CTMRI原理

CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYCT基本知识长征医院影像科王俭63610109-73658(0)、73675(MRI)、73655(CT)CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY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CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY二、CT值（HU）、窗宽（ww）、窗中心（wc）CT20层次2000层次（HU）CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY三、部分容积效应CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY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CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY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1~n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1~5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CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY螺旋CT工作原理CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY不同CT技术比较CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY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CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYLung4D-CTCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY3D-CTCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYTargetScanCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYHighResolusionCTScan（HRCT）CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY支气管内膜结核（CTVE）CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY心脏CT-3DCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY曲面成像：冠状动脉拉直HCC：CTAresonstructionHCC、HHE脾动脉动脉瘤门静脉高压，侧枝循环CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY腹腔动脉支架三维重建CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY颈部血管三维重建CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY动脉粥样硬化CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY循环系统4D-CTCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY4D-CTAAngiographyCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYDynamicCTscanArteryPeriodAPPortalPeriodPPDelayPeriodDPCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYPortalSystem4D-CTCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY肩关节三维重建CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY面骨发育畸形CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY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)CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYMRI基本构成NS主磁场射频场CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYMRI工作原理CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY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CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY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≈TR×T2/TE×T1CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYMRI信号含义(中低场)信号程度T1WIT2WI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CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY不同组织MRI信号特点(中低场)分类代表组织T1WIPDWIT2WI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CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYMRI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CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY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？CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYmovementartifactCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY主动脉搏动伪影CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY磁场不均匀伪影CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYMetalartifactCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY融合图像断层（FIT）：CT-SPECTCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITYMagneticResonanceAngiography(MRA)CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY大动脉炎：右锁骨下动脉狭窄CHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY胆总管结石：MRCPCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY输尿管肿瘤：MRUCHANGZHENHOSPITALTHESECONDMILITARYMEDICALUNIVERSITY本课重点1、CT值？2、窗宽？3、窗中心？4、部分容积效应？