Osteoporosis: Pathophysiology and New Drug Development

Application of full waveform inversion algorithm in Laplace-Fourier domain for high-contrast ultrasonic bone quantitative imaging

BACKGROUND AND OBJECTIVES

Full waveform inversion (FWI) has been widely applied for the reconstruction of underground medium parameters in seismic communities and has made a great success. It is also a promising way to image hard tissues such as bones by ultrasonic FWI algorithm. However, the ultrasonic FWI methods for bone parameters imaging reported in literature so far are limited to the time domain and/or Fourier domain, and can only achieve quantitative imaging with acoustic velocity of bone less than 3000 m/s. Because the acoustic velocity of actual cortical bones can be as high as 4200 m/s, it is still a challenge for FWI to achieve higher parameter contrast bone imaging.

METHODS

Here, we proposed an ultrasonic FWI algorithm in Laplace-Fourier domain (LFDFWI) for high-contrast bone quantitative imaging. Compared to Time domain and Fourier domain, the LFDFWI algorithm is more appropriate for dealing with the presence of high contrast between bone tissues, reducing the possibility of inversion falling into a local minimum, and obtaining better inversion results. We adapted the seismic FWI algorithm to make it suitable for high-frequency ultrasonic sources and small-sized bone parameter imaging.

RESULTS

We conducted a series of bone models to evaluate the effectiveness of the proposed algorithm, including four kinds of bone model derived from micro computed tomography (Micro-CT) image of rat. We evaluated the experimental results based on visual analysis, error analysis and structural similarity (SSIM). The numerical simulation results showed that, when acoustic approximation is used, the proposed method can obtain accurate high-contrast images of the velocity and density parameters of bone structure, the mean relative error (MRE) in the region of interest (ROI) were all less than 2%, and the SSIM is up to 98%; when the viscoelastic approximation is used, this method can also obtain the desired high-contrast bone parameter distribution, with MRE less than 4% and SSIM higher than 74%, both of which are better than FDFWI in Fourier domain (FDFWI).

CONCLUSION

The results demonstrated that the proposed FWI algorithm can obtain high resolution bone parameter models close to the Micro-CT image, which proves its clinical application potential.

Cryptotanshinone Suppressed Postmenopausal Osteoporosis by Preventing RANKL-Mediated Osteoclastogenesis against Kidney Injury

Background

Cryptotanshinone (CPT), an active component extracted from the root of Salvia miltiorrhiza Bunge, exhibits extensive favorable bioactive properties including anti-inflammatory, antioxidative, antibacterial, and antitumor effects. This study aims to investigate the effects of CPT on osteogenesis and explore related mechanisms both in vivo and in vitro.

Methods

In the in vivo experiment, ovariectomized (OVX) female rats were intragastrically administered with CPT at doses of 10 mg/kg and 20 mg/kg for 13 consecutive weeks. Dual-energy X-ray absorptiometry was employed to detect bone mineral density (BMD). ELISA assay was leveraged to detect the biochemical parameters such as BUN and creatinine in the kidney samples. Bone and kidney sections were dyed by H&E and Masson staining kits. In the in vitro experiment, the RAW 264.7 cells were stimulated through the receptor activation of the nuclear factor kappa B ligand (RANKL) to establish an osteoclast differentiation model, and CPT's protective effect against bone loss was evaluated. Differentiated osteoclasts were determined by TRAP staining. While, osteoclast-marker proteins such as NFATc1, c-Fos, and cathepsin K were identified by Western blot.

Results

The results from in vivo experiments revealed that CPT could elevate bone mass and increase bone formation markers in OVX rats. Intriguingly, CPT administration noticeably ameliorated the kidney injury in OVX rats by suppressing BUN and restoring creatinine levels. Furthermore, the results from in vitro experiments suggested that CPT downregulated the protein expression of osteoclast-associated genes such as cathepsin K, c-Fos, and NFATc1 which hinted the related potential mechanisms.

Conclusion

The evidence from in vivo and in vitro experiments suggested that CPT exerted antiosteoclastogenic effects by inhibiting the activation of osteoclast differentiation followed by suppressing the protein expressions of cathepsin K, c-Fos, and NFATc1 in osteoclast precursors, and it exhibited protective effects against kidney damage, which highlighted its advantage in clinical application.