LUNG-RADSLung CT Screening Classification (v2022)
Radiologic Assessment
Screening Note
The 2022 update includes modifications to nodule size thresholds and emphasizes the importance of nodule growth rate and morphology (e.g., spiculation).
Screening Outcome
Category 1
Management Outlook
Negative. No nodules or nodules with definitely benign features. Continue annual screening.
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
When to Use
Exclusively for asymptomatic patients undergoing routine lung cancer screening with Low-Dose CT (LDCT).
Patients typically meet USPSTF criteria: age 50-80 years, ≥ 20 pack-year smoking history, currently smoking or quit within the past 15 years.
NOT to be used for patients presenting with symptoms (e.g., hemoptysis) or for incidental nodules found on standard CT (use Fleischner guidelines instead).
How it Works
Classification Framework
| Category | Nodule Features (Solid) | Risk of Malignancy |
|---|---|---|
| 1 (Negative) | No nodules, or nodules < 6 mm (or < 113 mm³) | < 1% |
| 2 (Benign Appearance) | Benign calcification pattern (popcorn, concentric), or solid nodules < 6 mm | < 1% |
| 3 (Probably Benign) | Solid nodules ≥ 6 to < 8 mm at baseline, or new nodule < 6 mm | 1 - 2% |
| 4A (Suspicious) | Solid nodules ≥ 8 to < 15 mm at baseline, or growing nodule < 8 mm, or new nodule 6 to < 8 mm | 5 - 15% |
| 4B (Very Suspicious) | Solid nodules ≥ 15 mm, or new or growing nodule ≥ 8 mm | > 15% |
| 4X | Category 3 or 4 findings with additional malignant imaging features (e.g., spiculation, GGN doubling) | > 15% |
Clinical Pearls
Actionable Management
Categories 1 and 2 require standard annual LDCT follow-up. This aggressively cuts down on unnecessary biopsies.
Category 3 mandates a 6-month follow-up LDCT to establish stability or growth.
Category 4A usually prompts a 3-month LDCT. PET-CT is considered if the solid component is ≥ 8 mm.
Category 4B or 4X demands immediate diagnostic workup (PET-CT, tissue sampling via bronchoscopy/TTNA, or surgical resection).
The 2022 Volume Update
Volumetry is now heavily emphasized over linear diameter. Because lung nodules grow in three dimensions, a 26% increase in volume (which constitutes growth) often corresponds to only a 2 mm increase in diameter, which is near the limits of manual measurement reliability.
The Evidence
Key Reference
Lung-RADS Version 2022 Assessment Categories
American College of Radiology • ACR.org. 2022;Clinical Standard
Last Comprehensive Review: 2026