By Dr Scott Claxton
This post first appeared in Medical Forum (September 2020) and has been edited.
Key messages
- The lungs are exposed to challenges and assaults, which can leave their mark.
- With the growing use of cardiac CT, these findings will be more frequent.
- The specific nature of the findings will determine the need and extent of follow-up.
The increasing use of cardiac CT for diagnosing coronary artery disease and assessing cardiac risk has led to a rise in the incidental detection of non-cardiac abnormalities, particularly in the lungs. These incidental findings may also include abnormalities in the chest wall, breasts, skeleton, lung, pulmonary vasculature, mediastinum, and non-coronary vasculature, and can vary widely in their significance.
Classification of Incidental Lung Findings:
- Significant Findings:
- Lung Nodules and Masses: These are notable for further investigation, especially if they are larger than 3 cm or if the patient has a history of smoking. Smaller nodules, especially if ground-glass or semi-solid, may require follow-up CT scans based on established guidelines (such as those from the Fleischner Society).
- Pulmonary Emboli: Should be assessed promptly as they can indicate a serious underlying condition.
- Aortic Abnormalities, Breast Masses, Pleural Masses and Effusions: These findings typically necessitate further evaluation to determine their clinical significance.
- Less Immediately Significant Findings:
- Emphysematous Changes: These may reflect age-related changes or long-term exposure to irritants such as cigarette smoke or pollution.
- Small Nodules (<6mm): Often benign but may require follow-up depending on the patient’s risk factors.
- Pleural Thickening and Interstitial Lung Abnormalities: May be related to benign age-related changes or past exposures and generally require follow-up if symptomatic or if there is progression.
Management of Incidental Findings:
- Lung Nodules:
- Large Nodules/Masses: Typically require biopsy or further imaging to rule out malignancy, particularly in patients with a history of smoking or other risk factors.
- Small Nodules: Follow-up is usually guided by specific protocols, which balance the need for timely diagnosis with the avoidance of excessive radiation from repeated imaging.
- Other Pulmonary Findings:
- Bronchial Wall Thickening, Emphysema, and Fibrosis: Often related to age, environmental exposures, or previous smoking. Initial clinical assessment and possibly lung function testing may be necessary to evaluate these changes.
- Progression Monitoring: Follow-up intervals for conditions such as interstitial lung abnormalities may vary but typically do not need to be more frequent than annually unless symptoms develop or change is noted.
Follow-Up Considerations:
- Assessment Strategy: Determining the appropriate follow-up depends on the nature of the incidental finding and the patient’s overall risk profile. For significant findings, further diagnostic procedures or specialist referrals may be warranted.
- Historical Context: Previous imaging and a patient’s exposure history (e.g., occupational or environmental) are crucial in shaping the follow-up plan and understanding the context of incidental findings.
Conclusion:
As cardiac CTs become more prevalent, incidental pulmonary findings will increasingly be encountered. The management of these findings should be guided by their significance, the patient’s clinical history, and established follow-up protocols. The goal is to ensure appropriate evaluation and intervention while avoiding unnecessary procedures and minimizing patient anxiety.
