SMARTech Community: Undergraduate Research Opportunities Program (UROP)

Characterizing Single Ventricle Patient-Specific Anatomy Using Segmentation of MRI and 3D Reconstruction to Aid Surgical Planning

Thu, 31 Jul 2008 22:58:59 GMT

Title: Characterizing Single Ventricle Patient-Specific Anatomy Using Segmentation of MRI and 3D Reconstruction to Aid Surgical Planning

Authors: Jayaprakash, Gopinath

Abstract: Single ventricle congenital heart defects occur 2 per every 1000 live births in the USA. In these cases, cyanosis occurs due to the mixing of venous deoxygenated blood and oxygenated blood from the lungs. These defects are surgically treated by the total cavo-pulmonary connection (TCPC), where the superior and inferior vena cavae are connected to the pulmonary arteries routing the systemic venous return directly to the lungs. However, this Fontan repair results in high energy losses and therefore the optimization of this connection prior to the surgery could significantly improve post-operative performance. In this paper, the in-house segmentation and 3D reconstruction scheme is used in the following studies. First, 3D geometrical analysis of the TCPCs is used to determine the advantages and disadvantages of two commonly performed TCPC palliations intra-atrial and extra-cardiac configurations. Then, a surgical planning outline is proposed with segmentation of pre and post surgical Magnetic Resonance Imaging (MRI) data followed by the 3D reconstruction with emphasis on extracting surrounding vessels and structures. A pediatric surgeon performs a virtual surgery on the reconstruction of the patient s pre-Fontan anatomy prior to the actual surgery. A segmentation of the heart, aorta and surrounding vessels superimposed with the Glenn, when used with the SURGEM® tool, simulates the actual Fontan operation. This outline allows the surgeon to envision numerous scenarios of possible surgical options, and accordingly to predict the post operative procedures. The segmentation tool is improved upon to increase the accuracy and efficiency of the process and enhance the quality of the anatomical reconstructions.

Design and development of a novel compact soft-surface structure for performance improvement and size reduction of a microstrip Yagi array antenna

Sun, 04 May 2008 22:58:59 GMT

Title: Design and development of a novel compact soft-surface structure for performance improvement and size reduction of a microstrip Yagi array antenna

Authors: Thai, Trang Thuy

Abstract: An new antenna structure based on a microstrip Yagi array antenna and a soft surface (SS) ring is designed and developed, which enables a highly directional gain in addition to an improved front-to-back (F/B) ratio of more than 20 dB. The SS ring is shown to be capable of greatly improving the performance while miniaturizing the design s size by half. The implementation of the SS ring to a microstrip Yagi array antenna is demonstrated for different ground sizes to verify its functionality in suppressing surface waves, showing that an improvement of at least 3 dB in the F/B ratio can be obtained. The design is investigated at the center frequency of 5.8 GHz, however, the structure can be easily scaled to other frequency ranges. A parametric analysis is performed to give insight into the operational mechanism of the SS ring and on the critical dimensions that affect the SS structure surrounding the antenna array. In addition, measurements are presented to validate the results obtained via simulation. The principles established in this paper are applicable to other planar antenna designs.

Sustained Delivery of Thermally Stabilized chABC by Lipid Microtubules

Sun, 04 May 2008 22:58:59 GMT

Title: Sustained Delivery of Thermally Stabilized chABC by Lipid Microtubules

Authors: Kumar, Nathan

Abstract: Our knowledge of spinal cord injury repair is broadening with the developing technology for nerve regeneration and drug delivery. In this paper we discuss the current capabilities for spinal cord repair as well as those that are in development. We develop protocols for determining the thermal stability of chondroitinase ABCI and its ability to be implanted into a microtubule-hydrogel drug delivery vehicle as well as the release profile that results from this implantation. After the use of sodium dodecyl electrophoresis, we determined that the disaccharide trehalose has the capacity to thermally stabilize our therapeutic enzyme in vitro. We also determined that the microtubules are effective for sustaining the release of our enzyme while the hydrogel is effective for localizing its effects. The deactivation profile was experimentally quantified to allow for complete diffusion of our enzyme over the course of a two-week implantation. Our thermally stabilized enzyme and drug delivery system can be used for the purpose of facilitating nerve regeneration at the site of an injury.

Visual and Auditory Velocity Perception and Multimodal Illusions

Sun, 04 May 2008 22:58:59 GMT

Title: Visual and Auditory Velocity Perception and Multimodal Illusions

Authors: Gasaway, Katherine S.

Abstract: Although ambiguous and conflicting sensory information from different sensory modalities is common, people seldom experience perceptual ambiguities or conflict between senses. Just as the retinal nerve blind spot is filled in and seldom seen, conflicting or otherwise confusing sensory information is resolved in favor of the most appropriate modality, eliminating the confusion from conscious experience. The ventriloquism effect and auditory driving are two examples of perceptual phenomena arising from this sensory override. This research explores the hypothesis that velocity perception is subject to the same effects. Subjects were presented with two bimodal (auditory-visual) stimulus pairs and asked to determine which of the visual stimuli was moving faster. In a V2A2/V2A1 condition, participants responded significantly more frequently that the first visual stimulus was faster than in any non-target condition. This effect was not found for V2A2/V2A3 trials.