Varghese Tomy

Position: Assistant Professor

Education:

• B. E., Instrumentation Technology, University of Mysore, India, 1988.

• M.S., Electrical Engineering, University of Kentucky, 1992

• Ph.D., Electrical Engineering, University of Kentucky, 1995.

• Post-Doctoral Fellow, Radiology, University of Texas Medical School-Houston, 1995-2000.

Professional Affiliations:

• Senior Member, Institute of Electrical and Electronics Engineers (IEEE).

• Member, American Institute of Ultrasound in Medicine (AIUM). 

• Associate Member, Indian Institute of Engineers (AMIE).

Research Interests:

• Elastography.

• Signal & Image Processing Applications in Medical Imaging.

• Ultrasound Tissue Characterization.

Publications:

Reviews & Invited Articles:

· J. Ophir, F. Kallel, Tomy Varghese, M. Bertrand, I. Céspedes and H. Ponnekanti, "Elastography: A systems approach", Invited paper & Review, The International Journal of Imaging Systems and Technology, John Wiley & Sons, Inc, Vol. 8, pp. 89-103, 1997.

· E. E. Konofagou, Tomy Varghese, and J. Ophir, "Using variable compressions with a combined baseband method for dynamic range expansion of elastograms", Invited paper, Journal of Medical Ultrasonics, The Japan Soc. Ultrason. Med., Vol. 24, No. 5, pp. 753-760, 1997.

· J. Ophir, K. A. Alam, B. Garra, F. Kallel, E. E. Konofagou, T. A. Krouskop, and Tomy Varghese, "Elastography: Ultrasonic estimation and imaging of the elastic properties of tissues", Invited paper & Review, Proceedings of the Institution of Mechanical engineers, Part H Journal of Engineering in Medicine, Vol. 213, pp. 203-233,1999.

· J. Ophir, B. Garra, F. Kallel, E. E. Konofagou, T. A. Krouskop, R. Righetti and Tomy Varghese, "Elastographic Imaging", Invited Paper, Ultrasound in Medicine and Biology, Vol. 26, Supplement 1, pp. S23-S29, 2000.

Refereed Journal Articles:

· K.D. Donohue. J. M. Bressler, Tomy Varghese, and N. M. Bilgutay, "Spectral correlation in ultrasonic pulse-echo signal processing", IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Vol.-40, pp. 330-337, 1993.

· Tomy Varghese, and K. D. Donohue,  "Characterization of tissue microstructure scatterer distribution with spectral correlation", Ultrasound Imaging Vol.-15, pp. 238-254, 1993.

·Tomy Varghese, and K. D. Donohue, "Mean scatterer spacing estimates with spectral correlation", Journal Acoustic Society America, Vol. 96, No. 6, pp. 3504-3515, 1994.

·Tomy Varghese, and K. D. Donohue, "Estimating mean scatterer spacing with the frequency-smoothed spectral autocorrelation function", IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Vol. 42, No. 3, pp. 451-463, 1995.

· M. Wang, L. G. Hassebrook, J. Evans, Tomy Varghese, and C. Knapp, "An optimized index of human cardiovascular adaptation to simulated weightlessness", IEEE Transactions on Biomedical Engineering, Vol.  43, No. 5, pp. 502-511, 1996.

·Tomy Varghese, K. D. Donohue, V. L. Genis, and E. J. Halpern, "Order selection criteria for detecting mean scatterer spacing with the AR model", IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Vol. 43, No. 5, pp. 979-984, 1996.

· Tomy Varghese, and Jonathan Ophir,  "Performance optimization in elastography: Multicompression with temporal stretching", Ultrasonic Imaging, Vol. 18, No. 3, pp. 193-214, 1996.

· Tomy Varghese, J. Ophir, and E. I. Céspedes, "Noise reduction in elastography using temporal stretching with multicompression averaging", Ultrasound in Medicine and Biology, Vol. 22, No. 8, pp. 1043-1052, 1996.

· Tomy Varghese, and J. Ophir, "Estimating tissue strain from signal decorrelation using the correlation coefficient", Ultrasound in Medicine and Biology, Vol. 22, No. 9, pp. 1249-1254, 1996.

· Tomy Varghese, and J. Ophir, "A theoretical framework for performance characterization of elastography: The strain filter", IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Vol. 44, No. 1, pp. 164-172, 1997.

·  Tomy Varghese, and J. Ophir, "Enhancement of echo-signal correlation in elastography using temporal stretching", IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Vol. 44, No. 1, pp. 173-180, 1997.

· E. E. Konofagou, J. Ophir, F. Kallel, and Tomy Varghese, "Elastographic dynamic range expansion using variable applied strains", Ultrasonic Imaging, Vol. 19, No. 1, pp. 145-166, 1997.

· Tomy Varghese, and J. Ophir, "The nonstationary strain filter in elastography, Part-I, Frequency dependent attenuation", Ultrasound in Medicine and Biology, Vol. 23, No. 9, pp. 1343-1356, 1997.

· F. Kallel, Tomy Varghese, J. Ophir and M. Bilgen,  "The nonstationary strain filter in elastography, Part-II, Lateral and elevational decorrelation", Ultrasound in Medicine and Biology, Vol. 23, No. 9, pp. 1357-1369, 1997.

·Tomy Varghese, M. Bilgen, and J. Ophir, "Multiresolution imaging in elastography", IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Vol. 45, No. 1, pp. 65-75, 1998.

· Tomy Varghese, and J. Ophir, "Characterization of elastographic noise using the envelope of echo signals ", Ultrasound in Medicine and Biology, Vol. 24, No. 4, pp. 543-555, 1998.

· Tomy Varghese, and J. Ophir, "An analysis of the elastographic contrast-to-noise ratio performance", Ultrasound in Medicine and Biology, Vol. 24, No. 6, pp. 915-924, 1998.

· S. K. Alam, J. Ophir, E. I. Céspedes, and Tomy Varghese, “A deconvolution filter for improvement of time-delay estimation in elastography,” IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Vol. 45, No. 6, pp. 1565-1572, 1998.

· Tomy Varghese, and J. Ophir, "Method for the experimental characterization of the noise performance of elastographic systems", Ultrasonic Imaging, Vol. 21, No. 1, pp. 17-30, 1999.

· E. E. Konofagou, Tomy Varghese, J. Ophir, and S. K. Alam "Power spectral strain estimators in elastography", Ultrasound in Medicine and Biology, Vol. 25, No. 7, pp. 1115-1129, 1999.

· S. K. Alam, J. Ophir, and Tomy Varghese “Elastographic axial resolution criteria: An experimental study,” IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, Vol. 47, No. 1, pp. 304-309, 2000.

· E. E. Konofagou, Tomy Varghese, and J. Ophir, "Spectral estimators in elastography", Ultrasonics, Vol. 38, No. 1-8, pp. 412-416, 2000.

· Tomy Varghese, J. Ophir, and T A. Krouskop "Non-linear stress-strain relationships in tissue and their effect on the contrast-to-noise ratio in elastograms", Ultrasound in Medicine and Biology, Vol. 26, No. 5, pp. 839-851, 2000.

·  Tomy Varghese, J. Ophir, E. E. Konofagou, S. K. Alam and M. Bilgen "Direct strain estimation in elastography using spectral cross-correlation", Ultrasound in Medicine and Biology, (in press), 2000.

Invited Presentations:

·        J. Ophir, Tomy Varghese, F. Kallel, S. K. Alam, and E. E. Konofagou "Elastography: A quantitative description of tradeoffs in the imaging of tissue strain", Invited Presentation & Abstract, Proceedings of the 17^th International Conference, Her Anba Congress Centinium, Technical University of Delft, The Netherlands, June 1997.

·        J. Ophir, K. A. Alam, B. Garra, F. Kallel, E. E. Konofagou, and Tomy Varghese, "Elastography: Imaging of tissue elastic properties in vivo", Invited Presentation & Abstract, IEEE Ultrasonics Symposium, pp. 000-000, October 5-8, 1998, Sendai, Japan.

·        J. Ophir, F. Kallel, E. E. Konofagou, T. Krouskop, B. Garra, and Tomy Varghese, " Fundamentals of elastographic imaging and their applications: A tutorial", Invited Tutorial, Presentation & Abstract, 17^th Annual Houston Conference on Biomedical Engineering Research, Sponsored by the Houston Society for Engineering in Medicine and Biology, February 11-12, 1999.

·        Tomy Varghese, J. Ophir, E. E. Konofagou, and F. Kallel, "Fundamental framework for elastographic imaging", Invited Tutorial & Abstract, 17^th Annual Houston Conference on Biomedical Engineering Research, Sponsored by the Houston Society for Engineering in Medicine and Biology, February 11-12, 1999.

Awards & Honors

·        Sigma Xi Research Day Best Poster Award:  J. Ophir, E. E. Konofagou, Tomy Varghese, F. Kallel, S. K. Alam, and I. Céspedes, "Elastography: A quantitative method for imaging the elasticity of biological tissue", April 3, University of Houston, 1997.

·        Member, Eta Kappa Nu (Electrical Engineering Honor Society).

·        Outstanding Teacher evaluation, Letter of appreciation, Dean, University of Kentucky, Lexington, KY, 1994.

·        Recipient, Raja Ramanna Gold Medal, Best Outgoing Student, in Instrumentation Technology, University of Mysore, Mysore, India, 1988.

Summary

My primary research interests are in signal and image processing applications in medical imaging for the early detection of cancer. Early detection of cancers can significantly improve patient survival rate and lead to effective treatment. The aim of this research project is to develop signal-processing tools for extracting relevant tissue microstructure information embedded in the spectra of RF broadband ultrasonic echoes.  The ultimate goal is to provide fast, reliable and well-understood signal processing techniques for the early detection of malignant tissue using ultrasound.  A unique aspect of this research is its focus on characterizing Fourier phase and magnitude of RF ultrasonic echoes with spectral redundancy characterized by the spectral autocorrelation function (also called the Generalized Spectrum).  Disruptions in the normal structure of liver and breast tissue due to invading cancers, are detected by examining the changes in the quasi-periodic nature of the liver tissue and the presence of specular scatterers (calcifications in malignant tissue) in breast tissue using this innovative approach. This method is more accurate than the traditional techniques used to estimate the scatterer spacing.

My current research deals with the development of Elastography. Elastography is rapidly developing into a new ultrasonic imaging modality, capable of producing images of internal strain or tissue elasticity.   Elastography is a method for imaging the elastic properties of compliant tissues, producing gray scale strain images referred to as elastograms. You can think of Elastography as a “high tech” form of palpation. Elastography has been used for imaging and characterizing tumors in the breast, prostate, kidney, liver, muscle and other tissues. Ultrasonic visualization is widely used in practically all-medical specialties.  The proposed technique could therefore have a large impact on medical practice in the United States.  Elastograms have also been obtained using MRI, and Optical Coherence Tomographic (OCT) methods.

We are currently looking for students to work on several new research projects. The research field involves tissue characterization and basic and applied elastographic imaging of tissues using ultrasound.