Article

Photoacoustic Tomography of Foreign Bodies in Soft Biological Tissue

Department of Biomedical Engineering, Optical Imaging Laboratory, Washington University, St Louis, Missouri 63130, USA.
Journal of Biomedical Optics (Impact Factor: 2.75). 04/2011; 16(4):046017. DOI: 10.1117/1.3569613
Source: PubMed

ABSTRACT In detecting small foreign bodies in soft biological tissue, ultrasound imaging suffers from poor sensitivity (52.6%) and specificity (47.2%). Hence, alternative imaging methods are needed. Photoacoustic (PA) imaging takes advantage of strong optical absorption contrast and high ultrasonic resolution. A PA imaging system is employed to detect foreign bodies in biological tissues. To achieve deep penetration, we use near-infrared light ranging from 750 to 800 nm and a 5-MHz spherically focused ultrasonic transducer. PA images were obtained from various targets including glass, wood, cloth, plastic, and metal embedded more than 1 cm deep in chicken tissue. The locations and sizes of the targets from the PA images agreed well with those of the actual samples. Spectroscopic PA imaging was also performed on the objects. These results suggest that PA imaging can potentially be a useful intraoperative imaging tool to identify foreign bodies.

Download full-text

Full-text

Available from: Manojit Pramanik, Apr 03, 2014
0 Followers
 · 
114 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Since the introduction of intravascular, catheter-based invasive imaging and diagnostic tools in the catheterization laboratories two decades ago, the functional assessment of angiographically moderate or ambiguous lesions by fractional flow reserve measurements represents the established standard of care today. Likewise, intravascular ultrasound (IVUS) is widely accepted to guide treatment strategy in complex lesions, such as long or left main stem lesions. Developments are driven by the clinical interest to optimize treatment, prevent periprocedural complications, understand treatment failure and understand progression of atherosclerosis. As a result, a variety of devices are now clinically available that enable detection and monitoring of specific plaque features over time, such as the presence of necrotic core by IVUS-VH, a lipid-core plaque by near infrared (NIR) spectroscopy or a thin fibrous cap atheroma by optical coherence tomography (OCT). As the physical boundaries for both light and sound are different, these imaging technologies offer different advantages and limitations. Light-based technologies offer unparalleled high image resolution (OCT) or unparalleled high sensitivity and specificity for distinct plaque components (NIR spectroscopy), whereas conventional IVUS offers a much better tissue penetration. From a clinical perspective, both types of information are valuable. Ideally, this information should easily and in real time be available in the catheterization laboratory, consisting of co-registered datasets gained during a single catheter pullback. On this background, a combined NIR spectroscopy and IVUS catheter has recently been introduced for clinical use. The article discusses the potential and limitations of these different technologies. They may allow advanced coronary plaque diagnosis in a fast, accurate, reliable, user- and patient-friendly manner and, as such, can help to improve clinical practice today and therapeutic options in the future.
    Journal of Cardiovascular Medicine 06/2011; 12(8):562-70. DOI:10.2459/JCM.0b013e3283492b5a · 1.51 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Optoacoustic imaging is an emerging medical technology that uniquely combines the absorption contrast of optical imaging and the penetration depth of ultrasound. While it is not currently employed as a clinical imaging modality, the results of current research strongly support the use of optoacoustic-based methods in medical imaging. One such application is the diagnosis of the presence of soft tissue foreign bodies. Because many radiolucent foreign bodies have sufficient contrast for imaging in the optical domain, laser-induced optoacoustic imaging could be advantageous for the detection of such objects. Common foreign bodies have been scanned over a range of visible and near infrared wavelengths by using an optoacoustic method to obtain the spectroscopic properties of the materials commonly associated with these foreign bodies. The derived optical absorption spectra compared quite closely to the absorption spectra generated when using a conventional spectrophotometer. By using the probe-beam deflection technique, a novel, pressure-wave detection method, we successfully generated optoacoustic spectroscopic plots of a wooden foreign body embedded in a tissue phantom, which closely resembled the spectrum of the same object obtained in isolation. A practical application of such spectra is to assemble a library of spectroscopic data for radiolucent materials, from which specific characteristic wavelengths can be selected for use in optimizing imaging instrumentation and provide a basis for the identification of the material properties of particular foreign bodies.
    Applied Spectroscopy 01/2013; 67(1):22-8. DOI:10.1366/11-06562 · 2.01 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, an inductive proximity sensor with a longer range when compared to its diameter is presented. This sensor is intended to guide doctors, while performing surgery to remove metal shrapnel from victims of bomb blasts, gun fire, land mines etc. Presently doctors rely on imaging systems to locate shrapnel in the victim's body before surgery. Effectiveness of surgery and recovery solely depends on the doctors' skill to trace the shrapnel. In some cases the shrapnel may be visible in the images, but it may be untraceable during surgery. So in such cases, an inductive proximity sensor which is small enough to be introduced into the victim's body and can direct the recovery tool effectively to the exact location of the shrapnel, during the surgery, will be very useful to the doctor. Such a sensor, along with its details and experimental results are presented in this paper. This sensor works on a new comparison based method to detect tiny targets, as the detector size is a constraint here. The sensor can detect shrapnel materials such as steel, brass and Aluminium. A smaller, modified version of this sensor is also presented in the paper, along with a study of the effect of body tissues on sensor performance.
    Instrumentation and Measurement Technology Conference (I2MTC), 2013 IEEE International; 01/2013