Yuan Xu

BSc, MSc, PhD
Associate Professor

Specialization

Medical imaging

Research Projects

It is desirable to image the electrical properties of biological tissues non-invasively with high spatial resolution because the electrical properties of biological tissues are closely related with the physiological and pathological status of the tissues. Several methods have been proposed to image the electrical impedance at low-frequency range, such as electrical impedance tomography (EIT). Pure microwave and optical imaging modalities have been used to probe the absorption rate of biological tissues to electromagnetic waves, which depends on both the tissue conductivity and the tissue permittivity at the corresponding electromagnetic frequency. However, all the above imaging modalities that employ pure electromagnetic waves suffer from either low spatial resolution or poor imaging depth.

My research goal is to develop a high-spatial-resolution imaging modality to map the electrical properties of biological tissues. In the past few years, I have been focused on two imaging modalities: thermoacoustic tomography (photoacoustic tomography) and magnetoacoustic tomography with magnetic induction. The idea behind these two methods is that by utilizing both electromagnetic waves and acoustic waves we can combine the good contrast of the pure electromagnetic approaches with the good spatial resolution of pure ultrasound approaches. My future research interest includes developing the above two imaging methods for clinical applications and exploring new methods to implement the idea of combining electromagnetic approaches with acoustic approaches.

Selected Publications

1. O. Doganay, Y. Xu, “Reversibility of Electric-Field Induced Mechanical Changes (EIMC) in Soft Tissues,” IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, in press, 2012.

2. O. Doganay, Y. Xu, “Electric-field induced strain in biological tissues,” Journal of the Acoustical Society of America Express Letters, 128(5), EL261 – 267, 2010.

3. E. Renzhiglova, V. Ivantsiv, Y. Xu, “Difference Frequency Magneto-Acousto-Electrical Tomography (DF-MAET): application of ultrasound-induced radiation force to imaging electrical current density,” IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 57(11) 2391-2401, 2010.

4. S. Haider, A. Hrbek, Y. Xu, “Magneto-acousto-electrical tomography: a potential method for imaging current density and electrical impedance,” Physiological Measurement, 29(6):S41-50 (2008).

5. Y. Xu, S. Haider, A. Hrbek, “Magneto-Acousto-Electrical Tomography: A New Imaging Modality for Electrical Impedance,” 13th International Conference on Electrical Bioimpedance combined with the 8th Conference on Electrical Impedance Tomography, in Graz (Austria), 2007.

6. X. Li, Y. Xu, and B. He, “Imaging Electrical Impedance from Acoustic Measurements by Means of Magnetoacoustic Tomography with Magnetic Induction (MAT-MI),” IEEE Transactions on Biomedical Engineering, 54(2) 323–330 (2007).

7. X. Li, Y. Xu, B. He, “Magnetoacoustic tomography with magnetic induction for imaging electrical impedance of biological tissue,” JOURNAL OF APPLIED PHYSICS, 99 (6): Art. No. 066112 (2006).

8. Y. Xu and L.-H. V. Wang, “Rhesus monkey brain imaging through intact skull with thermoacoustic tomography,” IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 53(3) 542–548 (2006).

9. Y. Xu and B. He, “Magnetoacoustic tomography with magnetic induction,” Phys. Med. Bio. 50 (21), 5175–5187 (2005).

10. X. Jin, Y. Xu, and et al., “Preliminary results of visualizing HIFU-induced lesions in soft tissue with thermoacoustic tomography,” Medical Physics 32 (1): 5–11 (2005).

11. Y. Xu and L.-H. V. Wang, “Time reversal and its application to tomography with diffracting sources,” Physical Review Letters, 92 (3), 033902 (2004).

12. Y. Xu and L.-H. V. Wang, “Reconstructions in limited-view thermoacoustic tomography,” Medical Physics, 31 (4), 724–733 (2004)

13. Y. Xu and L.-H. Wang, “Effects of acoustic heterogeneity in breast thermoacoustic tomography,” IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 50 (9), 1134–1146 (2003).

14. Y. Xu, D. Feng, and L. Wang, “Exact frequency-domain reconstruction for thermoacoustic tomography: I. Planar geometry,” IEEE Transactions on Medical Imaging, 21 (7), 823–828 (2002).

15. Y. Xu, M. Xu, and L. Wang, “Exact frequency-domain reconstruction for thermoacoustic tomography: II. Cylindrical geometry,” IEEE Transactions on Medical Imaging, 21 (7), 829–833 (2002).

16. X. Wang, Y. Xu, M. Xu, S. Yokoo, E. S. Fry and L.-H. Wang “Photoacoustic tomography of biological tissues with high cross-section resolution: Reconstruction and experiment,” Medical Physics, 29 (12), 2799–2805 (2002).

17. Y. Xu and L. Wang, “Signal processing in scanning thermoacoustic tomography in biological tissues,” Medical Physics 28 (7), 1519–1524 (2001).

Funding

• Ryerson Startup Fund
• NSERC

Group Members

Current Graduate students:
Elyas Shaswary
Valentin Demidov

Current Undergraduate students:
Zahid Panchbhaya
Arash Moghimi
Wojciech Wysocki

Current Research Assistant:
Ozkan Doganay

Alumni:
Andrew Hrbek (M.A.Sc. 2009)
Syed Faizan Haider (M.A.Sc. 2008)
Elena Renzhiglova (M.A.Sc. 2009)
Ozkan Doganay (M.A.Sc. 2010)
Aditya Pandya (M.A.Sc. 2012)
Vitaliy Ivantsiv
Monirul Sajib
Krzysztof WAWRZYN
Arjit Baghwala
Barry Vuong
Yuan Yang
Chenguang Yang