Intervals between bone mineral density testing with dual-energy X-ray absorptiometry scans in clinical practice

Index-Rotated Fast Ultrasound Imaging of Cortical Bone Based on Predicted Velocity Model

Due to the significant acoustic impedance contrast at cortical boundaries, highly inside attenuation, and the unknown sound velocity distribution, accurate ultrasound cortical bone imaging remains a challenge, especially for the traditional pulse-echo modalities using unique sound velocity. Moreover, the large amounts of data recorded by multielement probe results in a relatively time-consuming reconstruction process. To overcome these limitations, this article proposed an index-rotated fast ultrasound imaging method based on predicted velocity model (IR-FUI-VP) for cortical cross section ultrasound tomography (UST) imaging, utilizing ray-tracing synthetic aperture (RTSA). In virtue of ring probe, the sound velocity model was predicted in advance using bent-ray inversion (BRI). With the predicted velocity model, index-rotated fast ultrasound imaging (IR-FUI) was further applied to image the cortical cross sections in the sectors corresponding to the dynamic apertures (DAs) and ring center. The final result was merged by all sector images. One cortical bone phantom and two ex vivo bovine femurs were utilized to demonstrate the performance of the proposed method. Compared to the conventional synthetic aperture (SA) imaging, the method can not only accurately image the outer cortical boundary but also precisely reconstruct the inner cortical surface. The mean relative errors of the predicted sound velocity in the region of interest (ROI) were all smaller than 7%, and the mean errors of cortical thickness are all less than 0.31 mm. The reconstructed images of bovine femurs were in good agreement with the reference images scanned by micro-computed tomography ( μ CT) with respect to the morphology and thickness. The speed of IR-FUI is about 3.73 times faster than the traditional SA. It is proved that the proposed IR-FUI-VP-based UST is an effective way for fast and accurate cortical bone imaging.

Fourier-Domain Ultrasonic Imaging of Cortical Bone Based on Velocity Distribution Inversion

There is a significant acoustic impedance contrast between the cortical bone and the surrounding soft tissue, resulting in difficulty for ultrasound penetration into bone tissue with high frequency. It is challenging for the conventional pulse-echo modalities to give accurate cortical bone images using uniform sound velocity model. To overcome these limitations, an ultrasound imaging method called full-matrix Fourier-domain synthetic aperture based on velocity inversion (FM-FDSA-VI) was developed to provide accurate cortical bone images. The dual linear arrays were located on the upper and lower sides of the imaging region. After full-matrix acquisition with two identical linear array probes facing each other, travel-time inversion was used to estimate the velocity distribution in advance. Then, full-matrix Fourier-domain synthetic aperture (FM-FDSA) imaging based on the estimated velocity model was applied twice to image the cortical bone, utilizing the data acquired from top and bottom linear array, respectively. Finally, to further improve the image quality, the two images were merged to give the ultimate result. The performance of the method was verified by two simulated models and two bone phantoms (i.e., regular and irregular hollow bone phantom). The mean relative errors of estimated sound velocity in the region-of-interest (ROI) are all below 12%, and the mean errors of cortical section thickness are all less than 0.3 mm. Compared to the conventional synthetic aperture (SA) imaging, the FM-FDSA-VI method is able to accurately image cortical bone with respect to the structure. Moreover, the result of irregular bone phantom was close to the image scanned by microcomputed tomography ( μ CT) in terms of macro geometry and thickness. It is demonstrated that the proposed FM-FDSA-VI method is an efficient way for cortical bone ultrasonic imaging.

Factors Associated With Bone Density Monitoring While on Antiosteoporosis Treatment in Routine Clinical Practice: A Registry-Based Cohort Study

The role for bone mineral density (BMD) monitoring while on antiosteoporosis therapy remains controversial. The current study used population-based registries to identify factors associated with BMD monitoring in women within 5 yr of receiving antiosteoporosis treatment vs treatment without monitoring in routine clinical practice. The analytical dataset consisted of women age 40 yr and older at baseline receiving antiosteoporosis therapy: 6877 with BMD monitoring (mean interval 3.2 yr) and 6747 without BMD monitoring. There was a significant negative secular trend in BMD monitoring during the study period (p < 0.001). Multivariable logistic regression demonstrated that parental hip fracture, glucocorticoid and aromatase inhibitor use, and lower baseline BMD were independently and positively associated with BMD monitoring. Individuals with increasing age, greater body mass index, smoking, rheumatoid arthritis, later calendar year, diabetes, rural residency, lower income, and greater comorbidity score were less likely to undergo monitoring. A shorter monitoring interval (<23 mo) was strongly associated with glucocorticoid and aromatase inhibitor use. In conclusion, our study identifies factors associated with BMD monitoring over 5 yr in patients receiving antiosteoporosis therapy.

Association of Bone Density Monitoring in Routine Clinical Practice With Anti-Osteoporosis Medication Use and Incident Fractures: A Matched Cohort Study

Routine bone mineral density (BMD) monitoring of individuals during the initial 5 years of anti-osteoporosis treatment is controversial. Using a registry-based cohort from the Province of Manitoba, Canada, we compared anti-osteoporosis medication use and fracture outcomes in women with versus without BMD monitoring receiving anti-osteoporosis medication. We identified 4559 women aged 40 years and older receiving anti-osteoporosis therapy with serial BMD testing (monitoring) within 5 years (mean interval 3.2 years) and 4559 propensity score-matched women without BMD monitoring. We assessed anti-osteoporosis medication use over 5 years from a population-based retail pharmacy database. Incident fractures to 10 years from health services data. During median 10 years observation, 1225 (13.4%) women developed major osteoporotic fracture, including 382 (4.2%) with hip fractures. Monitored women had significantly better fracture-free survival for major osteoporotic fracture (p = 0.040; 10-year cumulative risk 1.9% lower, 95% confidence interval [CI] 0.3-3.6%) and hip fracture ( p = 0.001; 10-year cumulative risk 1.8% lower, 95% CI 0.7-2.8%) compared with women who were not monitored. Hazard ratios (HRs) were significantly lower in monitored versus not monitored women for major osteoporotic fracture (HR = 0.89, 95% CI 0.80-0.98) and hip fracture (HR = 0.74, 95% CI 0.63-0.87). Days of medication use, medication persistence ratio, and treatment switching over 5 years were greater in monitored versus not monitored women. At the end of 5 years, more women in the monitored group persisted on treatment and more switched treatment, with switching behavior associated with an observed interval reduction in BMD. In conclusion, our findings suggest a possible role for BMD monitoring after initiating anti-osteoporosis therapy in the routine clinical practice setting. © 2019 American Society for Bone and Mineral Research.