A modified method of lung tissue volume measurement using computed tomography numbers

Area of Science:

• Pulmonary imaging and quantitative analysis.
• Medical physics and biomedical engineering.

Background:

• Computed tomography (CT)-derived lung tissue volumes often exceed those from other methods.
• Accurate reference values for normal lung tissue volume are crucial for understanding lung diseases and assessing lung function and growth.

Purpose of the Study:

• To establish a precise method for calculating lung tissue volume utilizing CT numbers.
• To provide reliable reference values for normal lung tissue volume.

Main Methods:

• Developed an equation for lung tissue volume calculation based on volume and composition ratios, using defined CT numbers for air and lung tissue.
• Determined CT number definitions by measuring atelectasis areas and tracheal air.
• Evaluated measurement error in normal cases across multiple CT scans and breathing phases.
• Calculated lung tissue volume in 100 normal individuals (50 males, 50 females).

Main Results:

• Lung tissue volume demonstrated a moderate correlation with height (r=0.65) and a strong correlation with total lung volume (r=0.75).
• Estimated lung tissue volume was approximately 530 ml for a standard body size (1.7 m height).
• The developed method exhibited a variation of 1.7-17.4%.

Conclusions:

• The CT number-based measurement method aligns with previous non-image analysis findings.
• This noninvasive technique offers significant potential for generating novel anatomical lung information.