Opportunistic CT-based osteoporosis screening of the hip: a systematic review of diagnostic accuracy.

INTRODUCTION

Osteoporosis is a major public health concern characterized by diminished bone mass and an increased fracture risk, yet its timely diagnosis remains challenging due to underutilization of Dual-energy X-ray Absorptiometry (DXA). Opportunistic screening using Computed Tomography (CT) images obtained for other indications offers a promising alternative for identifying patients at risk of fractures. This systematic review aims to evaluate the diagnostic accuracy of opportunistic osteoporosis screening using hip, pelvic, and abdominal CT scans, with a focus on measurements at the proximal femur.

MATERIALS AND

METHODS

A systematic review was conducted to evaluate the use of opportunistic CT imaging of the hip for osteoporosis screening, following a search of PubMed, EMBASE, and MEDLINE databases up to January 2024 using PRISMA guidelines. All studies evaluating the diagnostic accuracy of CTs including the hip to diagnose osteopenia/osteoporosis were included. The outcomes assessed were: the correlation between CT-derived Hounsfield Units (HU) and DXA-derived Bone Mineral Density (BMD), and the diagnostic accuracy of CT-derived metrics to diagnose osteopenia/osteoporosis.

RESULTS

The systematic review included 16 studies with 6,772 patients (mean age 43.5-81.9 years), predominantly females (73%). Correlations between CT-derived HU values and DXA-derived BMD were strong across studies, with correlation coefficients up to 0.947. Diagnostic performance for osteoporosis was generally superior to that for osteopenia, with AUC values up to 0.987 and variability in cut-off values (e.g., 54-425 HU for the hip), highlighting significant differences across regions of interest and methodologies.

CONCLUSION

This review shows opportunistic hip CT has promise for osteoporosis detection, with strong correlations to DXA and high reported accuracy. However, wide variability in HU thresholds and lack of standardized protocols mean current evidence is insufficient for clinical implementation. Until acquisition methods and calibration are standardized and validated, opportunistic CT should not replace DXA but remains a potential complementary tool.