Kiriki Masato, Jomoto Wataru, Ikeda Takashi, Kotoura Noriko
Department of Radiological Technology, Hyogo College of Medicine College Hospital.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2018;74(11):1293-1301. doi: 10.6009/jjrt.2018_JSRT_74.11.1293.
The purpose of this study was to evaluate the degree of signal attenuation generated around the stent by the susceptibility artifacts and radiofrequency (RF) shielding in phase contrast-magnetic resonance angiography (PCA) images and construct optimal PCA imaging parameters for intracranial stent lumen images. The two types of PCA images of stents (Neuroform, Enterpraise II) placed in the vascular flow phantom were imaged with different the flip angle (FA) and echo time (TE). Each original image of the vascular flow phantom was reconstructed into a coronal multiplanar reconstruction (MPR) image and a profile curve along the long axis of the stent was calculated. The reduction of in-stent signal was assessed by relative in-stent signal (RIS) calculated by comparing intra-stent signal intensity to the reference tube in the original images. When the TE was 2.3 ms, the profile curve was the highest signal intensity. However, RIS had not changed by the extension of TE. When the FA was high, the RIS showed a high value, but when it exceeded 25 degrees, the signal attenuated in the distal part of the slab.The susceptibility artifacts and RF shielding generated around the stent can be reduced by the shortest TbE (2.3 ms) and 20 degrees of FA in the PCA imaging.
本研究的目的是评估在相位对比磁共振血管造影（PCA）图像中，支架周围由磁化率伪影和射频（RF）屏蔽产生的信号衰减程度，并构建用于颅内支架管腔图像的最佳PCA成像参数。将放置在血管流动模型中的两种类型的支架（Neuroform、Enterpraise II）的PCA图像，以不同的翻转角（FA）和回波时间（TE）进行成像。将血管流动模型的每个原始图像重建为冠状面多平面重建（MPR）图像，并计算沿支架长轴的轮廓曲线。通过比较原始图像中支架内信号强度与参考管，计算相对支架内信号（RIS）来评估支架内信号的降低情况。当TE为2.3 ms时，轮廓曲线的信号强度最高。然而，随着TE的延长，RIS并未改变。当FA较高时，RIS显示出较高的值，但当超过25度时，层面远端的信号会衰减。在PCA成像中，通过最短的TbE（2.3 ms）和20度的FA，可以减少支架周围产生的磁化率伪影和RF屏蔽。
