Journal of magnetic resonance imaging : JMRI
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J Magn Reson Imaging · May 2009
Microperfusion-induced elevation of ADC is suppressed after contrast in breast carcinoma.
To investigate the effect of gadolinium (Gd)-DTPA on the apparent diffusion coefficient (ADC) of breast carcinoma and to analyze the relationship between pre/postcontrast ADC and the degree of contrast enhancement. ⋯ Postcontrast ADC exhibited lower values than precontrast ADC, which is thought to reflect suppression of the microperfusion-induced effect on diffusion-weighted imaging. Postcontrast ADC may be a better indicator than precontrast ADC to reflect malignant potential of tumors.
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J Magn Reson Imaging · May 2009
Comparative StudyComparison of spiral imaging and SENSE-EPI at 1.5 and 3.0 T using a controlled cerebrovascular challenge.
To quantitatively compare spiral imaging and sensitivity-encoded-echo-planar-imaging (SENSE-EPI) methods for blood oxygen level-dependent (BOLD) imaging using controlled changes in the end-tidal partial pressure of CO(2) (PetCO(2)) to provide a global BOLD response. Specifically, we examined susceptibility-field-gradient effects on the BOLD sensitivity throughout the brain. ⋯ The results at 3.0 T suggest that, compared with spiral imaging, SENSE-EPI reduces signal loss associated with susceptibility field gradients in affected regions without affecting BOLD sensitivity. This study also demonstrates a unique application of controlled PetCO(2) changes to quantitatively compare BOLD techniques, which may be useful for the design of future fMRI studies.
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J Magn Reson Imaging · May 2009
Slice offset frequency and shim adjustment for interactive steady-state free-precession (SSFP) imaging.
To devise a method allowing real-time optimization of center frequency (CF) and shim for an interactive steady-state free-precession (SSFP) sequence by reformatting a previously acquired field map in the same orientation as the interactive acquisition. ⋯ The proposed method demonstrates how CF and shim can be optimized for any interactively positioned slice, resulting in reduced off-resonance artifacts.
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J Magn Reson Imaging · May 2009
Non-contrast-enhanced MR portography with time-spatial labeling inversion pulses: comparison of imaging with three-dimensional half-fourier fast spin-echo and true steady-state free-precession sequences.
To compare and evaluate images acquired with two different MR angiography (MRA) sequences, three-dimensional (3D) half-Fourier fast spin-echo (FSE) and 3D true steady-state free-precession (SSFP) combined with two time-spatial labeling inversion pulses (T-SLIPs), for selective and non-contrast-enhanced (non-CE) visualization of the portal vein. ⋯ Both 3D half-Fourier FSE and true SSFP scans with T-SLIPs enabled selective non-CE visualization of the portal vein. Half-Fourier FSE was considered appropriate for intrahepatic portal vein visualization, and true SSFP may be preferable when visualization of the MPV is required.