Journal of magnetic resonance imaging : JMRI
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J Magn Reson Imaging · Jun 2007
High-speed 3T MR spectroscopic imaging of prostate with flyback echo-planar encoding.
Prostate MR spectroscopic imaging (MRSI) at 3T may provide two-fold higher spatial resolution over 1.5T, but this can result in longer acquisition times to cover the entire gland using conventional phase-encoding. In this study, flyback echo-planar readout trajectories were incorporated into a Malcolm Levitt's composite-pulse decoupling sequence (MLEV)-point-resolved spectroscopy sequence (PRESS) to accelerate the acquisition of large array (16 x 16 x 8), high spatial (0.154 cm(3)) resolution MRSI data by eight-fold to just 8.5 minutes. ⋯ Easy data reconstruction and the robustness of the flyback echo-planar encoding make this technique particularly suitable for the clinical setting. The short acquisition time provided by this method reduces the 3T prostate MRI/MRSI exam time, allows longer repetition times, and/or allows the acquisition of additional MR acquisitions within the same exam.
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J Magn Reson Imaging · Jun 2007
TSE with average-specific phase encoding ordering for motion detection and artifact suppression.
To detect motion-corrupted measurements in multi-average turbo-spin-echo (TSE) acquisitions and reduce motion artifacts in reconstructed images. ⋯ The proposed method combines a novel data acquisition scheme, a robust motion detection algorithm, and a simple motion correction algorithm. It is effective in reducing motion artifacts for images corrupted by either bulk motion or local motion that occasionally happens during data acquisition.
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J Magn Reson Imaging · Jun 2007
Black-blood T2* technique for myocardial iron measurement in thalassemia.
To compare the effectiveness and reproducibility of a new black-blood sequence vs. a conventional bright-blood gradient-echo T2* sequence for myocardial iron overload measurement in thalassemia. ⋯ The black-blood T2* technique yields high-contrast myocardial images, provides clearly depicted myocardial borders, and avoids blood signal contamination of the myocardium while yielding improvements in interobserver variability.
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To evaluate the impact of data quality on the localization of brain activation in functional magnetic resonance imaging (fMRI) and to explore whether the temporal contrast-to-noise-ratio (CNR) provides a quantitative parameter to estimate fMRI quality. ⋯ Calculating the CNR using an adaptive low-pass filter gives similar results to a GLM-based approach and could be advantageous for cases in which the hemodynamic response function (HRF) differs significantly from common assumptions. The CNR can be used to identify and exclude runs with suboptimal CNR, and to identify sessions with insufficient data quality. The CNR may serve as a quantitative and intuitive parameter to assess the performance and quality of clinical fMRI investigations, including information on both functional performance (contrast) and data quality (noise caused by the system and physiology).
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J Magn Reson Imaging · Jun 2007
High temporal resolution breathheld 3D FIESTA CINE imaging: validation of ventricular function in patients with chronic myocardial infarction.
To develop a gated single-breathhold, high temporal resolution three-dimensional (3D) CINE imaging technique and to evaluate its accuracy in volumetric and functional quantification in patients with chronic myocardial infarction. ⋯ High temporal resolution 3D CINE SSFP imaging of the whole heart can be obtained in a single breathhold and yield ventricular function measurements similar to 2D CINE methods.