then scanned at angles between 0 degrees and 50 degrees to assess the accuracy of measurements made with CTAM. Two excised pig lungs were fixed in inflation, sectioned, and scanned. Ai and Awa were measured planimetrically from the cut surfaces to optimize CTAM measurement parameters. In CTAM, Ai was defined according to an airway-size-dependent threshold value, and total Awa was determined through a score-guided erosion method. Results were compared with measurements made through a previously validated method (manual method). CTAM provided accurate measurements of the tubes' Ai values at all angles; Awa was overestimated in direct relation to airway size. The manual method underestimated Ai and overestimated Awa in a manner directly related to airway size as well as to airway angle of orientation. In the excised lung, the mean errors of Ai and Awa measurements made with CTAM were 0.52 +/- 0.24 mm(2) and 0.17 +/- 0.32 mm(2) (mean +/- SEM), respectively. Ai errors with the manual method were similar, but Awa was overestimated to a greater degree (6.3 +/- 0.38 mm(2); p < 0.01) and the error was proportional to Awa (r = 0.64; p < 0.01). CTAM allows accurate measurements of airway dimensions and angle of orientation.

[1]  P. Paré,et al.  Human airway narrowing measured using high resolution computed tomography. , 1996, American journal of respiratory and critical care medicine.

[2]  G Gamsu,et al.  CT of a bronchial phantom. Factors affecting appearance and size measurements. , 1984, Investigative radiology.

[3]  P. Paré,et al.  Small airways dimensions in asthma and in chronic obstructive pulmonary disease. , 1993, The American review of respiratory disease.

[4]  J D Newell,et al.  Uncomplicated asthma in adults: comparison of CT appearance of the lungs in asthmatic and healthy subjects. , 1993, Radiology.

[5]  R. Brown,et al.  Individual canine airways responsiveness to aerosol histamine and methacholine in vivo. , 1998, American journal of respiratory and critical care medicine.

[6]  P. Paré,et al.  In vivo and in vitro correlation of trachealis muscle contraction in dogs. , 1992, Journal of applied physiology.

[7]  D. Lynch,et al.  Quantitative computed tomography detects air trapping due to asthma. , 1994, Chest.

[8]  J. Hogg,et al.  Morphologic determinants of airway responsiveness in chronic smokers. , 1996, American journal of respiratory and critical care medicine.

[9]  J. Bousquet,et al.  Chest radiography and high resolution computed tomography of the lungs in asthma. , 1992, The American review of respiratory disease.

[10]  J Bousquet,et al.  Measurement of the internal size of bronchi using high resolution computed tomography (HRCT) , 1994, The European respiratory journal.

[11]  A. James,et al.  The structure of large and small airways in nonfatal and fatal asthma. , 1993, The American review of respiratory disease.

[12]  D. Altman,et al.  STATISTICAL METHODS FOR ASSESSING AGREEMENT BETWEEN TWO METHODS OF CLINICAL MEASUREMENT , 1986, The Lancet.

[13]  P. Paré,et al.  Airway narrowing in excised canine lungs measured by high-resolution computed tomography. , 1992, Journal of applied physiology.

[14]  N. Müller,et al.  Hyperinflation in asthma and emphysema. Assessment by pulmonary function testing and computed tomography. , 1988, Chest.

[15]  R. Brown,et al.  Effect of lung inflation in vivo on airways with smooth muscle tone or edema. , 1997, Journal of applied physiology.

[16]  L. Boulet,et al.  Airway responsiveness and bronchial-wall thickness in asthma with or without fixed airflow obstruction. , 1995, American journal of respiratory and critical care medicine.

[17]  E. Weibel,et al.  Fixation of the lung by formalin steam in a controlled state of air inflation. , 2015, The American review of respiratory disease.

[18]  Comment on “Schottky contact and thermal stability of Ni on n-type GaN” [J. Appl. Phys. 80, 1623 (1996)] , 1997 .

[19]  N. Thomson,et al.  Computed tomographic scanning of the lung in patients with allergic bronchopulmonary aspergillosis and in asthmatic patients with a positive skin test to Aspergillus fumigatus. , 1994, Thorax.

[20]  E A Hoffman,et al.  Assessment of methacholine-induced airway constriction by ultrafast high-resolution computed tomography. , 1993, Journal of applied physiology.

[21]  E A Hoffman,et al.  Measurement of three-dimensional lung tree structures by using computed tomography. , 1995, Journal of applied physiology.

[22]  A A Bankier,et al.  Bronchial wall thickness: appropriate window settings for thin-section CT and radiologic-anatomic correlation. , 1996, Radiology.