Comparison of ultrafast half‐Fourier single‐shot turbo spin‐echo sequence with turbo spin‐echo sequences for T2‐weighted imaging of the female pelvis

Abstract

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). Although the lesion conspicuity for the HASTE sequence was less than that for the high-resolution TSE sequences, artifacts (including ghosting, bowel motion, susceptibility difference, and chemical shift) were negligible on HASTE images of all patients. The lesion conspicuity for the HASTE sequence was significantly better than for the conventional TSE sequence. In spite of the very short acquisition time, the subjective scoring of the overall image quality for the HASTE sequence was significantly higher than for the conventional TSE sequence (P < .01) and were slightly lower than for the high-resolution TSE sequence. 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.

Comparison of True FISP with Turbo SE in Ovarian Imaging

“…However, these sequences-such as single-shot FSE with half-Fourier acquisition and multi-shot echoplanar imaging-could not replace TSE sequencing because of their limited spatial resolution and low tissue contrast. [8][9][10] True FISP provides a higher signal-to-noise (S W N) ratio for the assessment of uterine anatomy deˆnition, as reported previously. 7 Therefore, it is natural that True FISP can be expected to function as an innovative and faster T2-weighted imaging method for evaluating ovarian pathology.…”

MRI of the Pelvis in Women: 3D Versus 2D T2-Weighted Technique

“…Studies have been conducted to compare 2D and 3D half-Fourier TSE sequences with standard 2D T2-weighted TSE sequences in MRI of the female pelvis. These studies [7][8][9] showed good image quality and improved time efficiency with the 2D half-Fourier TSE sequence and higher contrast, improved time efficiency, and superior through-plane resolution (2-3 mm) with the 3D half-Fourier TSE sequence. However, no attempt was made in those studies to generate multiplanar reconstructions of the 3D source data sets because the slice thickness of 2-3 mm seemed insufficient for acquisition of reformations of high quality.…”

T2‐weighted MRI of the female pelvis: Comparison of breath‐hold fast‐recovery fast spin‐echo and nonbreath‐hold fast spin‐echo sequences

“…The other method to speed T2‐weighted FSE imaging is to use a longer echo train length (5, 8). Single‐shot FSE with half‐Fourier acquisition, such as HASTE, has been introduced for the complement sequence in the evaluation of the female pelvis (19, 20).…”

“…Single‐shot FSE with half‐Fourier acquisition, such as HASTE, has been introduced for the complement sequence in the evaluation of the female pelvis (19, 20). This sequence is fast enough to freeze the peristalsis of the intestine and respiratory motion of the abdominal wall; thus, imaging free of motion‐artifacts can be obtained (8). However, in comparison to high‐resolution T2‐weighted FSE or turbo spin‐echo imaging, less spatial resolution and less lesion conspicuity are problems because the use of very long echo train length may cause blurring effects in single‐shot imaging, and may induce magnetization transfer effects that could reduce T2 contrast (3, 8, 21).…”

“…Another way to facilitate a short imaging time with an FSE sequence is the use of a relatively short repetition time (TR) of around 2000 msec. T2‐weighted FSE imaging is usually utilized with imaging parameters such as a TR of about 4000–5000 msec and echo train length of about 8–16 to image the whole pelvis (4, 5, 8). FSE with a shorter TR (around 2000 msec) might suffer from less signal intensities due to saturation of the protons.…”