Assessment of regional contribution of different areas of the lung to its integrated function is often required, such as prior to lung resection in the presence of tumor or emphysema. This assessment is derived from the proportion of zonal radionuclear perfusion or ventilation. The investigators hypothesized that lung VRI may provide an alternative approach to assess regional lung function.

Patients diagnosed with moderate-to-severe COPD by lung function studies and clinical evaluation presented in stable clinical condition and were evaluated by lung sound recordings and quantitative V/Q lung scintigraphy. Regional signals (percentage of lung sounds) for left and right lungs were compared with the corresponding regional count percentages of each radionuclide scan, by V/Q scan regions of interest.

Inclusion Criteria:

• Patient is able to read and understand the Informed Consent Form and he/she will provide written Informed Consent.
• Male or female in the age range of 18-85 years.
• The patient will undergo V/Q scan (up to ONE WEEK from the VRI recording)
• The patient presented for evaluation of COPD.
• Body Mass Index >21.

Exclusion Criteria:

• Unstable clinical status such as fever, acute shortness of breath, cough, hemoptysis, cheat pain, or acute chest illness.

• Chest wall deformation;

• Spine deformation (including severe scoliosis);

• Hirsutism;

• Potentially contagious skin lesion on the back;

• Skin lesion that would interfere with sensor placement;

• Any additional chronic lung disease of any findings such as past tuberculosis, visualized on CXR.

  8. Previous resection lung surgery and history of lung tumor; 9. Cardiac pacemaker or implantable defibrillator

Males and females who were diagnosed with moderate-to-severe COPD by lung function studies and clinical evaluation