CT、MRI原理

CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,CT基本知识,长征医院影像科 王 俭 63610109-73658(0)、73675(MRI)、73655(CT),CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,一、CT基本原理,计算机,前准直器,后准直器,X线球管,探测器,储存、显示、胶片,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,二、CT值（HU）、窗宽（ww）、窗中心（wc）,CT,20层次 2000层次（HU）,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,三、部分容积效应,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,四、CT特点,断面成像密度成像解剖分辨率高射线损伤伪影增强扫描了解血液供应特点,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,五、CT发展简史,X线束 探测器 运动方式 扫描时间第一代 单射束 1n 平移+旋转 数分钟第二代 多射束 n数十 平移+旋转 18秒第三代 扇形束 数百个 旋转 15秒第四代 扇形束 环周 旋转 1秒左右第五代 扇形束 环周 旋转 亚秒级,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,螺旋CT工作原理,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,不同CT技术比较,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,螺旋CT、多排CT,特点： 速度快、图像好、射线少新功能： DCT、3D-CT、CTA、CTAP、 CTVE、HRCT、骨密度测定、 靶扫描,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,Lung 4D-CT,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,3D-CT,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,Target Scan,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,High Resolusion CT Scan （HRCT）,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,支气管内膜结核（CTVE）,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,心脏CT-3D,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,曲面成像：冠状动脉拉直,HCC：CTA resonstruction,HCC、HHE,脾动脉动脉瘤,门静脉高压，侧枝循环,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,腹腔动脉支架三维重建,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,颈部血管三维重建,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,动脉粥样硬化,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,循环系统4D-CT,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,4D-CTA,Angiography,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,Dynamic CT scanArtery Period APPortal Period PPDelay Period DP,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,Portal System 4D-CT,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,肩关节三维重建,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,面骨发育畸形,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,正常颅脑,MRI基本知识,长征医院影像科 王 俭 63610109-73658(0)、73675(MRI)、73655(CT),CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,MRI基本构成,N,S,主磁场,射频场,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,MRI工作原理,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,静止的质子，杂乱排列,主磁场作用下,质子规则排列,射频场终止,振动的质子释放能量,射频场作用下,质子进动、共振,计算机运算,磁共振图像,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,决定MRI信号的因素,小角度 T2WI大角度 T1WI,组织参数 T1值、T2值、质子密度(PD)、 流空效应扫描参数 TR、TE、翻转角 SI TRT2 / TE T1,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,MRI信号含义(中低场),信 号 程 度 T1WI T2WI极 低 信 号 骨皮质、水 骨皮质低/稍低信号 介于等信号和极低信号之间等 信 号 与背景实质脏器信号相仿高/稍高信号 介于等信号和极高信号之间极 高 信 号 脂肪 水、血管瘤,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,不同组织MRI信号特点(中低场),分类代表组织 T1WI PDWI T2WI硬组织 骨皮质、结石、肌腱、疤痕游离水 水肿、尿液、脑脊液 等信号结合水 实质脏器、肿瘤 等信号临界水 脓液、滑液 等信号 等信号脂肪 脂肪组织、黄骨髓 血液 依流动速度、存在形式、出血时间而异,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,MRI基本特点,优 点1、组织化学成像，敏感性高2、没有射线损伤、碘过敏危险，造影剂安全 系数大3、直接多轴面成像，可三维重建，加之功能 成像、水成像、血管成像等技术，信息量 大5、没有跳扫、漏扫问题6、由于原理不同，与CT有互补作用,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,缺 点 1、成像因素多，图像解释难 2、伪影（运动、化学位移、金属、系统.） 3、对钙化、结石不敏感 4、幽闭恐怖症 5、成像时间？ 6、假阴性、假阳性？,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,movement artifact,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,主动脉搏动伪影,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,磁场不均匀伪影,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,Metal artifact,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,融合图像断层（FIT）：CT-SPECT,CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,Magnetic Resonance Angiography ( MRA ),CHANGZHEN HOSPITAL THE SECOND MILITARY MEDICAL UNIVERSITY,大动脉炎：右锁骨下动脉狭窄,CHANGZHEN HOSPITAL T