Functional- and molecular- tomography of glowing mice and blushing brains
( Imaging and Visualisation Series )
Dr Joseph Culver, Washington University School of Medicine
Date and time: Friday 15th May 2009 at 13:00
Location: UG40, School of Computer Science
Host: Professor Ela Claridge
Functional- and molecular- tomography of glowing mice and blushing brains
Our lab explores ways of leveraging non-invasive optical measurements for both functional- and molecular- biological imaging. Optical approaches to small animal in vivo molecular imaging provide high sensitivity, stable non-radioactive probes, and an extensive array of functional reporting strategies. For example optical methods can report on large variety of protein activities, and reveal cancer progression by imaging events such as angiogenesis and metastases. However, quantitative whole body assays in live intact animals remain elusive. While bioluminescence and fluorescence reflectance planar imagers provide quick assessments, quantitative localization is lacking due to strong depth dependence in sensitivity, masking of buried targets by superficial tissues, and poor resolution. We are developing a small animal fluorescence tomography (FT) platform to address these imaging challenges. With a fast scanning FT prototype we have begun tackling the practical challenges of providing flexible- and dense- spatial sampling, whole body field-of-view and reasonable scan times (minutes). Currently we are extending our FT platform into the ultrafast time domain (~1ns) to improve a number of image quality metrics and further expand our biological reporting strategies.
For application in humans we are developing a portable device for functional neuroimaging. Diffuse optical tomography (DOT) is well-suited for several novel situations including studies of human child development that would benefit from enriched ecological environments for a wider range of behavioral paradigms. However, successful DOT in humans is challenging due to the concurrent requirements of high-dynamic range, low crosstalk, high channel counts, and sufficient temporal resolution. Hence, most optical imaging of human brain activity is performed using a topography approach with relatively sparse imaging arrays. Tomographic approaches offer benefits including volumetric localization and better discrimination of the functional brain signals from the background that are crucial to establishing DOT as a standard brain-mapping tool. We have developed new instrumentation with improved performance characteristics that permits use of high-density DOT arrays. Current studies in the adult visual cortex demonstrate the capability to distinguish activation sites separated by ~ 1cm. Our goal is to develop DOT for mapping activity throughout the outer surface of the brain with sub-centimeter resolution.