Journal of magnetic resonance imaging : JMRI
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J Magn Reson Imaging · Nov 1998
Comparative StudyT2-weighted breath-hold MRI of the liver at 1.0 T: comparison of turbo spin-echo and HASTE sequences with and without fat suppression.
To compare the clinical usefulness of T2-weighted breath-hold sequences for imaging the liver, 33 patients with 97 focal hepatic lesions were studied with a 1.0-T scanner by using T2-weighted breath-hold turbo spin-echo (SE) sequences and T2-weighted breath-hold half-Fourier single-shot turbo SE (HASTE) sequences with and without fat suppression. Images were quantitatively analyzed for liver signal-to-noise ratio (SNR) and lesion-to-liver contrast-to-noise ratios (CNR). Qualitative analysis was performed for lesion conspicuity, motion artifacts, and anatomic sharpness of extrahepatic structures. ⋯ This study suggests that turbo SE sequence with fat suppression is most useful for breath-hold T2-weighted liver imaging at 1.0 T. Addition of imaging without fat suppression can be considered for evaluating extrahepatic structures. HASTE sequence may have a role for imaging uncooperative patients due to absence of motion artifacts.
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J Magn Reson Imaging · Nov 1998
Comparative StudyComparison of ultrafast half-Fourier single-shot turbo spin-echo sequence with turbo spin-echo sequences for T2-weighted imaging of the female pelvis.
So that we might evaluate the ultrafast half-Fourier single-shot turbo spin-echo (HASTE) sequence in T2-weighted MRI of the female pelvis and compare it with the turbo spin-echo (TSE) sequence, we prospectively studied 60 consecutive females with suspected abnormalities of the pelvis. For all MR examinations, we used a 1.5-T superconductive magnet with a phased array coil. The HASTE sequence was applied with TR/effective TE/echo train = infinity/90/64 and a 128 x 256 matrix (acquisition time: .3 sec/slice), conventional TSE imaging with 3,400 to 5,000/132/15 and a 128 x 256 matrix (mean acquisition time: 2 min 4 sec), and high-resolution TSE imaging with 3,400 to 5,000/132/15 and a 300 x 512 matrix (6 min 4 sec). ⋯ Compared with high-resolution TSE, HASTE provided clearer visualization of large leiomyomas and ovarian tumors but slightly poorer visualization of uterine cancer. In occlusion, HASTE sequence generates higher contrast and is free from motion and chemical shift artifact with much higher time efficacy. Because of limited image resolution, the HASTE sequence should be used when the high-resolution TSE imaging is suboptimal.
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J Magn Reson Imaging · Nov 1998
Comparative StudyFat suppressed MRI of articular cartilage with a spatial-spectral excitation pulse.
We developed a three-dimensional, gradient-recalled-echo imaging technique that incorporates a short-duration spatial-spectral excitation pulse from the family of binomial pulses. Binomial pulses of different orders were tested on phantoms and on normal volunteers to find the composite pulse that produced in the shortest duration the most reliable fat suppression. ⋯ Images of the knees of volunteers produced with the composite RF pulse have contrast between fat and articular cartilage equivalent to that on images created by the gradient-recalled-echo imaging technique employing a conventional chemsat pulse. The optimum RF pulse consisted of three amplitude- and phase-modulated pulses combined with unipolar slice-select gradients.