The Lung Reporting and Data System

LU-RADS is a Canadian-designed classification system for CT lung cancer screening. The 6-level system moves beyond simple negative/positive reporting schemes and is linked directly to suggested follow-up pathways.

Improving communication

LU-RADS is designed to improve communication with patients and clinicians, provide a data collection framework, and assist with radiologist training and quality assurance.




1 No nodule


Return to regular screening.

Risk of malignancy related to interval cancer, cancer not detectable by CT, and nodules present but not identified.

2 Benign nodule

Safe to return to screening

Nodule < 5mm

Perifissural opacities

Benign calcification

Core biopsy benign

Solid and stable for 2 yrs

Subsolid stable for 5 yrs

Round atelectasis definite

Hamartoma definite

Safe to return to annual screening.

Risk of malignant diagnosis prior to next screen very low.

No benefit for earlier follow up.

3 Indeterminate

Requires serial LDCT


5-9 mm non-enlarging solid nodule with < 2 years stability.

5-9 mm subsolid nodule with < 5 years stability.

Follow as per schedule (Fleischner or screening-specific guidelines. Note some suggest following new nodules more closely than baseline nodules)



Baseline or new nodule > 10 mm with any possibility of transient inflammatory process.

e.g., new or baseline subsolid nodules >10 mm

e.g., Inflammatory clinical or CT features (rapid development, multifocal, satellite nodules, air bronchogram, OR ground glass border)

Do short interval follow up (4 to 12 weeks) to allow transient inflammatory process an opportunity to improve or resolve.

No improvement is worrisome (reclassify into category 4).

4 Suspicious

4A Low risk of malignancy

Solid nodule ( > 10mm) with benign features but CT not definitive for category 2.

e.g., probable round atelectasis; well-defined roughly spherical nodule possibly hamartoma or granuloma.

Review all possibly relevant prior imaging.

Needs work up. At minimum follow at 3 months. REFER

Other possibilities:

Core biopsy, PET (negative PET reassuring in this category Value of + PET dependent on rate of granulomatous disease.)


4B Likely low grade adenocarcinoma

Non-resolving subsolid opacity > 10 mm

(with solid component < 5mm)

Risk of pre-invasive or minimally invasive disease high.

REFER. Surgical biopsy/resection vs. annual screen if stable.

PET and biopsy not routinely recommended (high false negatives)

Biopsy if non surgical treatment.


4C Likely malignant

Worrisome persistence

Non-resolving part solid nodule > 10 mm (solid portion > 5 mm)

OR Worrisome change

Malignant growth rate in solid nodule or portion

OR Worrisome baseline

Lobulated or spiculated entirely solid nodule > 10mm with no inflammatory CT or clinical features, no ground glass border.

Risk of malignancy very high in high risk screening population.


Benefit of PET is in staging not diagnosis.

Negative PET, bronchoscopy or biopsy is discordant and should prompt multidisciplinary review.

5 Malignant by CT

Invasion of chest wall or mediastinum.

As per 4C

6 Tissue malignant

E.g., positive FNA, core, bronch, or surgical resection

False positive results possible but very rare with FNA.

Assuming patient remains a treatment candidate and no regular CT for disease surveillance, continued screening recommended.


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