Thoracic Pleural Reflections and the Inferior Pulmonary Ligament on CT

A practical radiology review of Thoracic Pleural Reflections and the Inferior Pulmonary Ligament on CT, focused on imaging findings, differential diagnosis, reporting points, and high-yield teaching pearls.

Why these landmarks matter

Pleural reflections and ligamentous attachments can mimic linear disease, accessory fissures, or soft-tissue bands on CT. Recognizing their expected location improves confidence when evaluating the lower mediastinum, lung bases, and diaphragmatic surfaces.

Pleural reflection over the right phrenic nerve

On axial CT, the pleural reflection may be visible lateral to the inferior vena cava as it courses over the right phrenic nerve. Follow the structure across adjacent slices before labeling it as a pathologic band or pleural lesion.

Inferior pulmonary ligament

The inferior pulmonary ligament is a double layer of pleura extending inferiorly from the pulmonary hilum. On axial and coronal images it may appear as a thin linear structure below the lower pulmonary veins. It can be contiguous with intersegmental septa and may be accompanied by pericardiophrenic bundles or accessory fissures.

Practical CT checklist

• Review axial and coronal planes together.
• Trace a suspected pleural line across consecutive images.
• Confirm its relationship to the hilum, lower pulmonary veins, diaphragm, and mediastinum.
• Avoid calling a normal reflection a scar, septal thickening, or accessory fissure without multiplanar confirmation.

Distinguishing normal anatomy from disease

A normal pleural reflection should follow a predictable anatomic course and remain thin without nodularity, mass effect, or adjacent inflammatory change. Compare soft-tissue and lung windows and use multiplanar reformats when its course is uncertain. Focal thickening, nodular enhancement, pleural effusion, distortion, or a line that does not track with expected pleural anatomy warrants a broader differential. Prior surgery, infection, pleurodesis, and volume loss can also alter these landmarks and should be incorporated into the interpretation.