Lung-RADS
Lung-RADSTM (or lung imaging reporting and data system) is a classification proposed to aid with findings in low-dose CT screening exams for lung cancer. The goal of the classification system is to standardize follow-up and management decisions. The system is similar to the Fleischner criteria but designed for the subset of patients intended for low-dose screening studies.
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Classification system
Category 0 (incomplete)
- prior CT studies were performed, but are not available for comparison
- lungs are incompletely imaged
Category 1 (negative, <1% chance of malignancy)
- no lung nodules
- lung nodule(s) with specific findings favoring benign nodule(s)
- complete calcification
- central calcification
- popcorn calcification
- calcification in concentric rings
- fat-containing nodules
Category 2 (benign appearance, <1% chance of malignancy)
- solid nodule(s)
- <6 mm at baseline
- new nodule <4 mm
- subsolid nodule(s)
- <6 mm on baseline screening
- ground glass nodule(s)
- <30 mm (Version 1.1 change previously 20 mm)
- ≥30 mm and unchanged or slowly growing (Version 1.1 change previously 20 mm)
- category 3 or 4 nodules that are unchanged for ≥3 months
Category 3 (probably benign, 1-2% chance of malignancy)
- solid nodule(s)
- ≥6 mm to <8 mm at baseline
- new nodule 4 mm to <6 mm
- subsolid nodule(s)
- ≥6 mm total diameter with solid component <6 mm
- new <6 mm total diameter
- ground glass nodule(s)
- ≥30 mm on baseline CT or new (Version 1.1 change previously 20 mm)
Category 4A ( Probably suspicious, 5-15% chance of malignancy) (Version 1.1 change previously suspicious)
- solid nodule(s)
- ≥8 mm to <15 mm at baseline
- growing nodule(s) <8 mm
- new nodule 6 mm to <8 mm
- subsolid nodule(s)
- ≥6 mm total diameter with solid component ≥6 mm to <8 mm
- new or growing <4 mm solid component
- endobronchial nodule
Category 4B (suspicious, >15% chance of malignancy)
- solid nodule(s)
- ≥ 15 mm at baseline
- new or growing, and ≥8 mm
- subsolid nodule(s)
- solid component ≥8 mm
- new or growing ≥4 mm solid component
- For new large nodules that develop on an annual repeat screening CT, a 1 month LDCT may be recommended to address potentially infectious or inflammatory conditions. (Version 1.1 addition)
Category 4X (suspicious, >15% chance of malignancy)
- category 3 or 4 nodules with additional features or imaging findings that increase the suspicion of malignancy
- includes:
- spiculation
- ground glass nodule(s) that double in size in 1 year
- enlarged regional lymph nodes
- For new large nodules that develop on an annual repeat screening CT, a 1 month LDCT may be recommended to address potentially infectious or inflammatory conditions. (Version 1.1 addition)
Modified categories
- [X]S (e.g. "3S") if there is a clinically significant or potentially significant non-lung cancer finding
- (Version 1.1 REMOVAL): [X]C (e.g. "3C") for a patient with a prior diagnosis of lung cancer who returns to screening
Recommended follow-up
Category 0:
- comparison with prior studies before assignment of Lung-RADS classification
Category 1:
- continue annual screening with LDCT
Category 2:
- continue annual screening with LDCT
Category 3:
- 6-month follow-up with LDCT
Category 4A:
- 3-month follow-up with LDCT
- PET/CT may be used if there is a ≥8 mm solid component
Category 4B and 4X:
- chest CT with or without contrast, as appropriate
- PET-CT and/or tissue sampling depending on the probability of malignancy and comorbidities (PET-CT if solid component ≥8 mm)
- For new large nodules that develop on an annual repeat screening CT, a 1 month LDCT may be recommended to address potentially infectious or inflammatory conditions. (Version 1.1 addition)
Practical points
- nodule measurement should be in lung windows
- To calculate nodule mean diameter, measure both the long and short axis to one decimal point, and report mean nodule diameter to one decimal point. [previously recommended rounding to nearest whole number version 1.0.]
- only a single measurement is necessary for round nodules
- "growth" is an increase in size of ≥1.5 mm
- assignment of a Lung-RADS status is based on the most suspicious nodule
- category 4B management is based on multiple factors including overall patient status and patient preference
- Solid nodules with smooth margins, an oval, lentiform or triangular shape, and maximum diameter less than 10 mm (perifissural nodules) should be classified as category 2. (Version 1.1 addition)
See also
Related Radiopaedia articles
Chest
- imaging techniques
-
chest x-ray
-
approach
- adult
- pediatric
- neonatal
-
airspace opacification
- differential diagnoses of airspace opacification
- lobar consolidation
-
atelectasis
- mechanism-based
- morphology-based
- lobar lung collapse
- chest x-ray in the exam setting
- cardiomediastinal contour
- chest radiograph zones
- tracheal air column
- fissures
- normal chest x-ray appearance of the diaphragm
- nipple shadow
-
lines and stripes
- anterior junction line
- posterior junction line
- right paratracheal stripe
- left paratracheal stripe
- posterior tracheal stripe/tracheo-esophageal stripe
- posterior wall of bronchus intermedius
- right paraspinal line
- left paraspinal line
- aortic-pulmonary stripe
- aortopulmonary window
- azygo-esophageal recess
- spaces
- signs
- air bronchogram
- big rib sign
- Chang sign
- Chen sign
- coin lesion
- continuous diaphragm sign
- dense hilum sign
- double contour sign
- egg-on-a-string sign
- extrapleural sign
- finger in glove sign
- flat waist sign
- Fleischner sign
- ginkgo leaf sign
- Golden S sign
- Hampton hump
- haystack sign
- hilum convergence sign
- hilum overlay sign
- Hoffman-Rigler sign
- holly leaf sign
- incomplete border sign
- juxtaphrenic peak sign
- Kirklin sign
- medial stripe sign
- melting ice cube sign
- more black sign
- Naclerio V sign
- Palla sign
- pericardial fat tag sign
- Shmoo sign
- silhouette sign
- snowman sign
- spinnaker sign
- steeple sign
- straight left heart border sign
- third mogul sign
- tram-track sign
- walking man sign
- water bottle sign
- wave sign
- Westermark sign
-
approach
- HRCT
-
chest x-ray
- airways
- bronchitis
- small airways disease
-
bronchiectasis
- broncho-arterial ratio
- related conditions
- differentials by distribution
- narrowing
-
tracheal stenosis
- diffuse tracheal narrowing (differential)
-
bronchial stenosis
- diffuse airway narrowing (differential)
-
tracheal stenosis
- diverticula
- pulmonary edema
-
interstitial lung disease (ILD)
- drug-induced interstitial lung disease
-
hypersensitivity pneumonitis
- acute hypersensitivity pneumonitis
- subacute hypersensitivity pneumonitis
- chronic hypersensitivity pneumonitis
- etiology
- bird fancier's lung: pigeon fancier's lung
- farmer's lung
- cheese workers' lung
- bagassosis
- mushroom worker’s lung
- malt worker’s lung
- maple bark disease
- hot tub lung
- wine maker’s lung
- woodsman’s disease
- thatched roof lung
- tobacco grower’s lung
- potato riddler’s lung
- summer-type pneumonitis
- dry rot lung
- machine operator’s lung
- humidifier lung
- shower curtain disease
- furrier’s lung
- miller’s lung
- lycoperdonosis
- saxophone lung
-
idiopathic interstitial pneumonia (mnemonic)
- acute interstitial pneumonia (AIP)
- cryptogenic organizing pneumonia (COP)
- desquamative interstitial pneumonia (DIP)
- non-specific interstitial pneumonia (NSIP)
- idiopathic pleuroparenchymal fibroelastosis
- lymphoid interstitial pneumonia (LIP)
- respiratory bronchiolitis–associated interstitial lung disease (RB-ILD)
- usual interstitial pneumonia / idiopathic pulmonary fibrosis (UIP/IPF)
-
pneumoconioses
- fibrotic
- non-fibrotic
-
lung cancer
-
non-small-cell lung cancer
-
adenocarcinoma
- pre-invasive tumors
- minimally invasive tumors
- invasive tumors
- variants of invasive carcinoma
- described imaging features
- adenosquamous carcinoma
- large cell carcinoma
- primary sarcomatoid carcinoma of the lung
- squamous cell carcinoma
- salivary gland-type tumors
-
adenocarcinoma
- pulmonary neuroendocrine tumors
- preinvasive lesions
-
lung cancer invasion patterns
- tumor spread through air spaces (STAS)
- presence of non-lepidic patterns such as acinar, papillary, solid, or micropapillary
- myofibroblastic stroma associated with invasive tumor cells
- pleural invasion
- vascular invasion
- tumors by location
- benign neoplasms
- pulmonary metastases
- lung cancer screening
- lung cancer staging
-
non-small-cell lung cancer