Least significant change as an essential tool for monitoring of bone mineral density using dual energy X-ray absorptiometry

Abstract

Dual-energy X-ray absorptiometry (DXA) scans are the gold standard for measuring bone mineral density (BMD). It is accepted that precision error is crucial in monitoring BMD measurements. The least significant change (LSC) signifies the minimum difference between two consecutive BMD measurements that can confidently indicate a genuine biological change. This value provides direct benefit to patients by aiding clinicians in making clinical decisions based on real change or stability of BMD. This study aimed to determine the LSC for DXA scan used at Udonthani Cancer Hospital. We conducted a cross-sectional study in 150 patients undertaking DXA scans performed by one of our five radio-technologists from March 2023 to September 2023. Each technologist assessed BMD study of 30 participants twice, obtaining paired BMD measurements for the lumbar vertebrae, hip, and forearm. We utilized the copy of region of interest (ROI) software to replicate the ROI. The LSC was calculated with a 95% CI using both the RMS SD and RMS %CV formulas. The obtained LSC were 3.26% for the L1-L4 vertebrae, 4.40% for the femoral neck, 2.30% for the total proximal femur, and 5.30% for the 33% radius, meeting 2019 International Society for Clinical Densitometry (ISCD) standards. Nevertheless, the ISCD 2019 guidelines do not provide acceptable value for determining the LSC at the 33% radius. The higher variability in measurements at the femoral neck and the 33% radius emphasizes the need for continuous professional development and enhanced reproducible methods to improve the precision of BMD measurement using DXA scans.