Incidental Pulmonary Nodules Are Common on CT Coronary Angiogram and Have a Significant Cost Impact.

Background: Computed tomography (CT) coronary angiogram (CTCA) is commonly used for diagnostic evaluation of low-moderate risk patients due to its excellent performance and cost-effectiveness. However, previous cost analyses have not factored in the burden of management of pulmonary nodules, which are a common occurrence. We sought to describe the frequency and characteristics of lung nodules on CTCA in an Australian tertiary hospital, and to assess cost impacts.

Methods: Consecutive CTCAs performed in the calendar year 2012 were retrospectively identified from the imaging department database. Subjects were excluded if they were under the age of 35, had known malignancy or findings identified prior to CTCA. Patients were stratified on smoking history and nodule size.

Results: Of the 2479 CTCAs included, full-field imaging revealed nodules in 358 patients (13.9%). The nodules were generally small (73% <6mm), multiple (63%) and in the lower lobe (83.4%). There was no significant difference when stratified for smoking, with 60% of nodules detected in never-smokers. A minimum of 445 subsequent scans was required for nodule surveillance, resulting in an additional overall cost of $63.62 per CTCA. Limited-Field-of-View (L-FOV) would have identified only 22 nodules, with a cost of $6.14 for every CTCA performed, a cost saving of $57 per patient.

Conclusions: Indeterminate pulmonary nodules are a common incidental finding on CTCA and prevalence appears to be independent of smoking status. There is a consequent significant cost burden that has not previously been recognised. Use of L-FOV reduces the number of nodules identified, with a significant cost benefit, but this has to be balanced against the ethical and medico-legal issues inherent in not reconstructing the irradiated lung.