RSNA 2017: Fleischner Society Guidelines for Incidental Nodule Management

By Staff News Brief

In 2005, the Fleischner Society Guidelines for management of incidentally detected solid pulmonary nodules were published and have become the established gold standard. This year the guidelines were updated to expand the flexibility for clinicians and patients in clinical decision making and to individualize the management of detected lesions. Cardiothoracic radiologists at the University of Chicago Medicine summarize and explain these changes in a RSNA poster presentation (CH118-ED-X).

The Fleischner Society Guidelines are designed for the management of incidental solid nodules, defined as those which have homogeneous soft tissue attenuation, in the general population. Patients under the age of 35 years who are immunocompromised or have a known malignancy require individualized management. Physicians should follow Lung-RADS guidance for nodules identified by lung cancer screening.

Guidelines for nodule management are based on individual risk assessment using the categories of the American College of Chest Physicians (ACCP). Patients who have a greater than 65% risk of malignancy are 55+ years old, have a family history of lung cancer and/or a history of heavy smoking, larger nodule size, in an upper lobe location, and irregular or spiculated nodule margins. Size and morphology are the most dominant risk determinants.

The guidelines have not changed with respect to either solid solitary or multiple nodules less than 6 mm. No routine follow-up is needed for low risk patients, and a computed tomography (CT) exam is optional at 12 months. The authors cited lobulated margins in a small solid lesion and upper lobe lesions with suspicious morphology as two examples when a 12-month follow-up CT scan may be warranted.

For both the 2005 and 2017 guidelines for low- and high-risk patients with a single, a 6-8 mm nodule a follow-up CT scan should be performed at 6-12 months. However, 2017 guidelines recommend a follow-up CT at 18-24 months, whereas this was optional in the 2005 guidelines. For nodules larger than 8 mm, both sets of guidelines recommend CT, PET/CT or tissue sampling at 3 months. The revised guidelines reflect supporting data from lung cancer screening trials.

Patients with multiple nodules  6 mm or greater in size that are categorized both as low- and high-risk should have a follow up CT scan at 3-6 months in both the 2005 and 2017 guidelines. However, a follow-up CT scan should be performed between 18-24 months, a change from the 2005 guidelines in which this follow-up scan is optional and left to the discretion of the clinician.

The guidelines also specify the technical parameters to accurately measure and characterize pulmonary nodules. Imaging criteria includes acquisition of thin sections 1-1.5 mm, acquisition of off-axis images (sagittal and coronal) to help distinguish nodules from scars, and use of a low dose CT protocol (CTDIvol) max 3mGy). Nodules less than 3 mm should be designated as “micronodules”.

Juliana Bueno, MD, a radiologist in the Cardiothoracic Imaging section of the Department of Radiology, and colleagues emphasize the need for the measurement of a pulmonary nodule to be accurate, because this data defines the baseline risk for malignancy, allows the detection of change in size on follow-up CTs, and can also allow allocation of patients in management algorithms.

Measurements, rounded to the nearest whole mm, should be performed in the lung windows, ideally using the thinnest sections less than 1.5 mm and using a high spatial frequency filter. Solid nodules less than 10 mm should be expressed as the average between the maximal long axis and the perpendicular maximal long axis in the same plane. Those larger than 10 mm and masses should have dimensions recorded in both long and short axis measurements.

The authors also noted that the diagnostic considerations in patients with multiple nodules are different than for patients with single nodules. The nodule considered to be most suspicious should be used to determine management, following the guidelines for solitary nodule. When nodules are basal and peripheral in distribution, metastasis are the leading consideration. In the majority of cases, if a nodule is a metastatic lesion, it will show growth within three months.

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RSNA 2017: Fleischner Society Guidelines for Incidental Nodule Management.  Appl Radiol. 

By Staff News Brief| November 28, 2017

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