External caliper-based measurements of the modified percent depth as an alternative to cross-sectional imaging for assessing the severity of pectus excavatum

This prospective study validates external caliper measurements (Modified Percent Depth) as an accurate alternative to cross-sectional imaging for assessing pectus excavatum severity in children aged 11-21. The MPD demonstrated comparable diagnostic accuracy to traditional radiographic indices (Haller Index, Correction Index) with high interrater reliability, potentially reducing unnecessary imaging exposure in pediatric patients.