Fig. 6.

A CT reconstruction of thorax from individual with pectus excavatum. B The Haller index is calculated by dividing the transverse diameter of the chest by the anterior–posterior distance of the chest on an axial CT slice where the distance between the anterior surface of the vertebral body and the posterior surface of the sternum is the shortest. In this case, the index is 22/6 = 3.67 (severe pectus excavatum). Normal chest: < 2.0, mild excavatum: 2.0–3.2, moderate excavatum: 3.2–3.5, and severe excavatum: > 3.5