Journal of magnetic resonance imaging : JMRI
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J Magn Reson Imaging · May 2009
Fast dixon-based multisequence and multiplanar MRI for whole-body detection of cancer metastases.
To develop and demonstrate the feasibility of multisequence and multiplanar MRI for whole-body cancer detection. ⋯ Whole-body MRI offering essentially all the most optimal tumor-imaging sequences in a typical 1-hour time slot can potentially become an appealing "one-stop-shop" for whole-body cancer imaging.
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J Magn Reson Imaging · May 2009
3D diffusion tensor MRI with isotropic resolution using a steady-state radial acquisition.
To obtain diffusion tensor images (DTI) over a large image volume rapidly with 3D isotropic spatial resolution, minimal spatial distortions, and reduced motion artifacts, a diffusion-weighted steady-state 3D projection (SS 3DPR) pulse sequence was developed. ⋯ A true 3D DTI pulse sequence with high isotropic spatial resolution was developed for whole brain imaging in under 20 minutes. To minimize the effects of brain motion, a cardiac synchronized, multiecho, DW-SSFP pulse sequence was implemented. Motion artifacts were further reduced by a combination of linear phase correction, corrupt projection detection and rejection, sampling density reweighting, and parallel imaging reconstruction. The combination of these methods greatly improved the quality of 3D DTI in the brain.
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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
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
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.