Quantitative computerized tomography for the diagnosis of osteopenia in prehistoric skeletal remains

Abstract

In this study, we examine the value of bone density assessed by computed tomography (QCT) of the right tibia in the diagnosis of low bonemass in prehistoric bones. Trabecular bone mass (TBM) was assessed by histomorphometry in undecalcified bone sections of a small part of theproximal epiphysis of the right tibia of 78 prehispanic individuals. Bone density was also assessed in the proximal epiphysis of the right tibia, inan area of cancellous bone immediately adjacent to the wedge which was destined to histomorphometry, with the aid of a Tomoscan 60 TXÔ(Philipps Medical System, Eindhoven, The Netherlands) using a phantom of hydroxyapatite included in plastic resin at three known concentra-tions (50, 100 and 200 mg/cc) and ethanol as fat equivalent. Bone density (as bone hydroxyapatite concentration in milligram per cubic centi-meter) was calculated by means of a specific software tool (QCT Bone Mineral Analysis System, Image Analysis, California). We comparedbone density assessed with QCT with TBM in these individuals, and also, with the results obtained from a modern control group. We calculatedthe median TBM of the prehispanic sample and tested the sensitivity, specificity, and overall accuracy of QCT in diagnosing TBM values belowthe median. We later performed the same analyses on 24 more prehispanic individuals. Both QCT (t¼5.61,p<0.001) and TBM (t¼3.79,p<0.001) were significantly lower among the prehispanic individuals than among the control ones. QCT showed a significant relationshipwith TBM (r¼0.41,p<0.001). QCT values below 100 mg/cc serve to establish a diagnosis of low TBM values with a sensitivity of 82.1%and a specificity of 41%. In the test group sensitivity was 83.3% and specificity, 50%.In conclusion, in contrast with the results obtained in clinical studies, QCT serves only to obtain a rough estimate of TBM in prehistoricsamples. The relatively low accuracy may be due to the lack of soft tissue and the air bubbles entrapped within the cancellous bone, which persisteven after prolonged submersion of the bones in a water bath.Ó2006 Elsevier Ltd. All rights reserved.