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第四章_ 磁共振成像检查技术(第二节课)课件

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第四章_磁共振成像检查技术(第二节课)课件
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Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 磁共振检查技术 二 吴永峻 广东医学院放射诊断教研室 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 上节课重点复习内容 1 SE及FSE序列中哪些参数决定T1及T2 PD加权 2 为什么IR序列可获得重T1WI 3 GRE序列哪些参数决定T1及T2 PD加权 4 T1时间 T2时间 TR及TE时间 T1WI T2WI PDWI Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 第二节 成像参数的选择 一 与图像质量有关的成像参数 1 信噪比 SNR 2 对比噪声比 contrast to noise ratio CNR 3 空间分辨率 4 扫描时间 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 一 与图像SNR 信噪比 有关的主要成像参数 MRI信号 S 净磁矢量在横向平面进动时在接收线圈 内感应出的电流 噪声 N 来源 磁体内患者的体质结构 检查部位和 设备系统固有的电子学噪声 1 质子密度影响 2 体素大小的影响 3 TR TE和翻转角度 4 NEX 回波次数 5 接收带宽 6 线圈类型 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial TR时间 TE时间 回波 单 次数 接收带宽 扫描野 FOV 层厚 层距 层数 扫描时间 距阵 回波次数 成像参数选择 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 质子密度低的区域如致密骨 肺仅能产生低信号 因 而SNR低 质子密度高的区域如脑 软组织能产生高信号 故SNR高 1 质子密度的影响 SNR Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial T1加权 T T2 2 加权加权 骨的质子密度低 产生低信号 SNR低 脑组织的质子密 度高 产生高信号 SNR高 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 2 体素大小的影响 1 与SNR成正比 体素 FOV 层厚 像素 2 与SNR成反比 矩阵 160 160 192 192 256 256 容积较大的体素所含质 子数量比容积较小的体 素多 因而SNR高 SNR Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial FOV对图像SNR的影响 SNR T1WI FOV 24 18cm 矩阵 320 224 NEX 2 层厚6 0mm 空间分辨力相对较低 而图像SNR相 对较高 同一病人T1WI FOV 16 16cm 矩阵 NEX 层厚同a 空间分辨力相对较 高 而图像SNR相对较低 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 矩阵对图像SNR的影响 SNR T1WI 矩阵512 256 FOV24 18cm NEX 1 层厚6 0mm 体素容积较小 空间分辨力相对较高 而SNR相对较低 图像粗糙 T1WI 矩阵256 128 FOV NEX 层 厚同a 体素容积较大 空间分辨力 相对较低 而SNR相对较高 图像较 细腻 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 3 TR TE和翻转角的影响 SNR 增加TR SNR升高 减少TR SNR下降 增加TE SNR下降 减少TE SNR升高 翻转角度为90 时 产生的信号量最大 SNR最高 反 之 角度越小 产生的信号量越少 SNR越低 1 TR对SNR的影响 2 TE对SNR的影响 3 翻转角度对SNR的影响 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial SNR TR对SNR的影响 SET1WI TR 560ms TE 20ms 扫描时间 1分41秒 SET1WI TR 240ms TE 20ms 扫描时间 1分31秒 增加TR SNR升高 减少TR SNR下降 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial SNR TE对SNR的影响 增加TE SNR下降 减少TE SNR升高 Image A TE 423 msImage B TE 740 msImage C TE 1199 ms Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial SNR 翻转角对SNR的影响 翻转角度为20 时 SNR 相对较低 图像粗糙 翻转角度为85 时 SNR 相对较高 图像较细腻 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial SNR 4 NEX对SNR的影响 NEX 1 SNR下降 扫描时间 1分24秒 NEX 4 SNR增加1倍 但 扫描时间增加4倍 扫描时间 5分11秒 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 5 接收带宽对SNR的影响 SNR 接收带宽 20 8KHZ SNR下降 接收带宽 6 9KHZ SNR增高 接收带宽减少到一半 SNR增加40 时间延长1倍 增加化学位移伪影 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 单通道头部线圈 SNR降低 6 线圈类型的影响 SNR 8通道头部线圈 SNR升高 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 二 CNR 对比噪声比 CNR 是指图像中相邻组织 结构间SNR的差异性 CNR SNR A SNR B 低对比分辨力 图像中可辨认的信号强度差别的最小极 限 影像因素 1 脉冲序列和成像参数 TR TE TI FA 2 NEX 体素 接受带宽 线圈类型 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 灰质 白质 脑脊液 CNR Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 三 空间分辨率 概念 图像中可辨认出相邻空间关系的最小物体的几何 尺寸 既对细微结构的分辨力 影像因素 1 体素小 空间分辨率高 2 层厚薄 空间分辨率高 3 FOV一定 矩阵越大 体素小 空间分辨率高 4 矩阵一定 FOV越小 空间分辨率高 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial FOV对图像空间分辨力的影响 空间分辨力 T1WI FOV 24 18cm 矩阵 320 224 NEX 2 层厚6 0mm 空间分辨力相对较低 而图像SNR相 对较高 同一病人T1WI FOV 16 16cm 矩阵 NEX 层厚同a 空间分辨力相对较 高 而图像SNR相对较低 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 矩阵对图像空间分辨力的影响 T1WI 矩阵512 256 FOV24 18cm NEX 1 层厚6 0mm 体素小 空间分 辨力相对较高 而SNR相对较低 图像 粗糙 T1WI 矩阵256 128 FOV NEX 层 厚同a 体素大 空间分辨力相对较 低 而SNR相对较高 图像较细腻 空间分辨力 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 四 扫描时间 概念 完成数据采集的时间 如SE序列 扫描时间 TR 相位编码次数 NEX Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial NEX对扫描时间的影响 NEX 1 SNR下降 扫描时间 1分24秒 NEX 4 SNR增加1倍 但 扫描时间增加4倍 扫描时间 5分11秒 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 二 成像参数的选择 图像质量与成像参数 选择参数选择参数不利影响不利影响 最佳最佳SNRSNRNEXNEX 矩阵矩阵 层厚层厚 接受带宽接受带宽 FOVFOV TRTR TETE 扫描时间扫描时间 空间分辨力空间分辨力 空间分辨力空间分辨力 最短最短TETE 化学位移伪影 化学位移伪影 空间分辨力空间分辨力 T1T1加权加权 T2T2加权加权 最佳空间分辨力最佳空间分辨力 方形 方形FOVFOV 层厚层厚 矩阵矩阵 SNRSNR 扫描范围 扫描范围 SNRSNR 扫描时间 扫描时间 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 选择参数选择参数不利影响不利影响 最短扫描最短扫描 时间时间 FOVFOV TRTR 相位编码次数相位编码次数 NEXNEX 容积采集层数容积采集层数 SNRSNR 扫描范围 扫描范围 包裹伪影包裹伪影 SNRSNR 成像层数 成像层数 空间分辨力空间分辨力 SNRSNR SNRSNR Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial NEX 2 矩阵448 256 扫描时间 2分钟 头部为信号较强的部位腹部为信号较弱的部位 NEX 4 矩阵384 192 扫描时间 3分18秒 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 第三节 流动现象的补偿技术 一 流动状态的主要类型 1 层流 规律 稳定的流动状态 管腔中心流速快 贴管壁处流速相对较慢 2 紊流 又称湍流 无规律的流动状态 含多种不同方向且流速随机波动的 流动成分 3 涡流 层流经管腔狭窄处时产生的一种流动状态 狭窄处速加快 而在狭 窄后管壁处呈漩涡状流动 4 滞流 停滞或极慢的流动 层流层流 紊流 狭窄 涡流 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 二 流动现象 血流和脑脊液的流动状态在MRI产生的效应 1 时间飞越 time of flight TOF效应 流动质子 流体 在成像过程中 因流入或流出成像容积而引起其信号强度改变 1 流空 flow viod 又称高流速信号缺失 指快速流动的质子在成像层 面内受到RF激励 但在相位重聚前流出成像层面 因而无信号产生 在影像 上表现为管腔内信号缺失而呈黑影 SE序列 TE越长 层面越薄则高流速信号缺失越明显 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 流空效应 动静脉流空效应 FSE序列 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial FSE序列 显著 流空效应 GRE序列 不显著 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 二 流动现象 1 时间飞越 2 进入现象 又称流动相关增强 指成像层面内静止质子受到RF脉冲反复激励 后趋于饱和 信号变弱 而垂直流入成像层面未曾受到过激励的 新鲜 质子 在成像层面内受到激励并经历相位重聚后 则可产生比周围静止质子信号强 度更高的的信号 并在进入成像层面的第一层时最显著 长TR 薄层面 流速快 流动方向与层面选择方向相反时 流动相关增强显著 成像体积内静止的质子被饱和 显示低或无信号 流动的质子通过成 像体积 未被饱和 产生信号 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 腹部扰相GRE T1WI横断面从上往下 腹主动脉信号从强到弱 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 二 流动现象 2 体素内相位离相 在同一体素内同时含有流动质子和静止质子或流动 质子间速度 方向不一致时 则体素内质子间将出现相位差 层流引起 的去相位可补 紊流引起的去相位则不能补偿 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 流入增强效应 GRE序列 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial FSE T2WI 血流为低信号FSE T1WI 血流为高信号 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 流动运动伪影 重像伪影搏动伪影 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 三 流动现象的补偿 1 梯度磁距重聚相位 静脉和较小动脉内的血流 2 预饱和 血流和脑脊液显示为低信号的T1WI及 PDWI 3 偶数回波重聚相位 用于T2WI Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 梯度磁矩重聚相位 重像伪影 大血管搏动 增强动脉期 补偿方法 改变相位编 码方向 加心电门控 增强门脉期 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 预饱和 2D TOF MRV3D TOF MRA Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 肝右叶癌并发 门脉癌栓 血管造影显示门脉与肿瘤的关系 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 第四节 伪影的补偿技术 1 运动伪影 2 包裹伪影 3 化学位移伪影 4 化学性配准不良伪影 5 截断伪影 6 磁敏感性伪影 7 拉链伪影 8 交叉激励 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 一 运动伪影 患者不合作 镇静 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 流动伪影 重像伪影 大血管搏动 增强动脉期 补偿方法 改变相位编码 方向 加心电门控 增强门脉期 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 呼吸运动伪影 补偿方法 加呼吸门控 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 二 混淆伪影或包裹伪影 包裹伪影补偿方法 增加FOV Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 三 化学位移伪影 补偿方法 增加接受带宽 预饱和技术 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 四 化学性配准不良伪影 补偿方法 使用SE序列 GRE序列选择适当的TE值 FIESTAFSE T2WI Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 五 截断伪影 矩阵256 128 皮层区明暗相间的弧 形伪影 补偿方法 增大矩阵512 256 皮层 区明暗相间的弧形伪影消失 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 六 磁敏感性伪影 金属伪影 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 七 拉链伪影 补偿方法 注意屏蔽 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 八 交叉激励 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 第五节 MRI对比剂的应用 一 增强机制 不成对的电子多 Fe4 Gd7 Mn5 磁矩大 1 顺磁性物质 Gd Mn GD DTPA T1缩短 2 超顺磁性物质 Fe SPIO T2 T2 缩短 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 二 分类 一 生物分布性 1 细胞外对比剂 GD DTPA 血管内 细胞外间 隙 2 细胞内对比剂 SPIO 二 磁特性 1 顺磁性物质 GD Mn 2 超顺磁性物质 SPIO Fe Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 以肝脏为例 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial GD DTPA的应用 脑胶质瘤 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial GD DTPA的应用 肝动态增强 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 实时显示血管增强影像 GD DTPA的应用 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 灌注 成像 PWI GD DTPA的应用 Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial 网状内皮系统对比剂 SPIO的应用 肝细胞性肝癌 TSET2WISET1WI Gd TSET2WI SPIO TSET2WI SPIR SPIO Five weeks of practice ended in this way and my feelings can only be summed up in eight words although hard but very substantial Thank You
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