Coronary computed tomographic angiography and incidental pulmonary nodules.

I ncidental findings are an important topic in diagnostic imaging. Because of the comprehensive nature of computed tomography (CT) scanning, incidental findings are seemingly found on almost every CT scan performed for a wide variety of reasons in a radiology department. Many of these incidental findings such as a liver cyst are benign and immediately dismissed. Other findings require more extensive interpretation and management. In regard to coronary CT angiography (CCTA), a similar problem exists. Even though we have a primary interest in the heart, the CT scanner delivers radiation to all tissues of the chest such as the bones, lung parenchyma, and breast tissue. Extracardiac findings are reported to occur in 15% to 67% of CCTA examinations, 1 and the vast majority (≈80%) represent pulmonary nodules. For diagnostic radiologists, evaluation of all tissues in the x-ray path has long been the standard of care. If an x-ray of the shoulder includes the lateral lung fields, the diagnostic radiologist evaluates that portion of the lung for an infiltrate or lung mass. Similarly, for CT scanning, if the primary request is to evaluate for pulmonary embolus (pulmonary arteries) or lymphadenopa-thy (mediastinum), we also expect the radiologist to evaluate all tissues that are exposed to the x-ray beam, including the lungs. Cardiologists who interpret CCTA examinations may not have training that allows diagnostic evaluation of all tissues within the field of view of the x-ray beam. This results in 2 different strategies to deal with extracardiac tissues beyond the coronary arteries: 1. The CCTA images can undergo a separate evaluation by a radiologist for interpretation of extracardiac tissues. This approach requires additional time and effort that may not be fully reimbursed. Some office-based practices may not have radiology expertise available. A potential solution is to acquire sufficient training to allow confident handling of such findings. 2. Tissues beyond the heart can be (mostly) removed in an automatic manner by the CT scanner software (Figure). Noncardiac data may be digitally discarded. This digital deletion approach is only partially successful because some lung tissue invariably remains in the field of view. According to an expert consensus statement, 1 the digital deletion approach reduced the number of incidental non-coronary findings from 20% to 2%. The justifications for option 1 or 2 tend to be along medical or ethical lines of reasoning. For example, medically, there may be no clinical indication to look at the lungs …