Toward accessible quantification of bone mineral density: feasibility of radiographic bone aluminum equivalence (RBAE) determined by digital radiography against DEXA and CT in translational sheep model
Aug 2026· BMC Medical Imaging· Vol 26· 0 citations· 35 references
Medicine
TL;DR
Digital radiography, supported by standardized calibration and analysis, yields a reproducible BMD estimates that align closely with DEXA and CT measurements, which highlights DR as a cost-effective and accessible option for BMD assessment, while providing valuable baseline insight into normal mineral distribution.
Abstract
The study aimed to explore an accessible quantification of bone mineral density (BMD) through Radiographic Bone Aluminium Equivalence (RBAE) as determined by Digital Radiography (DR), compared to dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT) in ex vivo animal model. Metacarpal and metatarsal bones (n = 24) from skeletally mature sheep were imaged using standard DR, DEXA, and CT protocols. DR-derived BMD values were calculated from calibrated greyscale intensities using an aluminum step-wedge and image-analysis workflow. Correlation and regression analyses were performed to evaluate the relationship between the different modalities, whereas the intraclass correlation coefficient (ICC) and Bland–Altman analyses were used to assess agreement between the measurement methods. DR-derived BMD as expressed as BRAE demonstrated strong linear correlation with DEXA (r = 0.779, p = 0.001) and moderate linear correlation with CT (r = 0.536, p = 0.04). Across all imaging modalities, metatarsal bones exhibited significantly higher BMD than metacarpal bones, with clear bilateral symmetry observed within each bone type. The consistency of results across modalities strengthens the validity of the findings and supports the reliability of each technique for detecting biologically meaningful differences in BMD. The agreement between DEXA, CT and digital radiography underscores the feasibility of using radiographic BMD to quantify BMD. Digital radiography, supported by standardized calibration and analysis, yields a reproducible BMD estimates that align closely with DEXA and CT measurements. These findings highlight DR as a cost-effective and accessible option for BMD assessment, while providing valuable baseline insight into normal mineral distribution. This information supports future research on pathological bone loss, imaging validation, and therapeutic strategies to improve bone quality.
Purpose
Children with chronic illness are vulnerable to compromised bone health. Dual-energy X-ray absorptiometry (DXA) is commonly used for assessment but has limitations related to body size adjustments and positioning, highlighting the need for accessible alternatives. This study evaluated the correlation between the Bone Health Index (BHI), derived from automated hand radiograph analysis, and areal bone mineral density (BMD) measured by DXA in Chinese children with chronic illness.
Methods
In this retrospective study, Chinese children undergoing simultaneous DXA and hand radiography were included. Correlations between BHI metrics and DXA-derived BMD Z-scores were assessed.
Results
A total of 327 patients were analyzed. Absolute BHI values showed negligible correlation with DXA-derived BMD at the lumbar spine (LS) (r = 0.10, p = 0.05) and total body less head (TBLH) (r = 0.00, p = 0.35). BHI standard deviation scores (SDS) exhibited moderate positive correlations with DXA BMD Z-scores (LS: r = 0.42, p <0.001; TBLH: r = 0.43, p <0.001). In steroid-treated patients, these correlations were weaker (LS: r = 0.30, p =0.007; TBLH: r = 0.30, p 0.001). Conversely, steroid-naïve patients exhibited stronger correlations (LS: r = 0.48, p<0.001; TBLH: r = 0.53, p<0.001).
Conclusion
In steroid-treated patients, BHI SDS correlated weakly with DXA-derived BMD Z-scores, whereas steroid-naïve patients exhibited moderate correlations. This highlights that BHI and DXA BMD assess distinct bone properties that are differentially influenced by systemic treatment like glucocorticoids. Consequently, BHI should be regarded as a complementary tool rather than serving as a direct surrogate for DXA.
J. Tung, Pakanut Pitupan, S. W. Poon et al.· Annals of Pediatric Endocrin...· 0 citations
INTRODUCTION
Dual-energy quantitative computed tomography (DE-QCT) enables the quantitative measurement of bone mineral density (BMD), but the in vivo precision of these measurements remains largely unexplored. Voxel-based morphometry (VBM) provides a framework for assessing BMD precision at the voxel level, offering spatial detail that is not available using conventional region-based methods. This study aimed to evaluate the absolute and relative precision of DE-QCT-based BMD measurements at regional and voxel levels for future studies of knee osteoarthritis.
METHODS
Thirty healthy participants (20 female; mean age = 35.7 ± 12.5 years) underwent two same-day bilateral DE-QCT knee scans with repositioning between scans. Scans were calibrated to provide quantitative measures of BMD, and the femur, tibia, and patella were segmented for analysis. Regional precision was assessed by comparing scan-rescan mean BMD values using root-mean-square standard deviation (SDRMS) and root-mean-square percent coefficient of variation (CVRMS), with least significant change (LSC) calculated for both metrics. Voxel-wise precision was evaluated using the same metrics following spatial normalization and Gaussian smoothing with 5 mm and 8 mm full-width-at-half-maximum (FWHM) kernels.
RESULTS
Regional precision was high, with pooled precision estimates across the three bones yielding low LSC values, ranging from 7.08-9.97 mg HA/cm3 (LSC SDRMS) and ≤ 3.03% (LSC CVRMS). At the voxel level, LSC SDRMS was generally low and relatively uniform throughout each bone, with mean values ranging 6.02-6.58 mg HA/cm3 at 5 mm FWHM smoothing and 4.83-5.40 mg HA/cm3 at 8 mm FWHM smoothing across the three bones. Voxel-wise CVRMS exhibited greater spatial variability, with the highest values observed in the femoral and tibial metaphyses.
CONCLUSION
Using DE-QCT, we provided spatial maps of reproducibility for voxel-wise BMD measurements in the distal femur, proximal tibia, and patella. At the voxel level, SDRMS provides a more stable and interpretable precision metric than CVRMS and is recommended for voxel-based comparisons.
Nina Pavlovic, Julio Carballido-Gamio, Yousif Al-Khoury et al.· Bone· 0 citations
Both HU and VBQ offer useful assessments of vertebral bone quality, but HU provides higher and more stable diagnostic accuracy, demonstrating higher sensitivity, specificity, and accuracy for detecting osteopenia and osteoporosis.
Omar Lubbad, Akram Hagos, Laila Lubbad et al.· European Radiology· 0 citations
Introduction: Osteoporosis is a systemic skeletal disorder that increases the risk of fragility fracture and constitutes a major global health burden. Dual-Energy X-Ray Absorptiometry (DEXA) is the clinical reference standard for Bone Mineral Density (BMD) assessment but, as a two-dimensional projection technique, does not directly evaluate trabecular microarchitecture or marrow composition. Magnetic Resonance Imaging (MRI) signal characteristics of vertebral marrow have been proposed as opportunistic markers of Vertebral Bone Quality (VBQ).
Aim: To evaluate the correlation between lumbar spine MRI signal alterations (T1- and T2-weighted) and DEXA-derived BMD parameters, including BMD, T-score and Z-score, in patients undergoing lumbar spine imaging.
Materials and Methods: A cross-sectional analytical study was conducted at Assam Down Town University, Guwahati, Assam, India, from October 2023 to April 2024. A total of 100 adults of either sex who underwent both lumbar spine MRI (1.5 Tesla) and DEXA were evaluated. A circular Region Of Interest (ROI) of 1 cm² was placed in the central trabecular portion of the L3 vertebral body on T1- and T2- weighted sagittal images, avoiding cortical bone, end-plate changes and focal lesions. DEXA-derived BMD was classified according to World Health Organisation (WHO) T-score criteria. Pearson’s correlation coefficient with 95% Confidence Intervals (CI) was used to assess associations; a two-tailed p-value <0.05 was considered significant.
Results: The cohort comprised 52 females (52%) and 48 males (48%). Based on lumbar (L1-L4) T-scores, 42 (42%) participants had normal BMD, 31 (31%) osteopenia and 27 (27%) osteoporosis. Reduced BMD was more frequent among females and older participants. The T-score showed weak but statistically significant negative correlations with T1-weighted (r=-0.214; 95% CI -0.394 to -0.018; p-value=0.033) and T2- weighted (r=-0.208; 95% CI -0.389 to -0.012; p-value=0.038) signal values. The Z-score correlated strongly with mean BMD (r=0.685; 95% CI 0.565 to 0.777; p-value <0.001); as the Z-score is derived from BMD, this served as an internal consistency check.
Conclusion: Lumbar vertebral MRI signal alterations showed weak but statistically significant associations with DEXAderived BMD, suggesting that routinely acquired lumbar MRI may provide supplementary, opportunistic information on VBQ. The modest strength of these correlations indicates that MRI signal cannot currently replace DEXA for the diagnosis of osteoporosis.
Amit Sarma, Mrinal Singha· Journal of Clinical and Diag...· 0 citations
Osteoporosis is a progressive skeletal disorder characterized by reduced bone mineral density (BMD) and increased risk of fragility fractures. Clinical assessment relies primarily on dual-energy X-ray absorptiometry (DXA) and the Fracture Risk Assessment Tool (FRAX), but limited access and low screening rates motivate investigation of complementary approaches. This human cadaveric study evaluated cortical indices of the second metacarpal, radius, and femur in relation to DXA-based osteoporosis status and biomechanically derived fracture susceptibility at the wrist and hip. Cortical measurements were obtained from 39 donor-matched forearms and femurs categorized as normal (n = 8), osteopenic (n = 11), and osteoporotic (n = 20) based on femoral neck DXA T-score. Simulated fall testing of the distal radius and proximal femur was performed to determine work to fracture, which was used to derive low and high biomechanical fracture susceptibility classifications. Among the cortical indices, metacarpal cortical index (MCI) demonstrated the strongest associations with DXA T-scores and biomechanical outcomes. MCI distinguished normal from osteoporotic classification at the femoral neck (area under the curve (AUC) = 0.938) and 1/3 radius (AUC = 0.986). For biomechanically derived fracture susceptibility, femoral neck T-score demonstrated strong discrimination at both the femur (AUC = 0.917) and wrist (AUC = 0.851), while MCI yielded AUCs of 0.847 and 0.855, respectively. FRAX hip fracture (HF) probability yielded AUCs of 0.911 at the femur and 0.830 at the wrist. These findings demonstrate associations between MCI, DXA-based osteoporosis status, and biomechanical fracture susceptibility in this cadaveric cohort. MCI may therefore warrant further investigation as a complementary screening approach, particularly where access to DXA is limited. Validation in larger clinical cohorts with prospective fracture outcomes is needed to determine its clinical utility.
Anthony J. Yosick, Sophia L. Turbide, Andrew J. Berger et al.· JBMR Plus· 0 citations
VBQ can serve as an opportunistic exploratory screening marker of low BMD and FBQcsf may complement VBQ by identifying early marrow-related changes, although further validation is required.
M. Müller, João Paulo Ferreira, Laura Mulazzani Minuzzi Macedo et al.· Skeletal Radiology· 0 citations
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