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Browsing by Author "Dale, Brian M."
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Item In vivo sodium MR imaging of the abdomen at 3T(Springer Nature, 2015-10) James, Judy R.; Panda, Anshuman; Lin, Chen; Dydak, Ulrike; Dale, Brian M.; Bansal, Navin; Radiology and Imaging Sciences, School of MedicineURPOSE: Transmembrane sodium ((23)Na) gradient is critical for cell survival and viability and a target for the development of anti-cancer drugs and treatment as it serves as a signal transducer. The ability to integrate abdominal (23)Na MRI in clinical settings would be useful to non-invasively detect and diagnose a number of diseases in various organ systems. Our goal in this work was to enhance the quality of (23)Na MRI of the abdomen using a 3-Tesla MR scanner and a novel 8-channel phased-array dual-tuned (23)Na and (1)H transmit (Tx)/receive (Rx) coil specially designed to image a large abdomen region with relatively high SNR. METHODS: A modified GRE imaging sequence was optimized for (23)Na MRI to obtain the best possible combination of SNR, spatial resolution, and scan time in phantoms as well as volunteers. Tissue sodium concentration (TSC) of the whole abdomen was calculated from the inhomogeneity-corrected (23)Na MRI for absolute quantification. In addition, in vivo reproducibility and reliability of TSC measurements from (23)Na MRI was evaluated in normal volunteers. RESULTS: (23)Na axial images of the entire abdomen with a high spatial resolution (0.3 cm) and SNR (~20) in 15 min using the novel 8-channel dual-tuned (23)Na and (1)H transmit/receive coil were obtained. Quantitative analysis of the sodium images estimated a mean TSC of the liver to be 20.13 mM in healthy volunteers. CONCLUSION: Our results have shown that it is feasible to obtain high-resolution (23)Na images using a multi-channel surface coil with good SNR in clinically acceptable scan times in clinical practice for various body applications.Item Rotating single-shot acquisition (RoSA) with composite reconstruction for fast high-resolution diffusion imaging(Wiley, 2018-01) Wen, Qiuting; Kodiweera, Chandana; Dale, Brian M.; Shivraman, Giri; Wu, Yu-Chien; Radiology and Imaging Sciences, School of MedicinePURPOSE: To accelerate high-resolution diffusion imaging, rotating single-shot acquisition (RoSA) with composite reconstruction is proposed. Acceleration was achieved by acquiring only one rotating single-shot blade per diffusion direction, and high-resolution diffusion-weighted (DW) images were reconstructed by using similarities of neighboring DW images. A parallel imaging technique was implemented in RoSA to further improve the image quality and acquisition speed. RoSA performance was evaluated by simulation and human experiments. METHODS: A brain tensor phantom was developed to determine an optimal blade size and rotation angle by considering similarity in DW images, off-resonance effects, and k-space coverage. With the optimal parameters, RoSA MR pulse sequence and reconstruction algorithm were developed to acquire human brain data. For comparison, multishot echo planar imaging (EPI) and conventional single-shot EPI sequences were performed with matched scan time, resolution, field of view, and diffusion directions. RESULTS: The simulation indicated an optimal blade size of 48 × 256 and a 30 ° rotation angle. For 1 × 1 mm2 in-plane resolution, RoSA was 12 times faster than the multishot acquisition with comparable image quality. With the same acquisition time as SS-EPI, RoSA provided superior image quality and minimum geometric distortion. CONCLUSION: RoSA offers fast, high-quality, high-resolution diffusion images. The composite image reconstruction is model-free and compatible with various diffusion computation approaches including parametric and nonparametric analyses. Magn Reson Med 79:264-275, 2018. © 2017 International Society for Magnetic Resonance in Medicine.