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
Objective To investigate the clinical value of different magnetic resonance (MR) pulse sequences in diagnosis of spinal metastatic tumor. Methods Fifteen patients with clinically suspected spinal metastatic tumor were...Objective To investigate the clinical value of different magnetic resonance (MR) pulse sequences in diagnosis of spinal metastatic tumor. Methods Fifteen patients with clinically suspected spinal metastatic tumor were included in this study. These patients were with documented primary tumors. Four MR pulse sequences, T1-weighted spin echo (T1WI SE), T2-weighted fast spin echo (T2WI FSE), short time inversion recovery (STIR), and gradient echo 2-D multi echo data imaging combination (GE Me-2D) were used to detect spinal metastasis. Results Fifteen vertebral bodies were entire involvement, 38 vertebral bodies were section involvement, and totally 53 vertebral bodies were involved. There were 19 focal infections in pedicle of vertebral arch, 15 metastases in spinous process and transverse process. Fifty-three vertebral bodies were abnormal in T1WI SE and GE Me-2D, 35 vertebral bodies were found abnormal in T2WI FSE, and 50 vertebral bodies were found abnormal in STIR. The verges of focal signal of involved vertebral bodies were comparatively clear in T1WI SE, comparatively clear or vague in T2WI FSE, vague in STIR, and clear in GE Me-2D.Conclusions GE Me-2D may be the most sensitive technique to detect metastases. So three sequences (T1WI SE, T2WI FSE, GE Me-2D) can demonstrate the early changes of spinal metastasis roundly.展开更多
目的探讨三维梯度自旋回波(GRASE)序列在老年患者磁共振胆胰管成像(MRCP)中的应用价值。方法纳入MRCP检查的老年患者63例。同时采集屏气2D-FSE、屏气3D-GRASE和呼吸触发3D-FSE序列。计算图像的信噪比、对比噪声比和对比度,并对图像质量...目的探讨三维梯度自旋回波(GRASE)序列在老年患者磁共振胆胰管成像(MRCP)中的应用价值。方法纳入MRCP检查的老年患者63例。同时采集屏气2D-FSE、屏气3D-GRASE和呼吸触发3D-FSE序列。计算图像的信噪比、对比噪声比和对比度,并对图像质量进行主观评价,包括伪影、背景抑制、总体图像质量和胆胰管各分支的显示情况。组间比较采用单因素ANOVA检验或非参数Kruskal-Wallis检验。结果GRASE序列的伪影评分高于2D-FSE序列,差异具有统计学意义(4.24±0.69 vs 3.76±1.03,P<0.05),但与3D-FSE序列之间差异无统计学意义(P>0.05)。GRASE序列背景抑制的评分高于2D-FSE序列(P<0.05)。在图像的总体质量评分中,GRASE序列略高于3D-FSE序列,差异无统计学意义(4.29±0.83 vs 4.16±0.79,P>0.05),两者均高于2D序列,差异均有统计学意义(P<0.05)。GRASE序列的CNR、CR与3D-FSE序列相近,差异无统计学意义(P>0.05),均高于2D-FSE序列,差异均有统计学意义(P均<0.05)。GRASE序列在胆总管、肝总管、右肝管后支、左肝管内、外支的显示的显示能力与3D-FSE序列无差别。GRASE序列在右肝管前支的显示能力不如3D-FSE序列(P<0.05)。结论GRASE获得胆胰管的图像质量与3D-FSE序列接近,高于2D-FSE序列,为老年人疾病诊断提供影像学依据。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.
文摘目的探讨基于联合压缩感知(Compressed Sensing,CS)平面回波成像(Echo Planer Imaging,EPI)的动脉自旋标记(Arterial Spin Labeling,ASL)技术,即EPICS-ASL序列在脑灌注成像中的应用价值,并与传统EPI-ASL序列进行比较。方法前瞻性收集30例志愿者行EPICS-ASL和传统EPI-ASL序列扫描。在ASL原始图上选取基底节、灰质、白质、脑干和小脑作为感兴趣区(Region of Interest,ROI),测量并计算各ROI的信噪比(Signal to Noise Ratio,SNR)和灰质/白质对比噪声比(Contrast to Noise Ratio,CNR灰质/白质);2名医师独立双盲采用4分法主观评估两组图像质量。采用配对t检验比较两组图像的SNR和CNR灰质/白质,采用秩和检验比较两组图像主观评分结果。结果客观评价,EPICS-ASL组各ROI的SNR和CNR灰质/白质均优于EPI-ASL组各ROI的SNR和CNR灰质/白质(均P<0.001);主观评价,EPICS-ASL组的图像质量评分也优于EPI-ASL组(均P<0.001)。结论EPICS-ASL序列显著优于传统EPI-ASL序列的图像SNR和CNR,图像质量更高,具有进一步临床应用的潜力。
文摘Objective To investigate the clinical value of different magnetic resonance (MR) pulse sequences in diagnosis of spinal metastatic tumor. Methods Fifteen patients with clinically suspected spinal metastatic tumor were included in this study. These patients were with documented primary tumors. Four MR pulse sequences, T1-weighted spin echo (T1WI SE), T2-weighted fast spin echo (T2WI FSE), short time inversion recovery (STIR), and gradient echo 2-D multi echo data imaging combination (GE Me-2D) were used to detect spinal metastasis. Results Fifteen vertebral bodies were entire involvement, 38 vertebral bodies were section involvement, and totally 53 vertebral bodies were involved. There were 19 focal infections in pedicle of vertebral arch, 15 metastases in spinous process and transverse process. Fifty-three vertebral bodies were abnormal in T1WI SE and GE Me-2D, 35 vertebral bodies were found abnormal in T2WI FSE, and 50 vertebral bodies were found abnormal in STIR. The verges of focal signal of involved vertebral bodies were comparatively clear in T1WI SE, comparatively clear or vague in T2WI FSE, vague in STIR, and clear in GE Me-2D.Conclusions GE Me-2D may be the most sensitive technique to detect metastases. So three sequences (T1WI SE, T2WI FSE, GE Me-2D) can demonstrate the early changes of spinal metastasis roundly.
文摘目的探讨三维梯度自旋回波(GRASE)序列在老年患者磁共振胆胰管成像(MRCP)中的应用价值。方法纳入MRCP检查的老年患者63例。同时采集屏气2D-FSE、屏气3D-GRASE和呼吸触发3D-FSE序列。计算图像的信噪比、对比噪声比和对比度,并对图像质量进行主观评价,包括伪影、背景抑制、总体图像质量和胆胰管各分支的显示情况。组间比较采用单因素ANOVA检验或非参数Kruskal-Wallis检验。结果GRASE序列的伪影评分高于2D-FSE序列,差异具有统计学意义(4.24±0.69 vs 3.76±1.03,P<0.05),但与3D-FSE序列之间差异无统计学意义(P>0.05)。GRASE序列背景抑制的评分高于2D-FSE序列(P<0.05)。在图像的总体质量评分中,GRASE序列略高于3D-FSE序列,差异无统计学意义(4.29±0.83 vs 4.16±0.79,P>0.05),两者均高于2D序列,差异均有统计学意义(P<0.05)。GRASE序列的CNR、CR与3D-FSE序列相近,差异无统计学意义(P>0.05),均高于2D-FSE序列,差异均有统计学意义(P均<0.05)。GRASE序列在胆总管、肝总管、右肝管后支、左肝管内、外支的显示的显示能力与3D-FSE序列无差别。GRASE序列在右肝管前支的显示能力不如3D-FSE序列(P<0.05)。结论GRASE获得胆胰管的图像质量与3D-FSE序列接近,高于2D-FSE序列,为老年人疾病诊断提供影像学依据。
