Haller index is defined as which ratio?

Haller index is defined as which ratio?

• A. Transverse diameter / AP diameter
• B. AP diameter / Transverse diameter
• C. Lateral diameter / AP diameter
• D. Circumference / AP diameter

Answer: (A)

The Haller index gauges the severity of chest wall deformity by comparing how wide the chest is to how deep it is. On axial imaging, you measure the transverse (width) diameter—the widest left-to-right distance across the chest—and the anteroposterior (AP) diameter—the distance from the sternum to the posterior spine. The index is the ratio of the transverse diameter to the AP diameter. A larger ratio means the chest is relatively wide and shallow, which corresponds to a more pronounced pectus excavatum deformity. Normal values are around the mid-2s, while values above about 3.25 are often considered indicative of a deformity severe enough to consider surgical correction. This ratio is specifically defined as transverse diameter divided by AP diameter, not the reverse. Using the reciprocal or other measurements like a lateral diameter or circumference does not reflect the same anatomic relationship used to assess the depth of the chest deformity.

The Haller index gauges the severity of chest wall deformity by comparing how wide the chest is to how deep it is. On axial imaging, you measure the transverse (width) diameter—the widest left-to-right distance across the chest—and the anteroposterior (AP) diameter—the distance from the sternum to the posterior spine. The index is the ratio of the transverse diameter to the AP diameter. A larger ratio means the chest is relatively wide and shallow, which corresponds to a more pronounced pectus excavatum deformity. Normal values are around the mid-2s, while values above about 3.25 are often considered indicative of a deformity severe enough to consider surgical correction.

This ratio is specifically defined as transverse diameter divided by AP diameter, not the reverse. Using the reciprocal or other measurements like a lateral diameter or circumference does not reflect the same anatomic relationship used to assess the depth of the chest deformity.