Table 2.

Main grading basis of PNI-GARS

Item	Details
Size	Basic standard of grading, the larger the diameter of the nodules, the higher the possibility of malignancy
Margin	Smooth: I; Partial smooth: II; Lobulation: III; Short spinous protrusion: IV
Density	Calcification: 0 (higher than pulmonary vascular, similar to ribs) Solid: I (similar to pulmonary vascular); Non solid: II(lower than pulmonary vascular, higher than pulmonary parenchyma) Partial solid: III (III ≤5 mm, IV > 5 mm);
Periphery	In the same lung lobe, there are satellite lesions: fibrosis, calcification, nodules, exudation, consolidation, etc., and the grade score is decreased one level
Endobronchial nodules	Grade III
Special signs of early malignant lesions (III: 1 signs;IV: ≥ 2 signs)	A.Vacuole sign B. Vascular convergence sign C. A solid component of GGN
Other suspicious signs of malignancy	Spiculation, GGN that doubles in 1 year or its density more than − 600 Hu, enlarged lymph nodes, size of nodule reduced but density increased during follow-up, etc.
Clinical or CT findings suggest possible inflammation	Clinical infection symptoms: A history of respiratory system infection in the past 3 months; Respiratory system symptoms have appeared at recent, and the lesions change rapidly. CT signs of inflammation: vague or unclear margin, high density in the center and ground glass density of edge, multiple lesions, satellite lesions, Tree-in-Bud sign.

GGN ground-glass nodule