Jami Shepherd

Jami Shepherd
University of Auckland · Department of Physics

BSc Physics, MSc Mechanical Engineering, PhD Physics

About

21
Publications
1,673
Reads
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161
Citations
Introduction
Jami Shepherd (Johnson) is a Research Fellow in the Department of Physics at the University of Auckland. She is interested in wave propagation and photoacoustic, ultrasonic, and laser-ultrasonic imaging for biomedical applications.
Additional affiliations
October 2013 - present
University of Auckland
Position
  • PhD Student
August 2011 - May 2013
Boise State University
Position
  • Research Assistant
June 2008 - May 2011
Bethel University (Minnesota)
Position
  • Research Assistant

Publications

Publications (21)
Article
Full-text available
Intraosseous blood circulation is thought to have a critical role in bone growth and remodeling, fracture healing, and bone disorders. However, it is rarely considered in clinical practice due to the absence of a suitable non‐invasive in vivo measurement technique. In this work, we assessed blood perfusion in tibial cortical bone simultaneously wit...
Preprint
Full-text available
Intraosseous blood circulation is thought to have a critical role in bone growth and remodeling, fracture healing, and bone disorders. However, it is rarely considered in clinical practice due to the absence of a suitable non-invasive in vivo measurement technique. In this work, we assessed blood perfusion in tibial cortical bone simultaneously wit...
Article
Photoacoustic (PA) imaging is an emerging modality, which combines the high optical absorption contrast of biological chromophores with centimeter imaging depths and sub-millimeter resolution of ultrasonic (US) waves. However, PA imaging through cortical bone remains an unmet challenge. Cortical bone is an anisotropic medium, which is not accuratel...
Article
Full-text available
Photoacoustic (PA) imaging may be advantageous as a safe, non-invasive imaging modality to image the carotid artery. However, calcification that accompanies atherosclerotic plaque is difficult to detect with PA due to the non-distinct optical absorption spectrum of hydroxyapatite. We propose reflection-mode all-optical laser-ultrasound (LUS) imagin...
Article
Full-text available
From acoustics to medical imaging and seismology, one strives to make inferences about the structure of complex media from acoustic wave observations. This study proposes a solution that is derived from the multidimensional Marchenko equation, to learn about the acoustic source distribution inside a volume, given a set of observations outside the v...
Conference Paper
Arterial tissue imaging and characterization is important for disease diagnosis, treatment planning and monitoring, and research into disease processes. The high optical contrast of photoacoustic imaging can distinguish molecules with unique optical spectra from surrounding arterial tissue, while ultrasound is sensitive to variations in acoustic pr...
Article
Full-text available
Biomedical imaging systems incorporating both photoacoustic (PA) and ultrasound capabilities are of interest for obtaining optical and acoustic properties deep in tissue. While most dual-modality systems utilize piezoelectric transducers, all-optical systems can obtain broadband high-resolution data with hands-free operation. Previously described r...
Thesis
Elastic waves are used across a broad spectrum in medicine to non-invasively probe and image tissues up to centimeters deep. Ultrasonic (US) imaging is the most well-known modality used to image acoustic density and velocity contrasts. US is useful for imaging overall structure in tissue, however, acoustic contrasts are relatively low in biological...
Poster
Full-text available
Biomedical image reconstruction using photoacoustic (PA) and -- more recently -- laser-ultrasound (LU) data is an active area of investigation. Previously, we demonstrated that a framework for LU image reconstruction can be developed based on reverse-time migration (RTM), an approach originally developed for seismic imaging. When combined with a mu...
Conference Paper
Conventional contacting transducers are highly sensitive and readily available for ultrasonic and photoacoustic imaging. On the other hand, optical detection can be advantageous when a small sensor footprint, large bandwidth and no contact are essential. However, most optical methods utilizing interferometry or Doppler vibrometry rely on the reflec...
Article
Conventional contacting transducers for ultrasonic wave detection are highly sensitive and tuned for real-time imaging with fixed array geometries. However, optical detection provides an alternative to contacting transducers when a small sensor footprint, a large frequency bandwidth, or non-contacting detection is required. Typical optical detectio...
Conference Paper
We propose a new reconstruction algorithm for photoacoustic and laser-ultrasound imaging based on reverse time migration (RTM), a time reversal imaging algorithm originally developed for exploration seismology. RTM inherently handles strong velocity heterogeneity and complex propagation paths. A successful RTM analysis with appropriate handling of...
Article
In modern laboratories, software can drive the full experimental process from data acquisition to storage, processing, and analysis. The automation of laboratory data acquisition is an important consideration for every laboratory. When implementing a laboratory automation scheme, important parameters include its reliability, time to implement, adap...
Article
Multi-channel photo-acoustic and laser ultrasonic waves are used to sense the characteristics of proxies for healthy and diseased vessels. The acquisition system is non-contacting and non-invasive with a pulsed laser source and a laser vibrometer detector. As the wave signatures of our targets are typically low in amplitude, we exploit multi-channe...

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