CT Indexes of Emphysema and Airways in Healthy Volunteers: Normal Values; Relations With Gender, Height and Weight

Study Overview
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Brief Summary
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Various indexes have been proposed to quantify both pulmonary emphysema and airways disease on chest CT scans. It is unknown whether these indexes should be consider in absolute values or as compared to predicted normal values. The purposes of the present study is thus : a) to measure these indexes at CT in healthy volunteers; b) to investigate their relations with gender, height and weight.

Detailed Description
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87 healthy volunteers performed consecutively a low-dose chest CT scan and pulmonary function tests: On chest CT scans, indexes reflecting pulmonary emphysema and airways measurements have been computed by using dedicated softwares. Each of our three readers performed two reading sessions. Relative area of lung parenchyma with attenuation value less than -960 Hounsfield Units; luminal area and wall thickness in third and fourth generations airways were recorded. Pulmonary function tests were performed: vital capacity, forced vital capacity , functional residual capacity, total lung capacity, residual volume, forced expiratory volume in one second, and diffusion lung capacity for carbon monoxide were recorded (either in absolute values and percentage of predicted values). CT indexes were compared with gender, height and weight.

Official Title
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CT Indexes of Emphysema and Airways in Healthy Volunteers: Normal Values; Relations With Gender, Height and Weight

Conditions
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Healthy

Intervention / Treatment
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* Radiation: Low-dose chest CT scans


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Never smoked. No respiratory infection in the 4 weeks before the begin of the study. No history of pulmonary resection. No active malignancy or malignancy of any organ system within the past 5 years. Exclusion Criteria: no exclusion criteria

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Healthy Volunteers<br>Inclusion criteria: Aged 18 or more. Never smoked. No respiratory infection in the 4 weeks before the begin of the study. No history of pulmonary resection. No active malignancy or malignancy of any organ system within the past 5 years. | Radiation: Low-dose chest CT scans<br>* Supine chest CT scan after full inspiration. Acquisition parameters: (Topogram 35 mA 120 kV 512 mm length) 35 quality ref mAs with care-dose ON 120 kV Pitch 1.4 Rotation time 0.33 s Acquired images 64 x 0.6 mm<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| CT index - RA960 (%) | From acquired data, images were reconstructed using a soft algorithm. On these soft images, the relative area of lung parenchyma with attenuation value less than -960 Hounsfield Units was computed (expressed in %), as an index representative of pulmonary emphysema extent. | 4 hours | 
| CT index - LA3rd (mm2) | From acquired data, images were reconstructed using a high resolution algorithm. On these high-resolution images, the airway lumen was measured in third generations of airways (expressed in mm2). | 4 hours | 
| CT index - LA4th (mm2) | From acquired data, images were reconstructed using a high resolution algorithm. On these high-resolution images, the airway lumen was measured in fourth generations of airways (expressed in mm2). | 4 hours | 
| CT index - WT3rd (mm) | From acquired data, images were reconstructed using a high resolution algorithm. On these high-resolution images, the airway wall was measured in third generations of airways (expressed in mm). | 4 hours | 
| CT index - WT4th (mm) | From acquired data, images were reconstructed using a high resolution algorithm. On these high-resolution images, the airway wall was measured in fourth generations of airways (expressed in mm). | 4 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pulmonary function tests - VC (l) | Vital capacity was measured (expressed in l). | 4 hours | 
| Pulmonary function tests - FVC (l) | Forced vital capacity was measured (expressed in l). | 4 hours | 
| Pulmonary function tests - FRC (l) | Functional residual capacity capacity was measured (expressed in l). | 4 hours | 
| Pulmonary function tests - TLC (l) | Total lung capacity was measured (expressed in l). | 4 hours | 
| Pulmonary function tests - RV (l) | Residual volume was measured (expressed in l). | 4 hours | 
| Pulmonary function tests - FEV1 (l) | Forced expiratory volume in one second was measured (expressed in l). | 4 hours | 
| Pulmonary function tests - DLCO (ml/min/ mmHg) | Diffusion lung capacity for carbon monoxide was measured (expressed in ml/min/ mmHg) | 4 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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emphysema, airway remodelling, multidetector computed tomography