Practice of Medicine


Updated Guidelines for Management of Pulmonary Nodules Found Incidentally on CT

By: Marshaleen King, MD

The Fleischner Society has published new guidelines for the management of incidental pulmonary nodules detected on CT images. The updated guidelines reflect new data in the field and are based on the consensus of a multidisciplinary group comprised of experienced thoracic radiologists, pulmonologists, surgeons, pathologists and other specialists. The guidelines apply to incidental nodules found in adults ≥ 35 years and should not be used in persons < 35, patients at risk for infection due to an immunocompromised state, individuals being screened for lung cancer or people with a known history of a primary cancer.

Significant changes to the previous Fleischner guidelines include an increase in the minimum size of solid nodules that warrant routine follow-up (minimum threshold now 6mm instead of 4mm). In addition, fewer follow-up CTs are recommended for solid nodules that have remained stable in size. In the case of sub-solid nodules, the total duration of follow-up recommended has been increased to 5 years.

The new recommendations are geared toward reducing unnecessary follow-up CT scans that expose patients to unwarranted doses of radiation. The guidelines indicate that no routine follow-up is needed for nodules < 6 mm in low risk patients unless there are multiple nodules that are sub-solid in appearance. Utilization of a low-radiation technique is recommended when chest CTs are performed for the follow-up of lung nodules to limit radiation exposure.

In a number of scenarios, the new guidelines include a range of times for performing follow-up CT based on individual patient factors in place of the previously fixed time intervals. Factors that have to be taken into consideration when determining the follow-up intervals for individual patients include the appearance of their nodule, (spiculated margins indicate a higher cancer risk), the location of their nodule, (upper lobe nodules portend a higher cancer risk), their smoking history, and their personal preference regarding aggressive versus conservative management.

Given the importance of taking the appearance of a lung nodule into consideration when making decisions regarding follow-up, it is recommended that adults get “thin section” (typically 1.0 mm cuts) chest CTs since thick section chest CTs make it more difficult to accurately characterize small nodules.

MacMahon H, Naidich DP, Goo JM, Lee KS, et. al. Guidelines for Management of Incidental Pulmonary Nodules Detected on CT Images: From the Fleischner Society 2017. Radiology. 2017 Jul;284(1):228-243. doi: 10.1148/radiol.2017161659. Epub 2017 Feb 23.



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