Assessment the Optimal Effect of Time of Repetition: Extrinsic Pulse Parameter on Gd-DTPA Enhanced, Spin-Echo T1-Weighted MR Images under Low Magnetic Field Strength

The contrast agent concentration, the time of repetition (TR) and magnetic field strength are significant parameters that influence for the accurate signal intensity (SI) in quantitative Magnetic Resonance Imaging (MRI). Therefore, this study was conducted to investigate and refine the dependence and the optimal effect of Time of Repetition (TR) on the relationship between signal intensity and Gd-DTPA (Gadolinium-diethylene-triaminepenta-acetic acid) concentration, after applying two-dimensional (2D) Spin Echo (SE) pulse sequence under low-field MRI. In addition to that, the optimal concentration of Gd-DTPA at given sequence parameters at low-field MRI was also evaluated. A water-filled phantom was constructed for a range of Gd-DTPA concentrations (0 - 6 mmol/L) and the mean signal intensities (SIs) were assessed in the defined region of interest on T1-weighted images with different TR values (40 - 2000 ms). The generated signal-concentration curves for Gd-DTPA revealed that increasing TR was associated with the increase of the overall SIs and the maximum relationship between SI to concentration. Moreover, the required Gd-DTPA concentration to produce the maximum SI was associated to decrease with the increase of TR. In addition to this, the application of beyond 100 ms TR values in this study with relatively higher concentrations (beyond 1 - 2 mmol/L) has resulted predominantly non-linear patterns in the signal-concentration curves and it appears the saturation or decay of the SIs due to T2 effect. From these results, it can be suggested that the selection of relatively lower Gd-DTPA concentration ( mmol/L) with less than 800 ms (<800 ms) TR values can produce a better linear relationship between the concertation and SIs in T1-weighted SE low field contrast-enhanced MRI. Furthermore, this study also outlined the significance and necessity of the optimization of TR in SE sequence in low field MRI prior to a particular examination.

低场强MRI T2^＊ WI FFE序列在颅脑血管性及出血性疾病中的应用研究

目的：探讨低场强MRI T2＊WI FFE序列成像在颅脑血管性及出血性病变检查中的敏感性。方法：分析110例临床可疑颅脑出血患者的常规MRI序列,包括自旋回波（SE）T1WI、快速自旋回波（TSE）T2WI、液体衰减反转恢复序列（T2-FLAIR）,以及T2＊快速场回波序列（T2＊WI FFE）资料,比较常规序列、T2＊WI FFE序列对颅脑出血病灶的显示率,分析其信号特征,并探讨T2＊WIFFE序列的可行性。结果：T2＊WI FFE序列为显示颅脑出血灶最敏感的序列,能显示常规序列所不能显示的脑微出血。无论在检出脑出血灶,还是图像信噪比,T2＊WI FFE均能满足临床需求。结论：低场强MRI T2＊WI FFE序列能明显提高颅脑出血灶的检出率,进而提高颅脑血管性及出血性疾病的早期诊断率。其在临床颅脑出血筛选方面具有常规MRI序列无法替代的作用。

膝关节外伤在磁共振和64排螺旋CT的诊断对比

目的探讨膝关节外伤在磁共振和64排螺旋CT的诊断对比情况。方法分析2012年1—12月该院膝关节外伤患者120例临床资料,观察膝关节外伤在64排螺旋CT、磁共振和手术证实的诊断结果。结果 64排螺旋CT诊断结果骨质损伤、韧带损伤、半月板损伤、关节积液诊断准确率明显低于磁共振的诊断结果,差异无统计学意义(χ2=0.351、0.372、0.306、0.315,P>0.05)。结论多排螺旋CT和MRI的合理检查可以让骨科医生对膝关节损伤情况提前做出全面而细致的了解,提早做出手术预案。

国产低场0.4T磁共振成像在诊断膝关节损伤中的临床应用价值

目的探讨膝关节损伤在国产低场0.4T磁共振成像(MRI)中的影像学表现、病理基础及其临床意义。方法回顾性分析X线检查阴性、经手术或关节镜治疗膝关节损伤60例的MRI表现。结果膝关节损伤60例中隐性骨折4例,MRI表现为T1、T2序列可见斜形、不规则形低信号影;关节韧带损伤40例,MRI表现为低信号条索状韧带影扭曲位置失常或局灶性、弥漫性信号增粗、不连续、消失或出现不规则异常信号影;半月板损伤30例,MRI表现为脂肪抑制(STIR)序列低信号,半月板影出现点状、条状或片状高信号影。本组中骨挫伤36例,关节积液58例,关节鼠1例,关节周软组织肿胀59例。结论国产低场0.4TMRI可以清晰显示膝关节隐性骨折、韧带、半月板、关节腔、滑膜及肌腱等形态、位置及信号的变化,在膝关节损伤的诊断及临床应用上具有很高价值,是膝关节损伤的理想诊断方法。