The Diagnostic Utility of CT Attenuation Values in Detecting Calcification Within Costal Cartilage

Background To establish and verify diagnostic criteria for the identification of costal cartilage calcification based on CT attenuation value. Methods 360 chest CT slices of 120 patients were reviewed and annotated retrospectively and ROC curve was used to evaluate the diagnostic ability of CT attenuation value. Another 20 slices containing calcification were randomly selected and annotated by 4 doctors for further validation. H&E and COLX staining was performed on the residual costal cartilage. Results In total 355129 voxels were detected and 187.5 was confirmed as the optimal CT attenuation value threshold, with a sensitivity of 98.6% and a specificity of 99.7%, for costal cartilage calcification diagnosis. Threshold-based identification of calcification demonstrated a similarity of nearly 80% with specialists' assessments, and exhibited advantages in the identification of subtle calcifications in the further validation. We also observed that CT attenuation values among males demonstrated a centralized distribution, whereas those among females exhibited a bimodal distribution. Threshold-based identified calcification showed a positivity of COLX. Conclusions CT attenuation value could validly and reliably diagnose calcification within costal cartilage. Further investigations involving larger cohorts of patients are required to elucidate the risk factors and underlying mechanisms of costal cartilage calcification.