Infant with fever and respiratory distress

CXR and MRI of pulmonary sequestration
CXR shows a large round opacity in the left lower lobe that abuts the diaphragm. Coronal T1 MRI with contrast of the chest shows a uniformly enhancing mediastinal mass that extends into the retrocrural regions of the chest bilaterally and that has a feeding vessel arising from the aorta.

The diagnosis was pulmonary sequestration (extralobar).