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 (MR...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.展开更多
目的:回顾性分析21例放射性脑病患者41处病灶的低场M R I表现,探讨低场M R I对于放射性脑损伤诊断的准确性。方法:对21例病例进行M R扫描,分析其M R I表现。结果:21例经临床随访证实为放射性脑病均得以正确诊断。结论:放射性脑病的M R ...目的:回顾性分析21例放射性脑病患者41处病灶的低场M R I表现,探讨低场M R I对于放射性脑损伤诊断的准确性。方法:对21例病例进行M R扫描,分析其M R I表现。结果:21例经临床随访证实为放射性脑病均得以正确诊断。结论:放射性脑病的M R I表现具有一定特征,结合放射治疗病史及临床表现,低场M R I可以对放射性脑损伤做出正确诊断。展开更多
目的:探讨低场M R I在诊断新生儿缺血缺氧性脑病的作用及价值。方法:对20例临床诊断为缺血缺氧性脑病的新生儿行低场M R I检查,并对其低场M R I表现进行分析。结果:所有患儿均有不同程度的脑损害,其中广泛脑水肿5例,颅内出血10例,皮质...目的:探讨低场M R I在诊断新生儿缺血缺氧性脑病的作用及价值。方法:对20例临床诊断为缺血缺氧性脑病的新生儿行低场M R I检查,并对其低场M R I表现进行分析。结果:所有患儿均有不同程度的脑损害,其中广泛脑水肿5例,颅内出血10例,皮质下及脑室旁白质损害9例,丘脑、基底节区和脑干背侧异常信号7例。结论:低场M R I能准确的反映出新生儿缺血缺氧性脑病的脑损害程度。展开更多
文摘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.
文摘目的:回顾性分析21例放射性脑病患者41处病灶的低场M R I表现,探讨低场M R I对于放射性脑损伤诊断的准确性。方法:对21例病例进行M R扫描,分析其M R I表现。结果:21例经临床随访证实为放射性脑病均得以正确诊断。结论:放射性脑病的M R I表现具有一定特征,结合放射治疗病史及临床表现,低场M R I可以对放射性脑损伤做出正确诊断。
文摘目的:探讨低场M R I在诊断新生儿缺血缺氧性脑病的作用及价值。方法:对20例临床诊断为缺血缺氧性脑病的新生儿行低场M R I检查,并对其低场M R I表现进行分析。结果:所有患儿均有不同程度的脑损害,其中广泛脑水肿5例,颅内出血10例,皮质下及脑室旁白质损害9例,丘脑、基底节区和脑干背侧异常信号7例。结论:低场M R I能准确的反映出新生儿缺血缺氧性脑病的脑损害程度。
