Wavelet transform-based photoacoustic time-frequency spectral analysis for bone assessment

Weiya Xie; Ting Feng; Mengjiao Zhang; Jiayan Li; Dean Ta; Liming Cheng; Qian Cheng

doi:10.1016/j.pacs.2021.100259

Wavelet transform-based photoacoustic time-frequency spectral analysis for bone assessment

Photoacoustics. 2021 Mar 10:22:100259. doi: 10.1016/j.pacs.2021.100259. eCollection 2021 Jun.

Authors

Weiya Xie^{1

2}, Ting Feng^{1

3}, Mengjiao Zhang¹, Jiayan Li¹, Dean Ta⁴, Liming Cheng², Qian Cheng^{1

2}

Affiliations

¹ Institute of Acoustics, School of Physics Science and Engineering, Tongji University, Shanghai, PR China.
² The Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration, Ministry of Education, Department of Orthopaedics, Tongji Hospital, Tongji University School of Medicine, Shanghai, PR China.
³ School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing, PR China.
⁴ Department of Electronic Engineering, Fudan University, Shanghai, PR China.

Abstract

In this study, we investigated the feasibility of using photoacoustic time-frequency spectral analysis (PA-TFSA) for evaluating the bone mineral density (BMD) and bone structure. Simulations and ex vivo experiments on bone samples with different BMDs and mean trabecular thickness (MTT) were conducted. All photoacoustic signals were processed using the wavelet transform-based PA-TFSA. The power-weighted mean frequency (PWMF) was evaluated to obtain the main frequency component at different times. The y-intercept, midband-fit, and slope of the linearly fitted curve of the PWMF over time were also quantified. The results show that the osteoporotic bone samples with lower BMD and thinner MTT have higher frequency components and lower acoustic frequency attenuation over time, thus higher y-intercept, midband-fit, and slope. The midband-fit and slope were found to be sensitive to the BMD; therefore, both parameters could be used to distinguish between osteoporotic and normal bones (p < 0.05).

Keywords: ARTB, area ratio of trabecular bone; BMD, bone mineral density; Bone assessment; CWT, continuous wavelet transform; DEXA, dual energy X-ray absorptiometry; EDTA, ethylenediaminetetraacetic acid; MTT, mean trabecular thickness; PA, photoacoustic; PA-TFS, photoacoustic time-frequency spectrum; PA-TFSA, photoacoustic time-frequency spectral analysis; PWMF, power-weighted mean frequency; Photoacoustic measurement; QUS, quantitative ultrasound; ROI, region of interest; Time-frequency spectral analysis; US, ultrasound; Wavelet transform.