Takeuchi Naohide, Mitsuyasu Hiromichi, Nakanishi Tomonori, Nishimura Sumako, Shimoto Takeshi, Higaki Hidehiko, Hashizume Makoto, Iwamoto Yukihide
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka.
Fukuoka Igaku Zasshi. 2011 May;102(5):185-94.
To evaluate the magnetic susceptibility artifacts associated with different frequency-encoding gradient directions for an angled cephalomedullary device of the proximal femur, and to determine the optimal extremity positioning for reducing artifacts using 0.4 T open MR imaging.
Two different angular devices made of titanium alloy and stainless steel were used. The images were obtained with the frequency-encoding gradient parallel to the rod (Group R) and parallel to the lag screw (Group L). The device positioning was altered in order to obtain images with frequency-encoding gradient parallel to the rod and parallel to the lag screw. The artifact areas associated with the whole device and the lag screw were statistically evaluated.
For both devices, the mean artifact area in Group L was significantly larger than that in Group R (p<0.05). However, the mean artifact area of the lag screw only in Group L was significantly smaller than that in Group R (p<0.05).
Susceptibility artifacts for angled cephalomedullary devices can be minimized when the frequency-encoding gradient is parallel to the long axis of the regions of interest. Open MR imaging enables us to obtain the optimal orientation for minimizing susceptibility artifacts.
评估股骨近端成角髓内装置在不同频率编码梯度方向下的磁化率伪影，并使用0.4 T开放式磁共振成像确定减少伪影的最佳肢体定位。
使用两种由钛合金和不锈钢制成的不同角度装置。图像采集时频率编码梯度分别平行于杆（R组）和平行于拉力螺钉（L组）。改变装置定位以获取频率编码梯度平行于杆和平行于拉力螺钉的图像。对与整个装置和拉力螺钉相关的伪影区域进行统计学评估。
对于两种装置，L组的平均伪影面积均显著大于R组（p<0.05）。然而，仅L组中拉力螺钉的平均伪影面积显著小于R组（p<0.05）。
当成角髓内装置的频率编码梯度平行于感兴趣区域的长轴时，磁化率伪影可降至最低。开放式磁共振成像使我们能够获得使磁化率伪影最小化的最佳方向。
