Research to Evaluate a Possible Relation Between Values Obtained After Processing CT Images, Lung Function Tests and the Experience of the Patient During an Exacerbation in COPD Patients.

Inclusion Criteria: * Male or female, ≥ 40 years old * COPD as defined by the global Initiative on obstructive lung disease4 * Post-bronchodilator FEV1/FVC \< 70% AND post-bronchodilator FEV1 \<80%pred as documented in the last 5 years. * Smoking history of at least 10 pack-years * At entry in the study experiencing an exacerbation defined as an acute change in the patient 's baseline dyspnea, cough, and/or sputum that is beyond normal day to day variations, and that necessitates the administration or doubling of systemic corticosteroid treatment. * Patients must be able to understand and complete protocol requirements, instructions, questionnaires and protocol-stated restrictions. * Written and signed informed consent Exclusion Criteria: * Pregnant or lactating females * Patient diagnosed with asthma * Patient with pneumonia as defined radiologically at the start of the exacerbation * Patient with a history of or presence of lung cancer * Patient with an indication for non-invasive ventilation * Patient unlikely to comply with the protocol or unable to understand the nature, scope and possible consequences of the study. * Patient who received any investigational new drug within the last 4 weeks prior to visit 1.