Nazir Aalia, Afzal Muhammad, Buzdar Saeed Ahmad
Department of Physics, The Islamia University of Bahawalpur, Pakistan.
J Pak Med Assoc. 2010 Jun;60(6):470-3.
This study focuses on the diverse effects of MRI parameters on image quality using widely available imaging pulse sequences.
A tissue equivalent gel system has been used for Magnetic Resonance Imaging by using Xylenol orange dye with Fricke-Benzoic solution which was formulated by Kelly R.G (1998). The gel system was radiated while using 6MV photons from Varian Clinic Linear Accelerator.
The qualitative analysis include the effect of TR and TE on signal nonuniformity according to which the escalating repetition time gives a uniform signal having the average values calculated are 0.76%, 0.83%, 1.43% and 1.89% for the conventional spin echo (CSE), fast spin echo (FSE), gradient recalled echo (GRE) and fluid attenuated inversion recovery (FLAIR) respectively. FLAIR showed contradictory results due to longitudinal relaxation of the signal. This is because, at the longer value of inversion time (TI), the signal from simple fluids is nulled, thus reducing signal intensity.
The evaluation of signal uniformity for different pulse sequences demonstrates that the repetition time (TR) affects the signal homogeneity as it maintains image quality for CSE and FSE. However, a careful selection is required for FLAIR due to its sensitive behaviour for image uniformity.
本研究利用广泛可用的成像脉冲序列，聚焦于磁共振成像（MRI）参数对图像质量的多种影响。
一种组织等效凝胶系统已被用于磁共振成像，该系统使用了由凯利·R·G（1998年）配制的含有二甲酚橙染料和弗里克 - 苯甲酸溶液。在使用瓦里安临床直线加速器产生的6兆伏光子时，对该凝胶系统进行了辐射。
定性分析包括TR和TE对信号不均匀性的影响，据此，不断增加的重复时间会产生均匀信号，对于传统自旋回波（CSE）、快速自旋回波（FSE）、梯度回波（GRE）和液体衰减反转恢复（FLAIR）序列，计算得到的平均值分别为0.76%、0.83%、1.43%和1.89%。由于信号的纵向弛豫，FLAIR显示出矛盾的结果。这是因为，在较长的反转时间（TI）值时，来自单纯液体的信号被消除，从而降低了信号强度。
对不同脉冲序列信号均匀性的评估表明，重复时间（TR）会影响信号均匀性，因为它能维持CSE和FSE的图像质量。然而，由于FLAIR对图像均匀性的敏感特性，需要谨慎选择。
