Browsing by Subject "Endorectal coil"
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Item Open Access Design and implementation of internal MRI coils using ultimate intrinsic(2006) Eryaman, YiğitcanIn this thesis, methods for optimization of internal magnetic resonance imaging coils have been developed. As a sample optimization endorectal coils were optimized. As the first step ultimate intrinsic signal-to-noise ratio for internal coils was formulated. This value was used as a measure of performance of the internal MRI coils. The related optimization problem was divided into two sub problems: length optimization and cross-sectional optimization. For the length optimization length of a single loop rectangular coil was optimized in order to obtain maximum intrinsic signal to noise ratio at the prostate region. For the cross-sectional optimization designs with different cross-sectional geometries were implemented and tested in saline solution phantom. The designs that gave a significant improvement over the conventional loop coil were favored and the related design ideas were used for the design of an optimized coil. Finally optimized coil was tested in a saline solution phantom model and its performance was calculated.Item Open Access Phased-array MRI of canine prostate using endorectal and endourethral coils(John Wiley & Sons, Inc., 2003) Yung, A. C.; Oner, A. Y.; Serfaty, J-M.; Feneley, M.; Yang, X.; Atalar, ErginA four-channel phased array consisting of one surface coil, two endorectal coils, and one flexible endourethral loop coil was designed for MRI of the canine prostate. The endorectal coils provide high signal in the posterior region of the prostate, while the endourethral and surface coils are sensitive to the central and anterior regions of the prostate. Gel phantom experiments indicate that the proposed phased-array configuration generates 15 times more signal-to-noise ratio (SNR) than a combination of two surface coils and one endorectal coil within the posterior region of the prostate; the performance of the two configurations is comparable near the anterior prostate surface. Ultimate intrinsic SNR (UISNR) analysis was used to compare the proposed phased array's performance to the best possible SNR for external coils. This analysis showed that the proposed phased array outperforms the best-case external coil within the posterior and central regions of the prostate by up to 20 times. In canine experiments in vivo, high-resolution fast spin-echo (FSE) images of the prostate were obtained with a pixel size of 230 μm obtained in 3 min 12 s. The proposed phased-array design potentially can be used to increase the accuracy of prostate cancer staging and the feasibility of MR-guided prostate interventions. © 2003 Wiley-Liss, Inc.