Forthcoming

Forthcoming

Optical coherence tomography (OCT) provides imaging of living samples and even in vivo examination of cell structure and dynamics. The sectional imaging of OCT is achieved by direct visualization of raw data obtained in focused optical range finding. As a result, there is, in the OCT community, a widely held belief that there exists a trade-off between transverse resolution and the thickness of the volume that may be imaged with a fixed focal plane. In this talk I will show that a complete understanding of the physics of the problem leads to algorithms that provide a three-dimensional reconstruction of the object with a spatially invariant point-spread function for the system. The spatial resolution is everywhere equal to the best resolution in the raw data (in the focal plane). Thus the supposed trade-off between resolution and depth of imaging is eliminated as is any rationale for scanning the focus. Indeed, there is no need to actually form a focus or for the raw data to resemble the reconstructed object. Hardware requirements are significantly relaxed without comprising image quality. We refer to this new modality as interferometric synthetic aperture microscopy (ISAM). I will present the theoretical analysis, numerical simulations and experimental results.

The Biomedical Imaging Center, BIC, is a unit of the Beckman Institute. The Center traces its roots to the Biomedical Magnetic Resonance Laboratory founded at UIUC in 1985 by Professor Paul Lauterbur, 2003 winner of the Nobel Prize in Medicine for his pioneering work in magnetic resonance imaging, MRI.

BIC is home to a wide variety of research programs, providing facilities, equipment, and training for research on nuclear magnetic resonance imaging and spectroscopy. The Center's goal is to conduct research and develop imaging technologies that address questions ranging from the single cell to the complex inter-dependent systems underlying cognitive function. BIC is committed to the development of cutting edge techniques involving the integration of multiple imaging modalities including MRI, PET, SPECT, CT, ultrasound, optical imaging, eye-tracking, EEG and MEG.

BIC, which was recently relocated from a site on south campus to the basement of the Beckman Institute is home to three state-of-the-art MR imaging systems: a 3T human, head-only scanner, a 3T human whole-body scanner and a 14.1T micro-imager. In addition to these three MR scanners and thanks to a collaboration with Professors Bill O’Brien and Steve Boppart, BIC will soon house a new high-resolution, animal ultrasound system and a new Micro PET/SPECT/CT system.

Abstract 2:

According to the biased competition model of attention, attentional biasing is the remedy for competitive interactions among stimulus representations. Studies supporting this theory have always had the subject direct attention to a single item. We investigate whether attentional biasing is effective in reducing competition among multiple attended items. When multiple neighboring visual stimuli appear simultaneously, they interact in a mutually suppressive way; focusing attention on one of these stimuli eliminates or reduces these suppressive effects (Reynolds et al., 1999; Kastner et al. 1998). If attention is divided among all the stimuli processed within a RF, however, it should be unable to isolate the contribution of a single stimulus, and competitive interaction should consequently be unchanged. Our previous work (Scalf and Beck, submitted) confirms that multiple items produce more competition when attention is directed to multiple items, rather than to a single item. In the current experiment, we investigate whether attention directed to multiple items reduces competition among those items relative to conditions in which none of the items are attended. We presented subjects with five complex visual stimuli in an array centered in the upper right quadrant, along with a stream of digits, letters and symbols at fixation. We manipulated whether attention was applied to the stimuli by asking participants to monitor either for a color/shape/texture conjunction in any of the five locations or for an “a” at fixation. We manipulated the degree of competition among items by employing sequential (SEQ) and simultaneous (SIM) presentation conditions. In the SEQ condition, each stimulus was presented alone for 250 ms in one of the five locations. In the SIM condition, stimuli appeared together in all five locations for 250 ms. Integrated over time, the physical stimulation parameters in each of the five locations were identical under the two conditions. Competition, however, could take place only among the stimuli presented simultaneously (Kastner et al., 1998). We find robust competition among the objects (greater activation under sequential presentation than under simultaneous presentation) across attentional conditions. Although attention to the five items increased the overall activity evoked by the attended items in V4, this effect did not interact with presentation condition; that is, there was no evidence that attention to five items reduced competition relative to when the same items were unattended. Our data indicate that, when applied to multiple competing items simultaneously, attention is an ineffective remedy for competition for representation.

The field of micro-Computed Tomography (microCT) has changed dramatically since the speaker previously addressed the Forum (Feb. 2003). The first part of this talk reviews recent trends in instrumentation and in the type and distribution of published micro- and nanoCT studies. Second, several applications of tube and synchrotron-based microCT systems are used to illustrate some of the wide range of current research fields; these emphasize non-invasive multimode studies (specifically x-ray microbeam diffraction). The examples include: quantification of demineralization in tooth enamel, characterization of the tooth’s dentinoenamel junction, observation of microcracking in bone, measurement of spine fusion in rats and characterization of mineral formed in the Malpighian tubules (kidney analogs) of silkworms. Predictions of future micro- and nanoCT trends conclude the presentation.

Imaging and analysis over length scales down to sub-Ångström level is an integral component of materials science that is a key to understanding properties and performance of materials and devices. The Center for Microanalysis of Materials has a range of imaging techniques that are made available to researchers from campus, as well as outside academic and industrial scientists. The primary mode of access is self-used guided by professional staff. The overview will cover methods for chemical imaging of surfaces and depth profiling, including secondary ion mass spectrometry, x-ray photoelectron spectroscopy and Auger electron spectroscopy. A suite of four scanning electron microscopes permits high-resolution imaging, energy- and wavelength-dispersive x-ray mapping, electron back-scattered diffraction pattern mapping, cathodoluminance imaging. The CMM provides a wide range of transmission electron microscopy (TEM) techniques, including energy dispersive x-ray mapping, electron energy loss spectroscopy and imaging. The spherical aberration corrected scanning TEM provides 0.1 nm electron probe. Recent advances in spherical and chromatic aberration correction with the DOE-TEAM project will be reviewed. A collection of scanning probe microscopies provides quantitative information of the topography and physical properties of surfaces. The CMM has developed a unique combination of low-energy electron microscope/negative ion beam that allows studying the dynamics of surfaces under energetic atomic fluxes. The availability of a range of techniques with complementary capabilities is enabling an effective and successful materials research.

The ITG Visualization Laboratory, on the 4th floor of the Beckman Institute, is a resource for the entire UIUC campus. Open 24/7 to registered users, the lab provides high-end computing hardware, software, image-capture instrumentation, and related equipment to facilitate research utilizing imaging and visualization technology. This includes resources to support 2D/3D/4D image analysis and volumetric quantification, scientific visualization, 3D computer modeling and animation, ultra-high speed video, macro-photography, macro-video, video production, high-resolution 2D scanning, 3D object scanning, full-color 3D printing, research presentation imagery, and publication graphics. This talk is intended to provide and up to date overview of the Visualization Laboratory and outline how this resource lab fits into the mission of the Imaging Technology Group and the larger campus community.

Modern biology and medicine require advanced imaging tools. To meet the requirement, a number of new imaging techniques have been developed using known affinity agents such as RGD peptide as a proof of concept. To make these imaging technologies truly useful to researchers in biological and medical fields, one needs to develop imaging agents that are highly selective toward real targets in the researchers’ laboratory. Despite recent progress, designing those imaging agents based on a single class of molecules for a broad range of targets with high selectivity remains a significant challenge. Until today, antibodies are the main choice. Due to their large size, high costs and low stability, antibodies may not be suitable as imaging agents for many applications. In addition, antibodies are not effective against small molecular targets, targets too toxic to raise antibodies, or conditions not optimal for antibody functions. We have been able to use in vitro selection to obtain functional DNA (DNA with specific binding and enzymatic activities, also called DNAzymes and aptamers) that can bind both small and large molecular targets specifically, and used negative selection strategy to improve the selectivity. By labeling the resulting functional DNA with fluorophore/quencher, gold nanoparticles, quantum dots, or supermagnetic iron oxide nanoparticles, we have developed new classes of fluorescent, colorimetric and smart MRI contrast agents for a broad range of targets, with detection limit down to 11 ppt, and up to millions-fold selectivity. A novel approach of using an inactive variant of functional DNA to tune the concentration dynamic range to match those in the biological systems is also demonstrated. Recent results, including successful launch of functional DNA sensing products in the market in collaboration with ANDalyze, Inc. will be presented. [Juewen Liu, Zehui Cao and Yi Lu, Chem. Rev. 109, 1948–1998 (2009)]

The Imaging Technology Group runs two educational outreach projects, Bugscope and Virtual Microscope. Both provide free Web access to interactive microscopy on instruments ordinarily unavailable to grade-school students and small colleges. Bugscope allows educators to reserve 1-2 hours of time on a research-grade scanning electron microscope; they are able to investigate their own insect samples and converse with scientists in real time with just a web browser. The Virtual Microscope software mimics a microscope's controls and enables users to explore specimens on-demand by loading massive pre-collected data-sets from a collection of 90 specimens. This presentation will briefly cover lessons learned over the more than 10 continuous years Bugscope has been active. It will focus on the current state of the Bugscope project and recent collaboration with the London Natural History Museum to expand upon and contribute to the Virtual Microscope project.

Transcatheter and percutaneous liver-directed approaches are widely used for the treatment of liver tumors. These therapies include transcatheter arterial chemoembolization (TACE), radioembolization, and percutaneous ablation. Intra-procedural imaging guidance may be critical to optimize outcomes. During the talk I will describe our recent pre-clinical and translational work focused upon the development and validation of new magnetic resonance imaging methods for intra-procedural monitoring of tumor perfusion changes during TACE, depiction of intra-hepatic radioembolization microsphere delivery, and monitoring tissue ablation zones during percutaneous irreversible electroporation procedures.