Journal of magnetic resonance imaging : JMRI
-
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.
-
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.
-
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.
-
J Magn Reson Imaging · Sep 1998
Comparative StudyMR versus fluoroscopic guidance of a catheter/guidewire system: in vitro comparison of steerability.
Our purpose in this study was to evaluate the steerability of a combined catheter guidewire system with MR tracking in an open-configuration .5T MR system and compare it with fluoroscopic guidance. Experiments were performed with an aorta-shaped glass phantom with different-size branches connected to a roller flow pump to simulate pulsatile flow. A .035" guidewire was used in conjunction with a 5F Cobra 2-shaped catheter. ⋯ However, cannulation under fluoroscopic guidance with standard angiography devices required significantly less time (P < .05). Selective catheterization of small branch vessels is possible with active MR tracking of a combined catheter/guidewire system. Limitations of MR tracking device material and design result in a considerable lengthening of the cannulation procedures.
-
J Magn Reson Imaging · Sep 1998
Comparative StudyComparison of multishot turbo spin echo and HASTE sequences for T2-weighted MRI of liver lesions.
The purpose of this study was to compare the relative usefulness of multishot turbo spin echo (TSE) and half-Fourier single-shot turbo spin echo (HASTE) for determination of optimal breath-hold fast T2-weighted technique in terms of lesion detection, lesion-to-liver contrast-to-noise ratio (CNR), and image quality. The images of TSE with and without fat suppression (FS) and of HASTE with and without FS were retrospectively reviewed for 49 patients with 128 lesions. Without FS, TSE and HASTE images allowed depiction of focal hepatic masses (112 of 128, sensitivity = 87.5%) at the same rate. ⋯ The CNR of hemangioma was distinct from that of solid tumors and cystic lesions in all sequences, and the range of CNR in each group of pathologies overlapped less and were well separated in the HASTE sequences. HASTE sequences produced better image quality with fewer artifacts (P < .0001). The results of this study suggest that HASTE sequences allow differentiation between solid tumors, hemangiomas, and cystic lesions in terms of CNR, producing fewer image artifacts, with acceptable sensitivity in lesion detection.