Yamashita Y, Namimoto T, Abe Y, Takahashi M, Iwamasa J, Miyazaki K, Okamura H
Department of Radiology, Kumamoto University School of Medicine, Japan.
AJR Am J Roentgenol. 1997 Feb;168(2):513-9. doi: 10.2214/ajr.168.2.9016238.
The value of a half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence, in which high-resolution heavily T2-weighted images can be obtained within 2 sec, was evaluated in the imaging of the fetus during the second or third trimester.
Eighteen women with complicated pregnancies as revealed on a sonogram during the second and third trimesters (16-36 weeks' gestation) were studied with a 1.5-T superconductive MR imaging unit that used a body phased-array coil. After informed consent, T1-weighted fast low-angle shot images, T2-weighted turbo spin-echo images, and HASTE images were obtained without any premedication. Images were analyzed with regard to image quality, degree of blurring, visualization of the normal fetal organs, and visualization of fetal and maternal abnormalities.
On HASTE sequences, visualization of the fetal brain, visceral organs (lung, heart, liver, kidney, and bladder), extremities, and umbilical cord were significantly better than on fast low-angle shot or turbo spin-echo sequences (p < .01). In the brain, the white matter-gray matter distinction, gyrus formation, and myelination of the brain were clearly revealed by the HASTE sequence. Pathologic processes including fetal abnormalities (anomalies of the central nervous systems [n = 5], placenta previa [n = 1], and transverse lie in the third trimester [n = 1]) and maternal abnormalities (leiomyoma [n = 5], ovarian tumors [n = 3], and hydronephrosis [n = 1]) were clearly seen on HASTE imaging. The peak specific absorption rate for RF exposure in these studies was less than 1.5 W/kg.
In situations when sonography is suggestive but not definitive, MR imaging with a HASTE sequence allows clear fetal imaging with high T2-weighted contrast.
评估半傅里叶采集单次激发快速自旋回波（HASTE）序列的价值，该序列能够在2秒内获得高分辨率的重T2加权图像，用于孕中期或孕晚期胎儿成像。
对18名在孕中期和孕晚期（妊娠16 - 36周）超声检查显示有复杂妊娠情况的女性，使用配备体部相控阵线圈的1.5T超导磁共振成像设备进行研究。在获得知情同意后，未进行任何预处理即获取T1加权快速低角度激发图像、T2加权快速自旋回波图像和HASTE图像。对图像的质量、模糊程度、正常胎儿器官的可视化以及胎儿和母体异常的可视化进行分析。
在HASTE序列上，胎儿脑、内脏器官（肺、心脏、肝脏、肾脏和膀胱）、四肢及脐带的可视化明显优于快速低角度激发或快速自旋回波序列（p < 0.01）。在脑部，HASTE序列能清晰显示白质与灰质的区分、脑回形成及脑髓鞘化。包括胎儿异常（中枢神经系统异常[n = 5]、前置胎盘[n = 1]、孕晚期横位[n = 1]）和母体异常（平滑肌瘤[n = 5]、卵巢肿瘤[n = 3]、肾积水[n = 1]）在内的病理过程在HASTE成像上清晰可见。这些研究中射频暴露的峰值比吸收率小于1.5W/kg。
在超声检查提示但不明确的情况下，采用HASTE序列的磁共振成像可实现具有高T2加权对比度的清晰胎儿成像。
