The feasibility study of the transmission mode photoacoustic measurement of human calcaneus bone in vivo

Abstract

The photoacoustic (PA) technique is uniquely positioned for biomedical applications primarily due to its ability to visualize optical absorption contrast in deep tissue at ultrasound resolution. In this work, via both three-dimensional (3D) numerical simulations and in vivo experiments on human subjects, we investigated the possibility of PA measurement of human calcaneus bones in vivo in a non-invasive manner, as well as its feasibility to differentiate osteoporosis patients from normal subjects. The results from the simulations and the experiments both demonstrated that, when one side of the heel is illuminated by laser with light fluence under the ANSI safety limit, the PA signal generated in the human calcaneus bone can be detected by an ultrasonic transducer at the other side of the heel (i.e. transmission mode). Quantitative power spectral analyses of the calcaneus bone PA signals were also conducted, demonstrating that the microarchitectural changes in calcaneus bone due to osteoporosis can be detected, as reflected by enhanced high frequency components in detected PA bone signal. Further statistical analysis of the experimental results from 10 osteoporosis patients and 10 healthy volunteers showed that the weighted frequency as a quantified PA spectral parameter can differentiate the two subject groups with statistical significance.

Theoretical and experimental study of attenuation in cancellous bone

“… 90 – 92 In addition, the diameter of calcaneus bone in the human body is in the range of 2 to 3 cm. 43 The attenuation of the cancellous bone to the high-frequency PA signal is stronger, and the received signal is mainly concentrated in the lower frequency band between 220 kHz and 1 MHz. According to the numerical simulation results shown in Fig.…”

“…Using the SoS to calculate the thickness of these three types of media and employing the exponential attenuation law to consider the optical and ultrasonic propagation attenuation of cortical bone and soft tissue, we can compensate the PA signals in further studies to isolate and analyze the pure PA signal corresponding to cancellous bone 90 – 92 In addition, the diameter of calcaneus bone in the human body is in the range of 2 to 3 cm 43 . The attenuation of the cancellous bone to the high-frequency PA signal is stronger, and the received signal is mainly concentrated in the lower frequency band between 220 kHz and 1 MHz.…”

“…41 The SoS for the first arriving wave in the tibia showed a strong correlation with the SoS value based on QUS. 42 Feng et al 43 simulated various aspects of PA in skeletal tissues, including light attenuation and distribution, along with PA signal generation and propagation, based on a three-dimensional model. They proposed a PA physicochemical spectral method for assessing changes in the chemical composition and microstructure of cancellous bone.…”

“…The SoS for the first arriving wave in the tibia showed a strong correlation with the SoS value based on QUS 42 . Feng et al 43 . simulated various aspects of PA in skeletal tissues, including light attenuation and distribution, along with PA signal generation and propagation, based on a three-dimensional model.…”

Development of a semi‐anthropomorphic photoacoustic calcaneus phantom based on nano computed tomography and stereolithography 3D printing

“…13,14 More recently, via both computational modeling and a clinical study on a small cohort of 20 subjects including 10 normal volunteers and 10 osteoporosis patients, our group validated the feasibility of PA measurement combined with QUS, that is, PAQUS, for assessment of both chemical properties and microarchitecture of human calcaneus in vivo. 15,16 Encouraged by the success in this initial clinical study, our group is working on further development and commercialization of the PAQUS technology.…”