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Incidental Mediastinal / Cardiovascular (ACR)

Guided recommendation from the ACR Incidental Findings Committee white paper on mediastinal and cardiovascular findings at thoracic CT (Munden et al., JACR 2018). Pick the finding and answer the questions.

Applies to asymptomatic adults (≥18 y) imaged for an unrelated reason. Do not apply if signs or symptoms relate to the finding, or if lymphoma is clinically suspected (e.g., "B" symptoms). Covers six domains: mediastinal lymph node, mediastinal mass, pericardial abnormality, thoracic aortic dilation, coronary artery calcification, and pulmonary artery dilation. Recommendations, not standard of care.

Source thresholds & figures

Mediastinal lymph node (Fig 1)

Short axis < 15 mm or benign texture (fatty hilum, calcification, smooth margins) → no further work-up. ≥ 15 mm: explainable disease → management per that disease; no explainable disease → clinical consultation and/or FDG PET/CT and/or 3–6 month follow-up CT (increased → PET/CT or biopsy; stable/decreased → no further work-up).

Mediastinal mass (Fig 2)

Anterior/middle compartment: cystic → no further work-up; not cystic → MRI or PET/CT. Posterior compartment → MRI (high likelihood of neurogenic origin).

Pericardial abnormality (Fig 3)

Cyst HU ≤ 10 → no further work-up. Cyst HU > 10, thickened pericardium (> 3–4 mm), effusion > 50 mL, or calcification: explainable disease → management per disease; no explainable disease → consider MRI or short-term CT follow-up.

Thoracic aorta (text)

Ascending aorta and root: dilated 4.0–4.4 cm, aneurysm ≥ 4.5 cm, on absolute size. The 2022 ACC/AHA aortic disease guideline replaces the 1.5×-expected-normal rule here, because it fails in these two segments, and prefers “dilated” to “ectatic”. Descending: the 1.5× rule still holds — upper-normal ≈ 3.0 cm, aneurysm ≥ 4.0 cm; gender-dependent. Diameter ≥ 5.5 cm → high rupture risk, consider intervention. Connective-tissue disease (Marfan/Ehlers-Danlos) with ascending ≥ 5.0 cm → consider prophylactic aortic root replacement.

Coronary artery calcification (text)

Report presence/absence in all patients (Agatston or visual none/mild/moderate/heavy-severe). Heavy or severe CAC should be further evaluated.

Pulmonary artery (text)

Main pulmonary artery ≥ 3.0 cm, or equal to/greater than the ascending aorta diameter, should be reported as dilated. May reflect pulmonary arterial hypertension or be secondary to chronic PE / lung disease.

Munden RF, et al. Managing Incidental Findings on Thoracic CT: Mediastinal and Cardiovascular Findings. A White Paper of the ACR Incidental Findings Committee. J Am Coll Radiol 2018;15:1087–1096.