What are the Lung‑RADS categories and the recommended follow‑up or management for each category?

Lung-RADS Categories and Management

Lung-RADS classifies lung screening findings into categories 1-4 (plus S for significant non-nodule findings), with categories 1-2 considered negative requiring annual screening, category 3 requiring 6-month follow-up CT, and category 4 requiring multidisciplinary team evaluation for further diagnostic workup. 1

Category Definitions and Management

Lung-RADS 1 or 2: Negative Screening

• No actionable lung nodules detected 1
• Management: Return to annual screening (RTAS) 1, 2
• Communication via text message to patient and electronic medical records to primary care physician 1
• Next screening round automatically scheduled 1
• Category 2 includes:
  • Solid nodules < 6 mm 2
  • Ground-glass nodules < 30 mm (updated in Lung-RADS 1.1) 2, 3
  • Perifissural nodules < 10 mm 2, 3

Lung-RADS 3: Probably Benign

• Probability of malignancy: 1-2% 2
• Includes:
  • Solid nodules 6 mm to < 8 mm in diameter 2
  • Part-solid nodules with solid component < 6 mm 2
  • New solid nodules 4 to < 6 mm 2
  • Ground-glass nodules > 30 mm or new 2
• Management: Repeat CT scan at 6 months 1, 2
• If nodule size does not increase on subsequent CT, reintegrate into regular annual screening program 1
• If suspicious findings or growth detected, escalate management to Lung-RADS 4 protocol 1
• Prompt referral to specialized pulmonology consultation 1

Lung-RADS 4: Suspicious

• Subdivided into 4A, 4B, and 4X based on suspicion level 2, 4
• Category 4A includes:
  • Solid nodules 8-15 mm requiring 3-month follow-up 2
  • Part-solid nodules with solid component 6-8 mm 2
• Category 4B includes:
  • Solid nodules ≥ 15 mm 2
  • Part-solid nodules with solid component > 8 mm 2
  • New or growing nodules meeting size criteria 2
• Management: Immediate referral to Multidisciplinary Team 1
• Team composition: Pulmonologists, Radiologists, Interventional Radiologists, and Thoracic Surgeons 1
• Team determines appropriate diagnostic strategy and establishes follow-up plan 1
• Diagnostic options include transthoracic biopsy, bronchoscopy with EBUS, or combined approaches 1

Lung-RADS S: Significant Non-Nodule Findings

• Other clinically significant findings requiring attention 1
• Examples include coronary artery calcification, thyroid nodules, adrenal nodules, thoracic aortic aneurysms, pleural effusions 5
• Communication via text message to patient and electronic medical records to primary care physician 1
• Requires standardized description and clear communication about responsibility for follow-up 5

Key Clinical Considerations

Screening Interval

• Standard interval between screening rounds: 1 year for negative results 1
• This interval should be re-evaluated based on emerging evidence 1

Important Caveats

• Solid nodules < 8 mm typically have probability of malignancy < 2% 2
• Transthoracic pulmonary biopsy has high diagnostic yield but carries 25.9% pooled incidence of pneumothorax and 6.9% chest drain insertion rate 1
• Pure ground-glass nodules have relatively high prevalence of premalignant or malignant disease but uncertain prognosis 6
• PET scanning has limited sensitivity (47-62%) for lepidic-predominant adenocarcinomas often associated with subsolid nodules 6

Structured Reporting

• Programs should use standardized reporting systems (ACR Lung-RADS is most prevalent) 5
• Reports should include number, location, size, characteristics of nodules and guideline-based surveillance recommendations 5