Opportunistic assessment of volumetric bone mineral density (vBMD) from computed tomography (CT) scans offers a strategy to identify individuals at risk of osteoporosis. However, accurate CT-based vBMD quantification depends on appropriate density calibration, and direct comparisons of synchronous, asynchronous, and tissue-based internal calibration in low-dose chest imaging are limited. This study had two objectives: (1) to assess the impact of calibration methods on image quality in low-dose chest CT, particularly whether the inclusion of a calibration phantom compromises image quality, and (2) to examine whether these variations influence agreement in vBMD measurements across calibration techniques. 51 participants underwent chest CT; 23 with a calibration phantom (synchronous) and 28 without (asynchronous). Trabecular vBMD was quantified at the fourth and eighth thoracic vertebrae (T4 and T8, respectively) and the first lumbar vertebra (L1). Image quality was assessed using stochastic noise and signal-to-noise ratio (SNR) in calibration phantom rods and tissue-based reference regions. Agreement in vBMD measurements was evaluated using Pearson’s correlation coefficients, Bland–Altman analyses, and absolute deviations relative to internal calibration. Internal calibration tissues demonstrated stable image quality across synchronous and asynchronous acquisitions, whereas synchronously scanned calibration phantoms exhibited increased noise and reduced SNR. In vBMD measurements, asynchronous calibration demonstrated smaller deviations (19.15 ± 11.59 mg cm−3 vs. 10.19 ± 9.69 mg cm−3) than synchronous across vertebral levels. These findings show that calibration strategy affects both image quality and vBMD agreement in low-dose chest CT. Asynchronous and tissue-based internal methods provided more consistent estimates than synchronous calibration, supporting their use for opportunistic osteoporosis assessment.
B. Matheson, M. Walle, S. Boyd· Medical Engineering and Phys...· 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
OBJECTIVE
To gain insight into higher fracture risk in individuals with type 2 diabetes, we determined the association of type 2 diabetes glycemic status and severity with longitudinal changes in peripheral bone density and microarchitecture.
RESEARCH DESIGN AND METHODS
We conducted a longitudinal study of 769 participants from the Framingham Study who underwent high-resolution, peripheral, quantitative computed tomography (HR-pQCT) at the tibia and radius, in 2012-2016 and 2021-2023 (mean 8-year follow-up). Linear regression models estimated mean 8-year percent changes in bone measures, across indicators of diabetes severity, adjusting for age, sex, weight, and height.
RESULTS
The mean age was 67 ± 7 years, and 59% of participants were women. More than half (57%) were normoglycemic (fasting plasma glucose [FPG] <100 mg/dL, not on any treatment), 31% had prediabetes (100 ≤ FPG ≤125 mg/dL), and 12% had type 2 diabetes (FPG >125 mg/dL or on treatment). Adjusted mean percent changes in HR-pQCT bone measures were similar across diabetes severity, including glycemic status, use of diabetes medications, duration of diabetes, and HbA1c. For example, cortical volumetric bone mineral density at the radius changed by -1.50% (95% CI -2.43, -0.56) in type 2 diabetes and -1.96% (-2.53, -1.39), in prediabetes, compared with -2.42% (-2.86, -1.97) in normoglycemia (reference group; all P > 0.05).
CONCLUSIONS
The magnitude of peripheral bone loss over 8 years did not differ between individuals with type 2 diabetes and those with normoglycemia, suggesting that bone deterioration alone does not explain the higher fracture risk in older adults with type 2 diabetes. Future studies should address other contributors to skeletal fragility.
A. Dufour, M. Bouxsein, Mu-Song Gao et al.· Diabetes Care· 0 citations
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