Companion shadows

Last revised by Mostafa Elfeky on 17 Jul 2023

Companion shadows are smooth, homogeneous, radiopaque shadows running parallel along the bones. In a study of 700 chest radiographsBen Felson found that 75% had companion shadows on the lower ribs 3.

Radiographic features

They appear secondary to soft tissues and intercostal muscles running along 3:

Practical points

Companion shadows need to be differentiated from periosteal reactions secondary to adjacent bony or soft tissue pathology.

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