January 8, 2019
A paper co-authored by graduate student Fernando Zvietcovich and Professor Kevin Parker, and collaborators Professor Natalie Baddour (University of Ottawa) and Professor Jannick Rolland (UR Institute of Optics) titled "Shear wave propagation in viscoelastic media: validation of an approximate forward model" has been published by Physics in Medicine and Biology, and can be found here. The work described in the article reconsiders a previous analytical model with the goal of obtaining a computationally straightforward and efficient equation for the propagation of shear waves from a focal push pulse. This model is compared with an experimental OCT system and with finite element models. The results support the use of an efficient form of the Hankel transform for both lossless (elastic) and lossy (viscoelastic) media, and for both impulsive and extended push pulses that can model a range of experimental conditions.
September 12, 2018
Congratulations to PhD candidate Fernando Zvietcovich, who received two prestigious student awards at the 2018 International Tissue Elasticity Conference held in Avignon, France from 9-12 September 2018. Fernando received the 1st place award in the "Best Student Oral Presentation" category for his presentation titled "Reverberant 3D optical coherence elastography (REV3D-OCE): a novel method for the 3D elastic mapping of layers in cornea." Fernando also received the "Best Poster" award for his presentation titled "Gaussian shear wave propagation in viscoelastic media: validation of an approximate forward model." The full list of ITEC student award winners can be found here.
September 11, 2018
A patent applied for by Professor Kevin Parker and former graduate student Dr. Shujie Chen was issued on September 11, 2018. The patent is titled "Superresolution imaging of scatterers in pulse-echo imaging with symmetric stabilized pulses" and more information can be found here.
September 9, 2018
PhD candidates Juvenal Ormachea and Fernando Zvietcovich attended and presented at the International Tissue Elasticity Conference (ITEC) held in Avignon, France from 9-12 September 2018. Ormachea and Zvietcovich presented the following:
September 5, 2018
A paper co-authored by Professor Kevin Parker, graduate student Juvenal Ormachea, and Dr. Zaegyoo Hah of Samsung Medison Co. Ltd. titled "Group versus phase velocity of shear waves in soft tissues" has been e-published by Ultrasonic Imaging, and can be found here. The article describes the distinction between group and phase velocities, and the importance of that distinction to the field of elastography. For the class of tissues and materials exhibiting power law dispersion, group velocity is significantly greater than phase velocity, and simple expressions are shown to interrelate the commonly measured parameters. Examples are given from phantoms and tissues.
August 21, 2018
A manuscript co-authored by Dr. P. Ted Christopher and Professor Kevin Parker titled "The nonlinear ultrasound needle pulse" was published online by the Journal of the Acoustical Society of America, and can be found here. The work presented compared a focused 3 MHz broadband Gaussian beam against a corresponding needle pulse field by utilizing the output of a nonlinear propagation model. The results suggest that the unique convergence of the needle pulse to a narrow but extended axial line in linear propagation is also inherited by higher harmonics in nonlinear propagation. Further, the linear needle field's relatively short duration focal pulses also hold for the associated higher harmonics. The needle pulse's focal features may prove to be useful in some future applications where an extended depth of field and narrow beam width are advantageous.
August 6, 2018
Professor Kevin Parker has received a grant from the National Institutes of Health to further refine his H-scan ultrasound technology, which matches different classes of echoes from various cells and structures to different display colors. This makes it easier for clinicians to visualize and recognize subtle changes between normal and diseased tissues. The NIH funding will enable Professor Parker to address optimization issues to establish the technology as a viable diagnostic technique. Co-investigators on the project include Dr. Michael Drage in the Department of Pathology and Laboratory Medicine and Dr. Hongmei Yang of the Department of Biostatistics and Computational Biology.
May 29, 2018
Professor Kevin Parker along with UR collaborators Professor Jannick Rolland (Institute of Optics) and Dr. Maiken Nedergaard (Department of Neurosurgery) were recipients of a 2018-19 University Research Award. These seed grants are given annually to promising high-risk projects. The title of their funded research project is "Brain Elastography with Optical Coherence Tomography." Project overview: The rapidly emerging field of brain elastography uses imaging systems to study the biomechanical properties of brain. Preliminary results demonstrate that this can be an important new diagnostic and research tool for neurosciences. This project proposes the highest resolution brain elastography studies using advanced Optical Coherence Tomography techniques on mouse models of normal and diseased brains that parallel human conditions. The goal is to answer the key scientific questions about the sensitivity of brain elastography to regional differences within the brain and to the progression of diseases.
You can read more about this year's URA award recipients here.
May 17, 2018
A paper co-authored by Professor Kevin Parker and graduate student Juvenal Ormachea, undergraduate student Hyunwoo Kim (UR Department of Biomedical Engineering), Dr. Michael Drage (UR Department of Pathology and Laboratory Medicine), and Doctor Zaegyoo Hah of Samsung Medison Co. Ltd. titled "The biomechanics of simple steatosis and steatohepatitis" will appear in the May 2018 issue of Physics in Medicine and Biology, and can be found here. The work presented in this article examined the rheological models that are capable of capturing the dominant viscoelastic behaviors associated with fat and inflammation in the liver, and quantified the resulting changes in shear wave speed and viscoelastic parameters. Theoretical results were shown to match measurements in phantoms and animal studies reported in the literature. These results are useful for better design of elastographic studies of fatty liver disease and steatohepatitis, potentially leading to improved diagnosis of these conditions.
April 26, 2018
A paper co-authored by Professor Kevin Parker and graduate student Juvenal Ormachea, along with Scott Will (graduate student in the UR Institute of Optics) and Dr. Zaegyoo Hah of Samsung Medison Co. Ltd. titled "Analysis of transient shear wave in lossy media" will appear in the July 2018 issue of Ultrasound in Medicine and Biology, and can be found here. The work presented in this article extends the analytical treatment of 2-D shear wave propagation in a biomaterial. The approach applies integral theorems relevant to the solution of the generalized Helmholtz equation, and does not depend on a specific rheological model of the tissue's viscoelastic properties.
April 6, 2018
Professor Parker was invited to present at a special session on ultrasonic imaging-based tissue characterization at the IEEE International Symposium on Biomedical Imaging, held 4-7 April 2018 in Washington, D.C. The presentation was titled "The H-scan sensitivity to scatterer diameter." The session was organized and chaired by Professor Roberto Lavarello of the Pontificia Universidad Catolica del Peru.
April 4, 2018
A paper co-authored by Professor Kevin Parker and Dr. Jeffrey Astheimer of HABICO, Inc. titled "Concentric layered Hermite scatterers" will appear in the May 2018 issue of Physics Letters A and can be found here. The article demonstrates that the necessary and sufficient conditions for supra-Rayleigh scattering power laws - in the case where the inhomogeneous material property conforms to a piecewise continuous constant function - can be stated simply by considering moments of the inhomogeneous function and its spatial transform. This development opens an additional path for construction and use of scatterers with unique power law behavior.
March 28, 2018
Congratulations to Juvenal Ormachea, graduate student in Professor Parker's Medical Imaging Research Lab, on receiving the New Investigator Honorable Mention award at the 2018 American Institute of Ultrasound in Medicine (AIUM) Annual Convention. Based on Juvenal's abstract submission titled "Reverberant Shear Wave Elastography: Implementation and Feasibility Studies," he was selected to participate in the New Investigator Award competition. Juvenal presented his work to the award committee and in a general session on March 26th and 27th at the convention in New York, NY. The committee evaluated over 100 new investigators, and selected 13 finalists. From those finalists, Juvenal's work was selected as one of the best and received the Honorable Mention award. Congratulations again to Juvenal on receiving this prestigious recognition at a conference of the top researchers and clinicians in the ultrasound community.
March 27, 2018
Professor Kevin Parker and PhD candidate Juvenal Ormachea attended and presented at the American Institute of Ultrasound in Medicine (AIUM) Convention held in New York, NY from 24-28 March 2018. Parker and Ormachea presented the following:
Shear Wave Speed Estimation Using Reverberant Shear Wave Fields: Implementation and Feasibility Studies
March 22, 2018
A paper co-authored by Professor Kevin Parker and PhD student Juvenal Ormachea titled "Shear wave speed estimation using reverberant shear wave fields: implementation and feasibility studies" will appear in the May 2018 issue of the Ultrasound in Medicine and Biology and can be found here. The paper is a collaboration Professor Benjamin Castaneda of the Pontificia Universidad Catolica del Peru (Lima, Peru). Recently, a new method was proposed for tissue stiffness estimation involving creation of a reverberant shear wave field propagating in all directions within the medium. These reverberant conditions lead to simple solutions, facile implementation, and rapid viscoelasticity estimation of local tissue. In this work, this new approach based on reverberant shear waves was evaluated and compared with another well-known elastography technique using two calibrated elastic and viscoelastic phantoms. Additionally, the clinical feasibility of this technique was analyzed by assessing shear wave speed in human liver and breast tissues, in vivo. The results indicate that it is possible to estimate the viscoelastic properties in each scanned medium.
March 9, 2018
Congratulations to Shujie Chen who successfully defended his PhD thesis titled “Enhanced Resolution Pulse-echo Imaging.” Shujie's public defense took place on Friday, March 9, 2018, immediately followed by a closed-door defense session. Shujie has been advised by Professor Kevin Parker. His PhD committee was chaired by Professor Stephen McAleavey (Biomedical Engineering); other committee members were Professor Marvin Doyley (Electrical & Computer Engineering) and Professor James Fienup (Institute of Optics). Again, congratulations to Shujie and many thanks for his hard work and significant contributions to Professor Parker's Medial Imaging Research Group. We wish him the best in his current position an Algorithm/DSP Engineer at Philips in Bothell, Washington.
February 7, 2018
A paper co-authored by Professor Kevin Parker and MD/PhD student Gary Ge titled "H-scan analysis of thyroid lesions" will appear in the January-March 2018 issue of the Journal of Medical Imaging and can be found here. The paper is a collaboration with Professor Roberto Lavarello of the Pontificia Universidad Catolica del Peru (Lima, Peru), and Drs. Joseph Pinto, Rosa Laimas, Jorge Guerrero, Himelda Chavez, and Claudia Salazar of Oncosalud (Lima, Peru). The article describes the application of the H-scan framework in a preliminary study of thyroid lesions to examine the H-scan outputs for three categories: normal thyroid, benign lesions, and cancerous lesions within a total group size of 46 patients. In addition, phantoms comprised of spherical scatterers are analyzed to establish independent reference values for comparison. The results demonstrate a small but significant difference in some measures of the H-scan channel outputs between the different groups.
February 1, 2018
PhD candidate Fernando Zvietcovich attended and presented at the SPIE Photonics West conference held in San Francisco, CA from 27 January - 1 February 2018. Zvietcovich presented the following: