BACKGROUND: Long-term antifungal therapy is usually the only treatment option for chronic pulmonary aspergillosis. However, response rates are difficult to compare because the reported clinical, mycologic, or radiologic criteria are not standardized. Objective parameters are therefore needed. To define the most relevant CT imaging variables in assessment of response to treatment, we investigated changes over time in CT imaging variables. METHODS: Changes in CT imaging variables were assessed by systematic analysis of the CT scan findings of 36 patients at diagnosis and 6 months after initiation of treatment. The relevant radiologic variables were determined by selecting those showing significant changes over time. Two experienced thoracic radiologists, blinded for clinical and serologic response, independently performed CT scan analyses. Interreader agreement and concordance between radiologic and clinical response were evaluated. RESULTS: Of the 36 patients, seven experienced clinical deterioration while undergoing therapy. Significantly evolving radiologic variables included cavity and pleural wall thickening (P