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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Measurement of physiological parameters with echo-planar imaging

Freeman, Alan John January 1995 (has links)
No description available.
2

Radiofrequency Coils for Faster and Quieter MR Imaging on a Neonatal MR System

Ireland, Christopher M. 15 October 2020 (has links)
No description available.
3

Design of Radiofrequency Coils for Magnetic Resonance Imaging Applications: A Computational Electromagnetic Approach

IBrahim, Tamer S. 29 January 2003 (has links)
No description available.
4

Achieving Invisible Balance: Utilizing Novel Elliptical Traps for Improved Radiofrequency Coil Thermodynamic Stability, Minimized Field Distortion, and Common-Mode Current Suppression

Jana Vincent (10711377) 29 April 2021 (has links)
<p>Advances in Magnetic Resonance Imaging (MRI) have been made possible through increased field strengths and innovations in radiofrequency (RF) coils. With increasing field strengths, unique challenges are presented in RF coil development, namely the suppression of common-mode currents present along the shields of the cabling that connect the RF coil to the MR scanner. These currents can lead to coupling with the coil, resulting in a reduction of coil sensitivity and signal-to-noise ratio. These currents can induce local electric fields that beyond a certain level can exceed SAR limits and even cause patient burns. Several cable trap designs exist to help address this problem; however, many of the existing designs, such as bazooka cable traps, are rigid and bulky. This leads to increased overall coil weight and impedes the flexibility of the cable. Improving upon these designs, a small, 3D-printed, lightweight elliptical cable trap is presented. The unique geometry makes it invisible to the MR scanner while maintaining significant mutual inductance that can produce up to 380 Ω on the cable. These structures were wrapped with stranded wire containing four breaks for tuning capacitors. 60 of these elliptical cable traps were placed along the length of a 139-cm cable, replacing the standard 4 bazooka cable traps. The results of B<sub>1</sub> distortion and heating tests showed that these elliptical baluns improve RF coil thermodynamic stability, produce less B<sub>1</sub> distortion, and reduce overall coil weight and bulk compared to a cable with four bazooka traps. </p>
5

Stretching the Boundaries of Radiofrequency Coil Design For MRI: Innovations in Lightweight, Flexible, and Stretchable Designs for Enhanced Patient Comfort and Image Quality

Jana Vincent (10711377) 29 April 2021 (has links)
<p>There have been several advancements in radiofrequency (RF) coil development for magnetic resonance imaging (MRI) to improve both image quality and patient comfort. Notable to these improvements is the trend towards lightweight and flexible coils allowing for the conformation around a variety of anatomies and body sizes. This allows for a more comfortable patient experience and enhanced signal reception. Despite these improvements, flexible supine coils for dedicated breast imaging, or larger stretchable coil arrays for closer proximity of placement and imaging at degrees of flexion, are not available. Conventional breast coils are rigid and typically require prone positioning which creates uncomfortable pressure points along the sternum. Also, these coils do not encompass the axilla or areas in the upper chest wall. Additionally, surgical planning is performed in the supine position, making it challenging to localize lesions from prone MRI scans. To address these issues, two novel RF coil technologies are presented. Firstly, a flexible, lightweight, 60-channel supine breast coil has been constructed. This coil provides shorter scan times, greater coverage of the breasts, axilla, upper chest wall, and torso while also providing enhanced patient comfort over conventional breast coils. The second RF coil technology is a 20-channel stretchable, multipurpose coil. This coil addresses limitations of conformability around curved surfaces while allowing for the imaging of joints at a bend. Due to the stretchability, this coil exhibited enhanced signal and image quality for a variety of body sizes and anatomies, such as ankles and wrists, when compared to a flexible commercial coil.</p>

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