Baseline screening LDCT: largest finding is a 4 mm solid nodule. Category and management:
Lung-RADS 1 — annual screening; Lung-RADS 2 — annual screening; Lung-RADS 3 — 6-month LDCT; Lung-RADS 4A
Answer: Lung-RADS 2 — annual screening. Solid nodules under 6 mm at baseline are category 2 (benign appearance/behavior): continue ANNUAL screening. Category 1 is no nodules at all (or definitely benign calcified ones).
Baseline 7 mm solid nodule:
4A — LDCT at 3 months; 4B — workup now; 2 — annual; 3 — LDCT at 6 months
Answer: 3 — LDCT at 6 months. Solid 6 to <8 mm at baseline is category 3 ('probably benign'): low-dose CT at 6 months. Growth at that scan moves it up; stability steps it back down.
Baseline 10 mm solid nodule:
2; 3; 4A — 3-month LDCT, PET-CT may be considered; 4B
Answer: 4A — 3-month LDCT, PET-CT may be considered. Solid 8 to <15 mm is 4A: 3-month LDCT, with PET-CT an option when the solid component is ≥8 mm. 15 mm and above (or growing 4A) is 4B territory — diagnostic CT, PET-CT and/or sampling.
The 4X modifier means:
Additional features raising suspicion beyond the size category (e.g., spiculation, adenopathy); The patient missed a scan; A benign calcified nodule; The exam was incomplete
Answer: Additional features raising suspicion beyond the size category (e.g., spiculation, adenopathy). 4X is category 3 or 4 imaging PLUS findings that make it more suspicious than size alone implies — spiculation, lymphadenopathy, frank metastatic appearance. It mandates the aggressive 4B-style pathway.
The S modifier is for:
Prior surgery; Small airways disease; Suspicious nodules; Clinically significant non-lung-cancer findings (e.g., severe coronary calcification, aortic aneurysm)
Answer: Clinically significant non-lung-cancer findings (e.g., severe coronary calcification, aortic aneurysm). S flags significant incidental findings outside the screening question. It rides alongside the category (e.g., 2S) and obliges the report to say what the finding needs.
Category 0 means:
Incomplete — prior CTs needed or technically inadequate; Benign nodule; Patient refused; Negative exam
Answer: Incomplete — prior CTs needed or technically inadequate. 0 = incomplete: awaiting comparison priors or a nondiagnostic acquisition. It is a tracking state, not a result — the audit expects it resolved, not accumulated.
A category 3 nodule is unchanged at the 6-month LDCT. Next:
Return to annual screening (category 2 behavior); Escalate to 4A; PET-CT; Stay 3 forever
Answer: Return to annual screening (category 2 behavior). Stability downgrades: a stable probably-benign finding returns the patient to the annual pathway. Growth, by contrast, re-categorizes by the new size/behavior.
New 5 mm solid nodule appearing on an ANNUAL repeat screen:
4A; Ignore if under 6 mm; 2 — annual; 3 — 6-month LDCT
Answer: 3 — 6-month LDCT. Thresholds differ for NEW nodules: a new solid nodule 4 to <6 mm on a repeat exam is category 3. New growth is inherently more suspicious than a stable baseline finding of the same size.
Pure ground-glass nodule, 25 mm, at baseline screening:
Not covered by Lung-RADS; Category 2 — annual screening; Category 3 — 6-month LDCT; Category 4A
Answer: Category 2 — annual screening. Lung-RADS v2022 treats pure ground-glass nodules as indolent: a GGN under 30 mm is category 2 with annual screening, however striking it looks. Only at 30 mm or larger (or on development of a solid component) does a GGN reach category 3 — a sharp contrast with the solid-nodule thresholds twenty times smaller.
A 6 mm nodule found on a contrast-enhanced CT ordered for trauma should be managed by:
No framework applies; Lung-RADS 2; Lung-RADS 3; Fleischner 2017
Answer: Fleischner 2017. Lung-RADS exists only inside an organized screening program. Incidental nodules on diagnostic CTs are Fleischner territory — citing Lung-RADS there mis-sets both the interval and the audit.