Reliability of a standardized protocol to calculate cross-sectional chest area and severity indices to evaluate pectus excavatum.

Purpose: In evaluating the impact of surgical repair of pectus excavatum, the Haller index developed for preoperative decision-making purposes may be inadequate to quantify postoperative changes in shape of the chest. Individual patients may also have chest characteristics that impact the success of repair, many of whichwouldbeunlikelytobemeasuredbytheHallerindexalone.Wehavedevelopedaprotocolthatmeasures the cross-sectional chest area and the asymmetry index along with the Haller index to more completely quantify the nature of the deformity. The purpose of this study was to determine the reliability of this protocol in the interpretation of chest computed tomography images from multiple sites. The protocol wasdevelopedaspartofamulticenterstudyofclinicaloutcomesaftersurgicalrepairofpectusexcavatum. Methods:Two radiologists independently selected 5 images from each of 32 computed tomography scans frommulticenterstudyparticipantsaccordingtotheprotocol.Adigitizerwasusedtomeasurethediameters and cross-sectional areas of the images selected; these results were used to calculate the Haller and asymmetry indices. The protocol was tested for intradigitizer and interradiologist reliability. Using the Haller andasymmetryindices,wealsoassessedagreementbetweenradiologistsclassifyingpatientsasabnormal. Results:Agreement wasuniformlyhighfor allcomparisons (allLin’s concordance coefficientsN0.99and all Cohen’s j’s N0.85, all agreement on classification of patients N95%) indicating almost perfect agreement. Disagreement onclassification ofpatients using the Haller andasymmetry indexwas at the cut points for abnormality.