Buecker A, Adam G, Neuerburg J M, Glowinski A, van Vaals J J, Guenther R W
Clinic for Diagnostic Radiology, University of Technology Aachen, Germany.
J Magn Reson Imaging. 1998 Jul-Aug;8(4):955-9. doi: 10.1002/jmri.1880080426.
The purpose of this study was to demonstrate the utility of a T2-weighted single shot turbo spin-echo technique--the so-called "Local Look" (LoLo) and more recently renamed "Zoom Imaging" technique--for MR-guided percutaneous interventions. We performed 28 procedures on 22 patients using a 1.5-T system for MR guidance. All procedures were controlled with the LoLo technique, which acquires T2-weighted images in 600 msec. This is achieved by using a small field of view (250 x 125 mm) along with a maximum echo train length, the so-called "single shot method." To prevent backfolding artifacts, the 90 degrees and 180 degrees pulses were oriented orthogonally to each other. Because signal is created only in the region in which the pulses overlap, no backfolding can occur from outside this area. Half of the biopsies were additionally monitored using a fast gradient-echo sequence, which was compared with the LoLo technique. All of the procedures were technically successful, and there were no procedural complications. The LoLo technique produced images that had good contrast between the lesion and the needle artifact, and the artifact size was smaller than that produced by the gradient-echo technique. Subjective judgment of the ability to accurately delineate the needle tip indicated that the LoLo technique was either superior to (73%) or equal to (27%) the gradient-echo sequence in all cases. The LoLo technique is an accurate and effective method for MR guidance of percutaneous procedures, because it shows good lesion contrast and small needle artifacts. The additional use of a gradient-echo sequence during the procedure planning stage is advisable in more difficult cases, particularly when adjacent blood vessels are a concern. Monitoring of the needle tip is best performed with the LoLo technique.
本研究的目的是证明一种T2加权单次激发快速自旋回波技术——即所谓的“局部观察”（LoLo）技术，最近更名为“缩放成像”技术——在磁共振引导下经皮介入操作中的实用性。我们使用1.5-T系统对22例患者进行了28次操作以进行磁共振引导。所有操作均采用LoLo技术进行控制，该技术可在600毫秒内获取T2加权图像。这是通过使用小视野（250×125毫米）以及最大回波链长度，即所谓的“单次激发方法”来实现的。为防止折叠伪影，90°和180°脉冲相互正交。由于信号仅在脉冲重叠的区域产生，因此该区域外不会发生折叠。一半的活检操作还使用快速梯度回波序列进行监测，并与LoLo技术进行比较。所有操作在技术上均获成功，且无操作相关并发症。LoLo技术所产生的图像在病变与针伪影之间具有良好的对比度，且伪影尺寸小于梯度回波技术所产生的伪影。对准确描绘针尖能力的主观判断表明，在所有病例中，LoLo技术要么优于（73%）要么等同于（27%）梯度回波序列。LoLo技术是磁共振引导经皮操作的一种准确有效的方法，因为它显示出良好的病变对比度和较小的针伪影。在更困难的病例中，尤其是当需要关注相邻血管时，建议在操作规划阶段额外使用梯度回波序列。对针尖的监测最好采用LoLo技术。
