Cardiac CT and pulmonary nodules; incidental findings and incidence of malignancy in an Australian population.

Background: CT Coronary Angiography provides accurate noninvasive evaluation of coronary arteries but also images lung parenchyma and other mediastinal structures. Little is known about the range and incidence of non-cardiac findings in the Australian population and while CT screening has been shown to reduce mortality in high risk individuals the significance of identified pulmonary nodules in this mixed risk population is unknown. A lack of data regarding the malignant potential of these incidentally identified nodules makes evaluation of the relative risk/benefit of both initial imaging of the lung and subsequent surveillance scanning is difficult. Method(s): A retrospective analysis was performed on reports of all cardiac CT scans done in the calendar year 2012. Descriptive data was collected including baseline patient characteristics, type of nodule and smoking history, as well as whether a full field or restricted field view was performed. Surveillance radiological data and pathology was collected on a sub-group of the population. Result(s): 2500 Cardiac CT scans analysed with 48% females. Reports analysed for presence of lung nodules and type of nodule with most common nodule granuloma. Total lung nodules 14% (355) with follow up recommended by specialist radiologists; significant variation from recommendation in practice was noted. 39% of population positive for smoking exposure placing them in high risk population. No episodes of malignancy within follow up CT scans with the majority of nodules being stable over the follow up period. Majority of nodules were <4mm making up 60% of the total nodules described, 4-8mm 20% nodules of described nodules, >8mm making up 12% of nodules. Pulmonary Cysts represented 4% of nodules. Subpleural nodules described separately and making up a minority of nodules. Conclusion(s): Cardiac CTs are an increasingly common modality used to evaluate coronary artery disease. Pulmonary nodules are a common finding with a prevalence in