Table 2.

Differential diagnosis table of unilateral pulmonary artery agenesis

	CXR	CT	MRI	V/Q Scan	Angiography
Pulmonary artery agenesis	Contracted hemithorax Hyperlucent lung Ipsilateral mediastinal shift Elevated hemidiaphragm Small hilum	Absent pulmonary artery Hyperaerated opposite lung Collateral circulation	Absent pulmonary artery Reduced ipsilateral pulmonary vasculature Collateral circulation	Reduced or normal ventilation and absent perfusion	Complete atresia of one pulmonary artery Aortogram depicts collaterals
Swyer-James syndrome	Contracted hemithorax Hyperlucent lung Inspiratory mediastinal shift toward, expiratory shift away Small hilum	Air-trapping with reduced vascularity	‘Pruned-tree’ appearance of ipsilateral pulmonary vasculature	Reduced or normal perfusion and markedly reduced ventilation in the affected segments	Diminished size of affected pulmonary artery Collaterals uncommon
Chronic pulmonary thrombo embolism	Contracted hemithorax Hypolucent lung Diminished vasculature	Mural thrombus, ‘polo-mint’ sign Mosaic perfusion Findings of pulmonary hypertension	Findings and measurement of pulmonary hypertension	Abnormal perfusion scan with normal ventilation	Large central pulmonary arteries with marked peripheral tapering
Congenital pulmonary hypoplasia	Contracted hemithorax Hyperlucent lung Small hilum Associated vertebral anomalies	Hypoplastic ipsilateral pulmonary artery and airways Hyperaerated opposite lung Associated cardiac abnormalities	Hypoplastic ipsilateral pulmonary artery and airways Lung volume estimation	Perfusion defects and reduced or normal ventilation	Patent but hypoplastic pulmonary artery