Lung Cancer Screening CT assessment and management
1 Scan Information
Is this a new nodule?
2 Nodule Characteristics
Nodule Type
Average of long and short axis
For part-solid nodules only
Nodules with benign calcification patterns are classified as Category 2 regardless of size.
3 Suspicious Features (4X Modifier)
About Lung-RADS v2022
Lung-RADS (Lung Imaging Reporting and Data System) is a quality assurance tool developed by the American College of Radiology (ACR) to standardize lung cancer screening CT reporting and management recommendations.
Screening Eligibility (USPSTF 2021)
Age 50-80 years
≥20 pack-year smoking history
Current smoker OR quit within past 15 years
No symptoms of lung cancer
Lung-RADS Categories
Category
Description
Malignancy Risk
Management
1
Negative (no nodules)
<1%
Continue annual LDCT
2
Benign appearance/behavior
<1%
Continue annual LDCT
3
Probably benign
1-2%
6-month LDCT
4A
Suspicious
5-15%
3-month LDCT
4B
Very suspicious
>15%
Chest CT, PET-CT, tissue sampling
4X
Suspicious + additional features
Variable
As per 4A/4B + clinical correlation
Size Thresholds - Solid Nodules
Baseline Screening
Size
Category
<6 mm
2
6-8 mm
3
8-15 mm
4A
≥15 mm
4B
New Nodule on Follow-up
Size
Category
<4 mm
2
4-6 mm
3
6-8 mm
4A
≥8 mm
4B
Size Thresholds - Part-Solid Nodules
Total Size
Solid Component
Category
<6 mm
Any
2
≥6 mm
<6 mm
3
≥6 mm
6-8 mm
4A
≥6 mm
≥8 mm
4B
Size Thresholds - Ground-Glass Nodules
Scan Type
Category 2
Category 3
Baseline
<30 mm
≥30 mm
New nodule
<20 mm
≥20 mm
4X Modifier
The "X" modifier is added to category 3, 4A, or 4B when additional suspicious features are present:
Spiculation: Irregular margins with radiating linear strands
Lymphadenopathy: Enlarged or morphologically suspicious nodes
Growing nodule: Increase in size compared to prior imaging
Known malignancy: History of primary cancer (risk of metastasis)
Part-solid with growing solid component
Benign Calcification Patterns
Nodules with the following calcification patterns are classified as Category 2 regardless of size:
Complete (diffuse) calcification
Central calcification
Laminated (concentric) calcification
Popcorn calcification (hamartoma)
Fat-containing nodule (hamartoma)
Key Changes in Lung-RADS v2022
Adjusted size thresholds based on nodule volume
Clarified management for atypical adenomatous hyperplasia-like GGNs
Enhanced guidance for part-solid nodule assessment
Updated S modifier for incidental findings
References
American College of Radiology. Lung-RADS v2022 Assessment Categories. ACR; 2022. ACR Lung-RADS
Kazerooni EA, Armstrong MR, Amorosa JK, et al. ACR CT Accreditation Program and the Lung Cancer Screening Program Designation. J Am Coll Radiol. 2015;12(1):38-42. doi:10.1016/j.jacr.2014.08.016
McKee BJ, Regis SM, McKee AB, et al. Performance of ACR Lung-RADS in a Clinical CT Lung Screening Program. J Am Coll Radiol. 2016;13(2):R25-R29. doi:10.1016/j.jacr.2015.09.035
Pinsky PF, Gierada DS, Black W, et al. Performance of Lung-RADS in the National Lung Screening Trial. Ann Intern Med. 2015;162(7):485-491. doi:10.7326/M14-2086
US Preventive Services Task Force. Screening for Lung Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2021;325(10):962-970. doi:10.1001/jama.2021.1117