Photoacoustic Imaging for Detection and Monitoring of Metal Syringe Needles

Life Sciences : Medical Devices

Available for licensing


  • Stanislav Emelianov, Ph.D. , Biomedical Engineering
  • Jimmy Su , Biomedical Engineering
  • Bo Wang, M.S. , Biomedical Engineering
  • Wolfgang Frey , Biomedical Engineering
  • Andrei Karpiouk, Ph.D. , Biomedical Engineering
  • Yun-Sheng Chen , Electrical and Computer Engineering

Background/unmet need

The ability to accurately image and localize metal objects within a patient’s body is needed to detect foreign metal objects or diagnose and monitor previously implanted metal devices.

Currently, ultrasound-guided imaging provides physicians with a method to monitor the location of foreign bodies, such as metal needles, stents, and other implants or aspirations; however, this method is highly directionally-dependent based on the object’s position to the ultrasound transducer. Objects such as reflective needles are often rendered invisible in the ultrasound image because of the transmitted ultrasound echo is reflected off the metal surface and away from the transducer. Instead, clinicians are trained to identify the ultrasound shadow created by an object in order to determine the object’s position, but in only identifying the shadow, the exact position of the needle is compromised.

Though clinical devices exist to guide the needle relative to the ultrasound transducer, these devices limit the degrees of freedom that the imaging transducer can be moved; instead, most clinicians prefer to employ a freehand technique during imaging. Furthermore, imaging contrast between the metal device and the background can be limited in the presence of highly acoustically scattering tissue.

Invention Description

Instead of relying on the ultrasound signal during imaging, photoacoustic (or optoacoustic) imaging allows for clearer imaging of foreign objects within a patient. Dr. Emelianov, from the University of Texas at Austin, presents a method for utilizing photoacoustic imaging for accurately tracking the position of clinical needle interventions and other foreign objects inserted into the human body. Because the photoacoustic signal propagates omni-directionally and only from highly absorbing objects, an ultrasound transducer cannot detect the signal and render the needle with high contrast and visibility.

Photoacoustic shares the same ultrasound transducer for signal detection; therefore, the concurrent performance of both imaging methods allows for the production of automatically co-registered images. As opposed to ultrasound imaging alone, the combination of a pulsed laser with clinical ultrasound produces contrast according to the optical absorption of the objects being imaged, resulting in better visibility of an imaged object with respect to its the tissue background.

In addition to needle tracking, the technology gives the information about the surrounding tissue environment. Combining photoacoustic and optoacoustic imaging technologies enables clinicians to determine the tissue composition surrounding an inserted needle or metal object in a human body. This tissue differentiation occurs due to variations in optical absorption rates of different tissues. For example, a needle inserted into muscle will have a very different signal amplitude than the same needle inserted into fat, a fluid pocket, or cancerous tumor.


  • Photoacoustic imaging allows for visualization of needles inserted in tissue
  • Ability to image highly reflective metal objects
  • Photoacoustic image shows high contrast and high resolution
  • Real-time imaging with ultrasound
  • Ability to visualize presence of blood vessels and other optical absorbers in tissue
  • Distinguishes between different types of tissues experiencing needle insertion or containing a metal object in the body

Market potential/applications

The U.S. medical-imaging market--including ultrasound, magnetic resonance imaging (MRI), radiography and mammography, and computed tomography (CT)--will be worth an estimated $11.4 billion by 2012, according to a new report by BCC Research, Medical Imaging: Equipment and Related Products. The third-largest segment, ultrasound equipment, is currently valued at $1.6 billion and is expected to grow with a CAGR of 6.9 percent to $2.3 billion in 2012.

Development Stage

Lab/bench prototype