Unlocking the Power of Incidental Lung Cancer Screening CT Findings
New review offers guidance for recognizing, reporting and managing incidental findings
In concert with the RadioGraphics monograph, RSNA News shares the latest on the role of medical imaging in disease screening.
Low-dose lung cancer screening (LCS) CT scans can reveal many findings beyond lung nodules, including coronary artery calcification, emphysema, osteoporosis, thoracic aortic aneurysms and upper abdominal lesions.
Recognizing these incidental findings is only the first step; the challenge for radiologists is to determine which findings warrant reporting, follow-up and intervention.
“There’s sometimes a perception that incidental findings are primarily a burden or source of unnecessary downstream testing,” said Suzanne Byrne, MD, thoracic radiologist and director of the Lung Cancer Screening Program at Mass General Brigham. “That concern can be valid if findings are overcalled or managed inappropriately. However, in general, lung cancer screening CT offers a unique opportunity to identify clinically important findings in a high-risk population.”
Dr. Byrne co-authored a RadioGraphics article providing an evidence-based framework for identifying, reporting and managing incidental findings on LCS CT.
“Consistent implementation of guidance for incidental findings in lung cancer screening CT is hindered by variability in radiology reporting, differences among clinical guidelines, limited clinician awareness and inadequate systems for tracking follow-up,” said Dr. Byrne, who is also an assistant professor of radiology at Harvard Medical School. “These challenges can lead to both unnecessary investigations and missed clinically significant findings. Overcoming them requires standardized reporting templates, harmonized evidence-based guidelines, integrated clinical decision support, multidisciplinary collaboration, effective patient communication and electronic tracking systems to ensure appropriate and timely follow-up.”
From Incidental to Actionable Finding
About one-third of low-dose LCS CTs in the National Lung Screening Trial (NLST) revealed incidental abnormalities. While the review addresses a broad range of findings, Dr. Byrne said some of the most valuable findings are those that identify subclinical disease.
Emphysema is a prime example. CT-detected emphysema is associated with all-cause, cardiovascular and COPD mortality, even in patients with normal spirometry. In the NLST population, approximately 31% of patients had emphysema. More than 80% were previously undiagnosed.
AI-based quantification tools can aid in rapid, standardized reporting. Identifying and effectively communicating these findings presents an opportunity to prompt smoking cessation, clinical assessment and timely intervention with new and emerging therapies.
“Radiologists can improve the detection and management of emphysema during lung cancer screening by consistently assessing and reporting its presence using standardized reporting templates and severity classifications,” Dr. Byrne said. “Incorporating emphysema assessment into LCS CT interpretation, alongside structured recommendations for smoking cessation, pulmonary function testing and/or referral to pulmonology when needed, can help ensure findings are acted upon.”
Incidental finding of an ascending thoracic aortic aneurysm detected at lung cancer screening CT. (A) Axial CT image shows dilatation of the ascending aorta measuring up to 4.7 cm in transverse dimension (yellow line). (B) Sagittal CT image shows dilatation of the ascending aorta measuring up to 4.7 cm in the anteroposterior dimension (yellow line).
https://doi.org/10.1148/rg.260012 ©RSNA 2026
Interstitial lung abnormalities (ILAs) present another opportunity for early identification and intervention. They have been detected on about 4% to 17% of LCS CT exams, with more than half progressing on serial imaging. Still, ILAs are underreported and often underemphasized, which results in diagnostic and referral delays, the authors noted.
Both the American Thoracic Society and Fleischner Society emphasize recognition and documentation of ILAs on LCS CT. Once an ILA has been identified, the authors recommend baseline assessment of symptoms, risk factors and pulmonary function, along with risk-reduction measures such as smoking cessation. Risk varies by pattern, with subpleural fibrotic ILA being the most likely to progress. Patients can be stratified into lower- or higher-risk surveillance.
Coronary artery calcium (CAC) is also common in populations undergoing lung cancer screening. Although multiple societies have recommended reporting CAC on noncardiac exams for more than a decade, it remains underreported.
Routine LCS CT allows for opportunistic CAC scoring without additional cost or radiation exposure. The authors recommend documenting CAC in the impression section of reports, not simply the narrative section, and providing clear follow-up guidance. Dr. Byrne and colleagues note that using AI to automate CAC scoring has demonstrated good reliability compared with manual methods and can save time.
Beyond the Chest
Dr. Byrne and colleagues also highlight several important extrapulmonary findings that can benefit from early detection and structured follow-up.
Osteoporosis is one example. The condition affects an estimated 10 million adults, a figure that is expected to rise. Less than half of eligible individuals receive recommended screening with dual X-ray absorptiometry (DXA), and many suffer fractures before they are diagnosed.
LCS CT provides an opportunity to evaluate vertebral trabecular bone attenuation as an indicator of osteoporosis, according to Dr. Byrne and colleagues. DXA is recommended when the value is less than 100 Hounsfield units at the L1 vertebra, though documentation of vertebral body compression fractures may help establish a diagnosis without further testing.
Opportunistic identification of abdominal lesions in the liver, adrenal glands and kidneys is common. Although algorithms and guidelines exist to guide management of these findings, adherence among clinicians is suboptimal, the authors noted.
Incidental pancreatic lesions are less common, but appropriate follow-up is especially important given the poor prognosis associated with pancreatic cancer.
Focusing on Findings That Matter
Dr. Byrne noted that the goal isn’t to pursue every incidental finding; it’s to consistently identify, report and apply evidence-based management to improve patient outcomes.
“Structured reporting promotes consistency, prioritizes actionable findings and provides management recommendations when appropriate,” Dr. Byrne said. “Rather than reporting every incidental abnormality with equal emphasis, structured reports allow radiologists to distinguish findings that warrant follow-up from those that do not. This approach reduces ambiguity for referring clinicians, minimizes unnecessary investigations and patient anxiety, and helps ensure that important incidental findings receive appropriate attention.”
With emerging applications across many incidental findings, AI has the potential to further enhance and scale lung cancer screening beyond pulmonary nodules.
“Lung cancer screening CTs should be viewed as an opportunity to improve patient health beyond lung cancer detection alone,” Dr. Byrne emphasized. “By identifying and acting on these incidental findings, radiologists can enable earlier intervention and potentially improve overall health outcomes in a population at high risk for multiple chronic diseases.”
For More Information
Access the RadioGraphics article, “Lung Cancer Screening: Beyond Pulmonary Nodules,” and the invited commentary, “Measured, Not Yet Managed: Moving Toward Comprehensive Lung Screening.”
Read previous RSNA News stories on lung cancer screening: