Parametric Image

About: Parametric Image is a research topic. Over the lifetime, 311 publications have been published within this topic receiving 6095 citations.

Imaging through Diffusing Media by Image Parametric Amplification

Abstract: Imaging through thick diffusing media requires selection of the least scattered light, because ballistic light is only transmitted up to a few millimeters. Hence, temporal gating, i.e. isolation of the front part of a femto or a picosecond pulse appears as a promising tool to form images of objects embedded in thick media, like tumors in human breast. We have used parametric image amplification to obtain images with a time gate duration of about 20 ps. At first, we used latex beads solutions, whose diffusing properties are well known, to characterize the method and its dynamic range for selection of the ballistic light. In a second step, objects embedded in biological tissues, like chicken meat, were imaged. The best results have been obtained by forming the image without lenses, by exploiting the fact that the idler is phase-conjugated with respect to the signal in the transverse directions, while it propagates forward. A 1 cm3 piece of liver embedded in a 4 cm thick chicken breast tissue has been detected.

Observation of quantum noise correlations in parametric image amplification

Abstract: There has recently been increased interest in the application of squeezed light to phenomena in the spatial domain. In particular, it was shown that spatially broadband squeezed light can be used to image faint objects with subshot noise sensitivity.’ Since an optical parametric amplifier (OPA) generates correlated photons that are spatially broadband, it is an ideal process for the initial demonstration of quantum correlations in image amplification. Quantum-noise reduction of more than 6 dB has previously been achieved by use of twin beams of light generated by a traveling-wave 0PA.Z Also, parametric amplification has been shown to have practical applications in timegated image r e~overy .~ ,~ An example is the amplification of ballistic photons through turbid media for biomedical imaging.5 Here we report what we believe to be the first observation of quantum noise correlations between the spatial frequencies of a parametrically amplified image and the generated conjugate image. As shown in Fig. la, an object is placed in the signal (1064 nm) path and imaged via a X 1 telescope into the OPA. The image inside the OPA is formed by light traveling at many different spatial frequencies. Since the pump beam (532 nm) is aligned on axis, we can assume it to be a plane wave at zero spatial frequency. Because the OPA is spatially broadband, a range of spatial frequencies of the image are amplified and, additionally, an idler image with similar spatial frequencies is generSoliton Energy (pJ)

Effect of measurement uncertainty on region of interest based and parametric binding potential estimates for the high resolution research tomograph (HRRT)

Abstract: High resolution Positron Emission Tomography (PET) imaging leads to very small pixel sizes. Generally the increase in resolution is not paralleled by a corresponding increase in sensitivity which may cause the count density per voxel to be low. Here we are exploring how the statistical quality of the data acquired with the high resolution research tomograph (HRRT) influences the accuracy of the determination of the binding potential (BP) for typical human studies performed with 11middotC-raclopride. Susceptibility to noise was tested for 3 modelling approaches: the Logan graphical model, the simplified reference tissue method (RTM) and the delayed ratio method (DRM). For each approach BP was calculated on a region of interest (ROI) and voxel basis (parametric maps). Using a method based on experimentally defined replicas of time activity curves (TACs) representative of those obtained in human scans we found that for this tracer the contribution of the statistical noise to the BP determination is ~ 5-8 % when the TACs are evaluated on an ROI basis (either ROI TACs used as input, or ROI placed on the BP parametric image) and 9-12 % when calculated on a single pixel basis. The Logan approach was found to suffer from a considerable bias due to statistical noise when the BP was calculated on a single pixel basis, while RTM and DRM showed no such bias. Overall, for this tracer and these scanning conditions the RTM proved to be the least sensitive to statistical noise in the data.

Characterization of Breast Masses Using a New Method of Ultrasound Contrast Agent Imaging in 3D Mapping of Vascular Anomalies

Abstract: : Doppler ultrasound and other imaging modalities have been used to assess characteristics of vasculature associated with malignant breast masses. 3D contrast refill imaging should help visualize slow-flow in small neo-vasculature associated with these masses. The dual-transducer method proposed should provide vascular mapping while minimizing acquisition time, the major limitation of techniques such as interval-imaging (I-I) and real-time (RT) imaging. Phantom tube-flow studies from Y2 were further quantified. A phantom kidney model initially tested in Y2 has been extensively studied and compared to I-I and RT methods. Image volumes reconstructed using the dual-transducer method displayed remarkable spatial detail. After accounting for contrast decay, mean transit times (MTTs) for image planes derived from reconstructed image volumes were consistent (p<0.05) with corresponding single I-I and RT scans. In addition, the development of a parametric image display scheme has been undertaken. Raw images highlighting differences in MTT throughout the model have been generated, and refinements to parametric calculations are currently underway. Limitations of the clinical ultrasound machine were still problematic during Y3, and no patient data has been acquired. We hope to conduct a slightly abridged clinical phase during a no-cost extension period. Y3 results are presented here.