MRI-based distal femur cortical thickness analysis for osteoporosis detection.

OBJECTIVES

This study aims to evaluate the presence of osteoporosis by measuring the distal femur cortex thickness on routine knee MRI performed for any reason. We aim to determine if these measurements can serve as a reliable indicator of bone mineral density (BMD) and thus facilitate early diagnosis of osteoporosis.

METHODS

A retrospective study was conducted with approval from the hospital's Ethics Committee. Patients who underwent dual-energy X-ray absorptiometry (DXA) and knee MRI within 6 months were included. Exclusion criteria were patients under 18, those with a gap of more than 6 months between scans, prior knee surgeries, trauma, bone tumours, or non-diagnostic MRI results. MRI examinations were performed on a 1.5 Tesla scanner. Measurements included average cortical bone thickness (CBTavg), distal femoral cortical index-1 (DFCI-1), and distal femoral cortical index-2 (DFCI-2). A radiologist blinded to DXA scores conducted the measurements. Statistical analyses were performed using the Mann-Whitney U test and receiver operating characteristic (ROC) analysis.

RESULTS

A total of 74 patients were included. Significant differences were found between the normal BMD group and the osteopenia/osteoporosis group for CBTavg, DFCI-1, and DFCI-2 (P < 0.01). ROC analysis showed high diagnostic accuracy with an area under the curve (AUC) of 0.92 for CBTavg, 0.90 for DFCI-1, and 0.91 for DFCI-2. Optimal cut-off values were determined as 4.52 mm for CBTavg, 2.58 mm for DFCI-1, and 1.12 mm for DFCI-2.

CONCLUSION

The study demonstrates that osteopenia/osteoporosis can be effectively diagnosed using distal femur cortex thickness measurements on routine knee MRI. These measurements provide a simple, fast, and practical method for opportunistically detecting osteoporosis, facilitating early intervention and management.

ADVANCES IN KNOWLEDGE

This study is the first to demonstrate that distal femur cortex thickness measurements on routine knee MRI can effectively predict osteoporosis, offering a novel, opportunistic screening method that enhances early detection and intervention strategies.