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Pierre Mourad

Senior Principal Physicist

Adjunct Associate Professor, Bioengineering and Associate Professor, Neurological Surgery

Email

pierre@apl.washington.edu

Phone

206-543-6921

Research Interests

Bioacoustics, Fluid Dynamics, Applied Mathematics

Biosketch

Dr. Mourad has conducted and published basic and applied research in oceanography, atmospheric sciences, sonoluminescence, arctic and ocean acoustics, acoustic holography, and medical acoustics. The latter has been his emphasis for the great part of the last decade.

He has generated more than twenty invention disclosures at the University of Washington and is an inventor on three issued patents and another thirteen patent applications, all having to do with means of diagnosing or treating various diseases and disorders. Much of his research is collaborative in nature, residing as it does at the interface of physics and medicine. Some of that research has motivated industrial interactions. His research on novel means of facilitating drug delivery has been incorporated into two recent startup companies %u2013 Ratner Biomedical Group and PhaseRx. Dr. Mourad's research on a novel power toothbrush that also uses ultrasound resides in Ultreo, Inc., a company he co-founded. Finally, he co-founded Allez PhysiOnix, Ltd. based on his research on monitoring intracranial pressure non-invasively, automating ultrasound Doppler systems, and improving physician%u2019s ability to localize painful tissues and organs.

He holds an appointment as Associate Professor in the UW Departments of Bioengineering, Neurological Surgery, and Pediatric Dentistry. Dr. Mourad and has been with APL-UW since 1988.

Education

B.A. Mathematics, Rutgers University, 1980

M.S. Applied Mathematics, University of Washington, 1982

Ph.D. Applied Mathematics, University of Washington, 1987

Publications

2000-present and while at APL-UW

Mixture models for estimating maximum blood flow velocity

Marzban, C., G. Wenxiao, and P.D. Mourad, "Mixture models for estimating maximum blood flow velocity," J. Ultrasound Med., 35, 93-101, doi:10.7863/ultra.14.05069, 2016.

More Info

1 Jan 2016



Objectives—A gaussian mixture model (GMM) was recently developed for estimating the probability density function of blood flow velocity measured with transcranial Doppler ultrasound data. In turn, the quantiles of the probability density function allow one to construct estimators of the “maximum” blood flow velocity. However, GMMs assume gaussianity, a feature that is not omnipresent in observed data. The objective of this work was to develop mixture models that do not invoke the gaussian assumption.

Methods—Here, GMMs were extended to a skewed GMM and a nongaussian kernel mixture model. All models were developed on data from 59 patients with closed head injuries from multiple hospitals in the United States, with ages ranging from 13 to 81 years and Glasgow Coma Scale scores ranging from 3 to 11. The models were assessed in terms of the log likelihood (a goodness-of-fit measure) and via visual comparison with the underlying spectrograms.

Results—Among the models examined, the skewed GMM showed a significantly (P< .05) higher log likelihood for 56 of the 59 patients and produced maximum flow velocity estimates consistent with the observed spectrograms for all patients. Kernel mixture models are generally less “robust” in that their quality is inconsistent across patients.

Conclusions—Among the models examined, it was found that the skewed GMM provided a better model of the data both in terms of the quality of the fit and in terms of visual comparison of the underlying spectrogram and the estimated maximum blood flow velocity. Nongaussian mixture models have potential for even higher-quality assessment of blood flow, but further development is called for.

Digital drug delivery: On-off ultrasound controlled antibiotic release from coated matrices with negligible background leaching

Noble, M.L., P.D. Mourad, and B.D. Ratner, "Digital drug delivery: On-off ultrasound controlled antibiotic release from coated matrices with negligible background leaching," Biomater. Sci., 2, 893-902, doi:10.1039/C3BM60203F, 2014.

More Info

1 Jun 2014

Hydrogels such as crosslinked poly(2-hydroxyethyl methacrylate) (pHEMA) have been used extensively in controlled release drug delivery systems. Our previous work demonstrated an ultrasound (US)-responsive system based on pHEMA coated with a self-assembled multilayer of C12–C18 methylene chains. The resulting coating was predominantly crystalline and relatively impermeable, forming an US-activated switch that controlled drug release on-demand, and kept the drug within the matrix in the absence of US. The device, as developed did, however, show a low background drug-leaching rate independent of US irradiation. For some applications, it is desirable to have very low or zero background release rates. This was achieved here by a combination of new processing steps, and by co-polymerizing HEMA with a relatively hydrophobic monomer, hydroxypropyl methacrylate (HPMA). These advances produced systems with undetectable ciprofloxacin background release rates that are capable of US-facilitated drug release — up to 14-fold increases relative to controls both before and after US exposure. In addition, these observations are consistent with the hypothesis that US-mediated disorganization of the coating allows a transient flux of water into the matrix where its interaction with bound and dissolved drug facilitates its movement both within and out of the matrix.

Mice exposed to diagnostic ultrasound in utero are less social and more active in social situations relative to controls

McClintic, A.M., B.H. King, S.J. Webb, and P.D. Mourad, "Mice exposed to diagnostic ultrasound in utero are less social and more active in social situations relative to controls," Autism Res., 7, 295-304, doi:10.1002/aur.1349, 2014.

More Info

1 Jun 2014

Clinical use of diagnostic ultrasound imaging during pregnancy has a long history of safety and diagnostic utility, as supported by numerous human case reports and epidemiological studies. However, there exist in vivo studies linking large but clinically relevant doses of ultrasound applied to mouse fetuses in utero to altered learning, memory, and neuroanatomy of those mice. Also, there exists a well-documented significant increase in the likelihood of non-right-handedness in boys exposed to diagnostic ultrasound in utero, potentially relevant given the increased prevalence of autism in males, and reports of excess non-right-handedness in this population. Motivated by these observations, we applied 30 minutes of diagnostic ultrasound to pregnant mice at embryonic day 14.5 and assayed the social behavior of their male pups 3 weeks after their birth. The ultrasound-exposed pups were significantly (P < 0.01) less interested in social interaction than sham-exposed pups in a three-chamber sociability test. In addition, they demonstrated significantly (P < 0.05) more activity relative to the sham-exposed pups, but only in the presence of an unfamiliar mouse. These results suggest that fetal exposure to diagnostic ultrasound applied in utero can alter typical social behaviors in young mice that may be relevant for autism. There exist meaningful differences between the exposure of diagnostic ultrasound to mice versus humans that require further exploration before this work can usefully inform clinical practice. Future work should address these differences as well as clarify the extent, mechanisms, and functional effects of diagnostic ultrasound's interaction with the developing brain.

More Publications

Inventions

Methods and systems for assessing a burn injury

The present invention provides methods, software, and systems for assessing a burn injury.

Patent Number: 9,295,402

Hassan Arbab, Antao Chen, Dale Winebrenner, Trevor Dickey, Pierre Mourad, Matthew Klein

Patent

29 Mar 2016

Device and Methods for Targeting of Transcranial Ultrasound Neuromodulation by Automated Transcranial Doppler Imaging

Record of Invention Number: 46512

Pierre Mourad

Disclosure

17 May 2013

Combining Ultrasound and Light to Monitor Brain Perfusion and Oxygen

Record of Invention Number: 46488

Pierre Mourad

Disclosure

26 Apr 2013

More Inventions

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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