Table 4. Differentiation of acute and chronic pulmonary thromboembolism—CT pulmonary angiography findings.

CTPA findings	Acute	Chronic
Vascular signs	Central or eccentric filling defect; acute angle with vessel wall; preserved caliber of the artery or expanded secondary to pulsatile flow	Peripheral, crescent-shaped filling defect; obtuse angle with vessel wall; webs, bands, calcified thrombus; vessel narrowing or amputation, intimal irregularities
Collateral vessels	Absent	Bronchial and non-bronchial systemic arteries dilatation
Pulmonary hypertension signs	May be present; however, without right ventricle hypertrophy	Commonly present
Parenchymal signs	Pulmonary infarction (“reversed halo sign”)	Pulmonary scars from prior infarction; mosaic lung attenuation

CTPA, computed tomography pulmonary angiography.