【作者】 李亮；

【导师】 韩悦；

【作者基本信息】 天津医科大学 ， 影像医学与核医学， 2011， 硕士

【摘要】 第一部分直肠癌的MRI技术应用、平扫及动态增强表现目的探讨直肠癌合理的MRI扫描技术,总结其在MRI平扫及动态增强上的影像学表现,并探讨MRI动态增强检查在直肠癌诊断中的价值。材料与方法1.正常志愿者：30名健康志愿者行盆腔常规MRRI扫描,其中男性15名,年龄24-40岁,平均年龄29.4岁；女性15名,年龄22-26岁,平均年龄24岁。志愿者入选标准：身体健康,无直肠手术史,志愿者事先取得其知情同意后行盆腔MRI检查。2.解剖标本：选择7例健康尸体盆腔局部离断标本,男4例,女3例,其中1例男性尸体标本行常规MRI扫描。3.病例组：直肠癌49例,经活检病理证实直肠癌并行手术治疗,其中男28例,女21例,年龄49-85岁,中位年龄67岁。行常规、高分辨率及动态增强磁共振(DCE-MRI)扫描。纳入标准：未曾接受放、化疗且有完整MRI资料,并接受手术治疗者。排除标准：行盆腔放、化疗者。4.MR检查方法：采用GE 1.5T SignaLightspeed磁共振扫描仪,8通道相控阵线圈。范围从乙状结肠与直肠交界区(相当于腰5-骶1水平)至肛门。①正常志愿者：常规先行快速自旋回波(FSE)大视野T2WI矢状位,然后分别行轴位及冠状位常规T2WI、T1WI扫描。②尸体标本：由于离断尸体修块标本较小,我们选择了TORSOPA线圈对标本进行了扫描。扫描方式我们采用了和切片方式相吻合的轴位、矢状位及冠状位扫描,以保证扫描层面与切片方位的一致性。以FSE序列的T1WI及T2WI为主要扫描序列。切片标本、尸体MRI扫描图像与正常志愿者的MRI图像进行对比。③病例组：常规MR扫描与正常志愿者扫描方案一致。高分辨MR检查采用T2WI横断位,垂直于肿瘤所在直肠段的长轴,覆盖整个肿瘤,如肿瘤位于直肠下段,加做矢状位及斜冠状位,与肛管长轴平行。DWI扫描参数：TR/TE=2000/80ms,层厚、层间距及FOV与常规MRI相同。ETL=128。b值=1000s/mm2,弥散方向=3。动态增强磁共振检查,扫描序列应用3DF-SPGR序列。5.尸体标本制作1例男性离断的膀胱直肠区局部尸体标本用于MRI扫描,另外6例标本采用火棉胶包埋法对盆腔组织进行修块处理,应用切片机对修块处理后的局部盆腔组织进行切片,厚度为0.5mm,分别进行轴位、冠状及矢状位切割。6.术后标本术后标本沿着冠状面切开,保留肿物完整性。将标本用10%中性福尔马林液固定48 h后,石蜡包埋切片,HE染色,在普通光学显微镜下进行观察。评估肿瘤的最大侵润深度、淋巴结受累情况,环周切缘受侵情况。7.MRI图像分析①.正常健康志愿者及尸体标本MRI表现与尸体标本及解剖切片对照,确定直肠肠壁各层结构及系膜筋膜的影像学所见及其解剖学基础。②病例组所得结果与病理切片严格对照,总结直肠癌在MRI平扫及动态增强扫描中的表现,并分析MRI对其累及范围确定的准确性及对淋巴结转移评估的可靠性。③利用时间-信号强度曲线(TIC)对49例直肠癌患者的动态增强特点进行总结、分析,探求其表现特征及诊断价值。④测量方法及标准测量肿瘤边缘至邻近系膜筋膜最短距离(CRM),若肿瘤局限于直肠壁,测量肿瘤所在位置肠壁外缘至邻近系膜筋膜最短距离；若直肠系膜内有明显增大淋巴结、癌结节沉积或由肠壁突出迂曲索条影则测量它们距系膜筋膜的最短距离。侵犯邻近组织、器官距离计为零。根据Beets-Tan等研究标准：即在MRI上测量的最短距离<5mm与CRM<1mm高度相关,记为CRM(+),反之记为CRM(一)。测量肿瘤下缘,系膜内癌巢或增大淋巴结距肛缘距离在矢状位MRI上测量39例中下段直肠肿瘤距肛缘距离,并与利用硬质乙状结肠镜测量结果比较。8.统计学方法采用SPSS17.0软件进行统计学数据处理。对在矢状位MRI上和硬质乙状结肠镜两种方法测量肿瘤下缘距肛缘距离所得数据以均数±标准差(x±s)表示,采用配对t检验,以P<0.05为差异有统计学意义；对正常肠壁及直肠癌病灶达峰值时的信号强度(SImax),达峰值的时间(Tpeak),注入造影剂后前1min内最大的信号强度(SIlmin),早期增强率(SIR)数据以均数±标准差(x±s)表示,采用配对t检验,以P<0.05为差异有统计学意义。结果1.正常健康志愿者及尸体标本MRI所见与解剖切片的对照：①直肠壁的MR与解剖切片对照研究：解剖切片显示直肠壁由粘膜层、粘膜肌层、粘膜下层、固有肌层(深、浅肌层)及浆膜层(或包膜)构成。而MRI的T2WI仅能将直肠壁区分为二层结构,中心侧一圈高信号环,即粘膜及粘膜下层,和外周侧的低信号环,即固有肌层及包膜层。MRI仅能区分粘膜及粘膜下层与固有肌层及包膜层,不能区分粘膜与粘膜下层、深肌层与浅肌层、固有肌层与包膜层。另外,在T2WI上直肠壁最外缘常常见到不完整的线状极低信号影,常位于肠壁一侧,与编码方向有关,不是包膜而是化学位移伪影所致。②直肠系膜及直肠系膜筋膜的MR与解剖切片对照研究：直肠系膜在切片及尸体解剖上,直肠系膜位于直肠壁的周围,后方较厚,两侧次之,以脂肪组织为主,大体形状近似圆柱形,自上而下先是逐渐增宽,达肛提肌后贴于肛提肌内侧向下再逐渐变窄,其在MRI上表现为在T1WI、T2WI上均表现为直肠周围的脂肪信号。直肠系膜内系膜内可见弯曲条状血管、淋巴管及圆形、椭圆形血管断面影及淋巴结影,MRI表现为圆形或类圆形、索条状低信号。系膜筋膜在切片及尸体解剖上,直肠系膜筋膜是盆筋膜脏层环绕直肠系膜形成的边界清楚的薄层筋膜结构。在上方,直肠系膜筋膜于S3骶椎水平延续于乙状结肠系膜根部的结缔组织。在下方,直肠系膜筋膜延续于盆隔上筋膜表面的疏松结缔组织,末端与直肠壁紧贴,最后附着于肛提肌外缘,相当于尾骨尖前下方约2cm处。由于与直肠系膜及系膜筋膜外脂肪的存在,使之与直肠系膜筋膜形成天然对比,在TIWI及T2WI上均表现为环绕直肠系膜的线状低信号结构。在矢状位上由于直肠系膜筋膜末端与直肠壁紧贴,两者之间脂肪组织极少,加之1.5TMR空间分辨率限制,我们以尾骨尖端作为定位标志,以尾骨尖为起点,沿直肠走行方向向下测量至直肠壁2cm处,作为直肠系膜筋膜末端附着点。③扫描技术与范围FSE T2WI对于直肠肠壁、直肠系膜及直肠系膜筋膜均能够清晰的显示,是对筋膜结构显示效果最好的序列。在MRI上,为全程显示直肠系膜筋膜,轴位扫描范围自S1至肛缘；矢状位扫描范围位于双侧股骨头内侧缘两切线之间；冠状位扫描范围耻骨联合至骶骨后缘之间。矢状位扫描能显示直肠系膜末端病理改变,冠状位扫描范围包括盆腔淋巴结分布较多的髂血管分叉区,两者具有重要临床指导意义。2.病例组：①直肠癌的一般MR表现：49例直肠癌MRI所见与术中所见肿瘤位置及形态一致。肿瘤在T1WI上呈中等信号,T2WI呈等或混杂信号。高分辨率MRI扫描视野小,图像分辨率高,显示肿瘤侵犯范围清晰,判断较常规MRI准确率高,对直肠系膜筋膜显示更加清晰,显示其病理改变准确,对直肠系膜内淋巴结形态内部结构、血管断面及系膜内肿瘤周围病理改变显示更加确切、清晰。②直肠癌浸润范围的MR评价：按照肿瘤累计范围不同,其MR表现不同具体表现如下：一、肠壁增厚肠壁正常结构消失或肿瘤呈结节状向肠腔内突入,包膜连续性完整,与系膜内脂肪交界面规整；病理诊断17例,常规MRI正确判断13例,常规MRI+高分辨率MRI正确判断14例,常规MRI+高分辨率MRI+DCE-MRI正确判断15例；二、肿瘤突破肠壁,包膜层连续性中断,邻近直肠系膜内可见索条状、针刺状、片状及结节样低信号,侵犯直肠系膜筋膜者表现为直肠系膜筋膜信号增高或减低,局部增厚或内陷与肿瘤分界不清,肿瘤信号未突破筋膜；病理诊断26例,常规MRI正确判断21例,常规MRI+高分辨率MRI正确判断23例,常规MRI+高分辨率MRI+DCE-MRI正确判断24例；三、肿瘤穿透直肠系膜筋膜侵犯邻近组织器官表现,邻近组织器官正常信号消失；病理诊断6例,常规MRI正确判断5例,常规MRI+高分辨率MRI正确判断6例,常规MRI+高分辨率MRI+DCE-MRI正确判断5例。MR显示肿瘤局部侵润程度与病理结果存在差异,主要发生在判断肿瘤是否突破肠壁,部分MR显示突破肠壁肿瘤,病理结果为肿瘤周围炎性反应性增生。另外,MRI显示正常者,镜下病理可见肿瘤微转移。③MR对环周切缘状态的可靠性评估：术后病理结果显示CRM(+)20例,CRM(-)29例,MRI能正确判断45例,判定的总体准确度为91.8%(45/49),2例CRM(-)术前误判为CRM(+),2例CRM(+)术前误判为CRM(-)。④病变与肛缘距离的MR测量：在矢状位MRI上测量39例中下段直肠肿瘤(或癌巢、增大淋巴结)距肛缘距离,与硬质乙状结肠镜测量结果比较：MRI判断肿瘤下缘距肛缘的平均距离为6.36±0.91cm；硬质乙状结肠镜测量肿瘤下缘距肛缘平均距离为7.32±0.42cm。采用配对t检验,t值为4.35,P值为0.243,P>0.05,差异无统计学意义。⑤转移性淋巴结的MR评价：49例患者中无淋巴结转移31例,淋巴结转移18例。以淋巴结直径大于5mm、边缘不规整、内部信号不均匀为判断转移淋巴结的标准,常规MRI正确判断34例,常规MRI+高分辨率MRI正确判断39例,常规MRI+高分辨率MRI+DCE-MRI正确判断40例,常规MRI+DWI正确判断40例。转移性淋巴结MILI表现为T1W I高于肌肉信号,T2W I信号与肿瘤一致,转移淋巴结具体表现不同：最小直径3mm4例；最大直径15mmm3例；边缘不规整12例；内部信号不均匀14例；多发小点状低信号影,呈簇状分布3例；多个低信号结节影融合,边缘呈分叶状3例；DWI上呈高信号15例,其中2例呈高信号但病理诊断为非转移淋巴结,3例DWI呈低信号,但病理诊断为转移性淋巴结。直肠系膜内及盆腔内转移性淋巴结MRI表现各异,正常淋巴结、转移性淋巴结及反应性淋巴结增生在直径、形态及在DWI表现方面均有重叠,MRI表现相同。另外,对转移性淋巴结位置的确定具有重要意义,转移性淋巴结的位置决定环周切缘状态、能否行保肛手术。⑥直肠癌的DCE-MRI表现及其诊断价值：直肠癌MRI动态增强扫描49例。病灶多呈明显强化,边缘规整或不规整,部分病灶边缘呈结节状、小片状或分叶状,病灶内部强化程度均匀或不均；动态增强检查肠壁显示强化效应,但不能分辨肠壁各层,尤其粘膜及粘膜下层；对肿瘤的显示较平扫更加清晰,轮廓较平扫明显,但对肿瘤侵润程度范围判断准确性较平扫无明显提高,因为动态增强扫描不能分辨肠壁各层,另外,部分肿瘤周围炎性反应性增生或血管病变等也显示强化效应改变,因此对肿瘤侵润范围的判断准确性无明显提高。TIC曲线分为三种类型：A型-速升平台型；B型-速升后下降型,下降幅度大于10%；C型-持续上升型。直肠癌与正常肠壁组织TIC参数比较：直肠癌同正常直肠粘膜相比较,达峰值时的信号强度(SImax),注入造影剂后前lmin内最大的信号强度(SI1min)达峰值的时间(Tpeak),早期增强率(SIR)均高于正常直肠肠壁,SImax及SI1min、早期增强率P值小于0.05,存在统计学差异。肿瘤峰值时间(Tpeak)小于正常肠壁的峰值时间,两者之间存在统计学差异。小结1、1.5T MRI的T2WI仅能将直肠壁区分为二层结构,即粘膜及粘膜下层呈环状高信号,固有肌层及包膜层呈环形低信号。直肠系膜筋膜在T1WI及T2WI上均可显示,表现为环绕直肠系膜的线状低信号结构。MRI能全程显示直肠系膜筋膜。2、常规FSE T2WI结合高分辨率MRI对直肠肠壁、直肠系膜及直肠系膜筋膜、判断肿瘤侵犯范围显示效果最好的序列,DWI序列是判断转移淋巴结的重要扫描序列。轴位全程显示直肠系膜筋膜的扫描范围自S1至肛缘,矢状位扫描范围为双侧股骨头内侧缘两切线之间,冠状位为耻骨联合至骶骨后缘之间。矢状位MRI扫描,提供直肠系膜末端及邻近组织结构解剖及病理改变的信息。3、1.5T MRI能确切显示直肠肿瘤位置、形态,对肿瘤局部侵润程度显示与病理结果存在差异,主要发生在肌层侵犯深度及肿瘤是否突破肠壁的判断上。4、1.5T MRI在判断环周切缘状态具有重要临床应用价值,在诊断直肠系膜内及盆腔内转移性淋巴结方面存在困难,在保肛手术可行性方面,矢状位MRI对判断断直肠癌肿瘤下缘距肛缘的距离具有很好的预测价值,并且通过对直肠系膜末端及周围结构的评估,指导临床制定合理的治疗方案。5、DCE-MRI不仅能显示病变的形态特征,还能较全面描述对比剂进入和排出肿瘤的血流动力学过程,反映病灶局部的血液循环情况,但不能分辨直肠壁各层。第二部分MRI不同成像方式对直肠癌术前分期价值的初步研究目的评价磁共振常规MRI、常规MRI+高分辨率MRI,常规MRI+高分辨率MRI+DCE-MRI及常规MRI+DWI四种检查方式对直肠癌术前T,N分期的可靠性,探讨直肠癌局部分期(T、N)最佳MRI扫描序列组合。材料与方法1.研究对象与第一部分病例组资料一致。2.检查手段及MRI参数与第一部分内容一致。将MRI检查所得结果与病理切片严格对照。术后标本病理学按照2003版美国肿瘤联合会(AJCC)和国际抗癌联盟(UICC)直结肠癌的病理标准,结合2003版美国肿瘤联合会(AJCC)和国际抗癌联盟(UICC)直结肠癌的病理标准,直肠癌MRI影像学分期标准为：T1肿瘤局限于粘膜层。T2肿瘤累及肌层。T3肿瘤累及浆膜层,或穿透浆膜层,累及肠周组织,肠周脂肪间隙模糊,肠管外膜面出现结节影及条索影。T4肿瘤侵及盆壁及临近器官。N0无淋巴结转移。N1肠周1-3枚淋巴结转移,N2肠外4枚及4枚以上淋巴结转移。淋巴结侵犯淋巴结受累定为淋巴结的最短径大于5mm,边缘不规整,内部信号混杂。3.将49例患者MRI图像按不同序列组合分成四组,即常规MRI、常规MRI+高分辨率MRI、常规MRI+高分辨率MRI+DCE-MRI三组用于T、N分期评估,常规MRI+DWI仅用于N分期评价。由两位工作5年以上的腹部影像诊断医师采用双盲法进行阅片,分别对前三种序列组合方式所得图像进行术前分期(T、N),对常规MRI+DWI所得图像仅进行N分期。以术后病理分期作为金标准,来评价四种检查方法T、N分期的准确性。4.统计学处理采用统计软件SPSS17.0,计算四种序列组合检查方式T、N分期准确性,并与术后病理结果进行一致性检验,若Kappa值小于0.45,说明一致程度很差,若Kappa0.45-0.7说明一致性中等,可进行一般性评估,Kappa值大于0.7,说明一致程度很好。结果常规MRI、常规MRI+高分辨率MRI,常规MRI+高分辨率MRI+DCE-MRI三种MRI扫描方式对直肠癌T分期准确度分别为79.6%、87.8%、89.8%,与术后病理结果一致性比较Kappa值分别为0.650、0.790、0.824；常规MRI、常规MRI+高分辨率MRI,常规MRI+高分辨率MRI+DCE-MRI及常规MRI+DWI四种检查方式对直肠癌术前N分期的准确度分别为69.4%、79.6%、81.6%、81.6%,与术后病理结果一致性比较Kappa值分别为0.452、0.616、0.665、0.666。三种不同序列组合对直肠癌T分期准确度及Kappa值如下：常规MRI常规MRI+高分辨率常规MRI+高分辨率MRI MRI+DCE-MRI准确度79.6%87.8%89.8%Kappa值0.650 0.790 0.824四种不同序列组合对直肠癌N分期准确度及Kappa值如下：常MRI常规MRI+高分辨常MRI+高分辨常规MRI+DWI率MRI率MRI+DCE-MRI准确度69.4% 79.6% 81.6% 81.6%Kappa值0.452 0.616 0.665 0.666结果表明对于T分期,常规MRI+高分辨率MRI,常规MRI+高分辨率MRI+DCE-MRI这两种序列准确性较高,对于N分期,常规MRI+高分辨率MRI+DCE-MRI及常规MRI+DWI这两种序列准确性较高。MRI T分期存在高估和低估,本组病例显示高估是由于由于一些炎症、感染和血管病变,造成肠壁及其周围结构产生类似肿瘤侵润的征象,导致过度分期。低估是由于直肠系膜内的肿瘤微转移,在MRI上不能确切显示,导致分期不足。动态增强检查不能分辨肠壁各层,尤其粘膜粘膜及粘膜下层,另外部分肿瘤周围炎性反应性增生或血管病变等显示强化效应改变,产生类似肿瘤侵润征象。因此对肿瘤T、N分期准确性无明显提高。小结：1、常规MRI+高分辨率MRI+DWI这种序列组合是目前直肠癌MRI局部分期(T、N)的最佳序列组合。常规MRI+高分辨率MRI T分期准确率达87.8%,常规MRI+DWI N分期准确率达81.6%。2、对直肠癌进行N分期时,不仅要判断淋巴结数目,还应运用不同扫描方位MRI图像,判断淋巴结的空间位置,了解其与直肠系膜筋膜相对位置,尤其运用矢状位图像,了解直肠系膜末端淋巴结转移情况。3、DCE-MRI不能提高直肠癌T、N分期准确度。结论1、常规MRI+高分辨率MRI+DWI这种序列组合是目前直肠癌MRI局部分期(T、N)的最佳扫描序列组合。2、1.5T MRI在判断环周切缘状态及肿瘤下缘距肛缘距离方面具有重要临床应用价值,但在判断转移性淋巴结方面有一定限度。3、矢状位T2WI能全程显示直肠系膜筋膜、判断肿瘤下缘距肛缘距离、确定直肠系膜末端病理改变,在直肠癌手术治疗中具有重要的临床应用价值。4、MRI对直肠癌T分期具有较高准确性,达87.8%,对N分期准确性偏低,达81.6%。5、DCE-MRI不能提高直肠癌T、N分期准确度。更多还原

【Abstract】 Objective:To explore rectal cancer reasonable MRI scan technology, summarizes its in MRI and DCE-MRI the imaging findings, and assess the value of DCE-MRI in the preoperative staging of rectal cancer.Materials and Methods:1. Normal volunteers:30 health volunteers’ the pelvic scan were imaged with routine MRI examination, each gender have 15 people. The average age of male people is 29.4, the femal people is 24. All of the volunteers were without operation of colon and rectum history. All the volunteer were admitted to have the MRI scan.2. Anatomical specimens:Seven speciments of cadaver pelvic,4 males and 3 females.1 received the routin examination.3. Case group:49 patients of rectal carcinoma were preoperatively assessed by routin MRI, high resolution and DCE-MRI with a phased array coil. The male 28 patients,female 21 patients, median age 67. Inclusion criteria:Never accept radiotherapy or and chemotherapy and have complete MRI material, and surgery healers. Exclusion criteria:acceptance the pelvic radiotherapy or and chemotherapy.4. MR scan was performed on GE 1.5 T signa scanner with phased array coil. Scan range from the sigmoid colon and rectal border area (L5-S1) to the anus.Compare the distance which measurement methods between in sagittal MRI and postoperative measurement MRI inferior margin from anus distance, using matching t test, P<0.05 for difference have statistically significant; On the normal bowel wall and rectal lesions to the signal intensity (SImax), peaked time (Tpeak), within the first 1 min injection of contrast the biggest signal strength (Sl1min), early increase rate (SIR) data, using matching t test, P<0.05 for difference have statistical significance. Results:1.①Rectum wall By the rectal wall anatomy biopsy showed mucosal layer, muscularis mucosa, submucosa, muscularis propria.And serosal layer (or coating) composition. The T2WI MRI of the rectum is divided into only two-story structure, the center side of the circle of high signal ring, that is, mucosa and submucosa, and peripheral side of the low signal ring, that is, the muscularis propria and the coating layer. MRI can only distinguish the mucosa and submucosa and muscularis propria and the coating layer, can not distinguish between mucosa and submucosa; muscularis propria and the coating layer. In addition, the outer edge of the rectal wall on T2WI often see incomplete linear low signal intensity, often located in the side wall, and the direction of the relevant code, but not the capsule due to chemical shift artifact.②Mesorectum In the biopsy and autopsy, the mesorectum is located around the rectum, behind the thick, on both sides of the second, mainly to adipose tissue, generally cylindrical shape similar to, first, gradually widened from top to bottom, of the levator ani Affixed to the levator ani muscle after the muscle and then gradually narrow down the inside of their performance in the MRI, in TIWI, T2WI showed on both perirectal fat signal. Mesorectum department of membrane bending strip visible blood vessels, lymph vessels, and round, oval, film and lymph vessels video section, MRI showed round or oval, low signal cable strip.Mesorectal fascia In biopsy and autopsy, mesorectal fascia is the visceral pelvic fascia, formed around the mesorectal fascia clear boundary layer structure. In the above, mesorectal fascia at the level of S3 sacral roots extend to the sigmoid colon mesentery connective tissue. In the following, mesorectal fascia, the fascia extend across the surface of the basin of loose connective tissue, close to the end with the rectal wall, and finally attached to the outer edge of the levator ani, the equivalent of about 2cm below the coccyx at the tip of the former. In MRI, the whole show mesorectal fascia, axial scanning range from S1 to the anus; sagittal scanning range in the femoral head between the medial border of the two tangent; coronal scanning range of the pubic symphysis to the posterior margin of the sacrum Between;. As with the mesorectal fascia and mesangial outside the presence of fat, so that the formation of natural and mesorectal fascia contrast, in the performance on both T2WI TIWI and around the mesorectum as linear low signal structure. In the sagittal end of the mesorectal fascia and the rectal wall close, very little fat between the two, combined with limited spatial resolution 1.5TMR, our cutting-edge as a location mark the coccyx to the coccyx tip as a starting point, along the rectum Traveling down the measure to the direction of 2cm at the rectal wall, as the end of mesorectal fascia attachment.2.①MRI scan showed 49 cases of colorectal tumor exact location, shape; tumor showed intermediate signal signal T1WI, T2WI showed equal or slightly higher signal. MR form and position of the tumor with surgery and pathology results are consistent.②The extent of tumor invasion by the order from light to heavy divided into the following four signs:Tumor signal confined to the intestinal wall, fat and intestine week structured interface; tumor intestinal wall into the mesorectal signal a breakthrough, the wall can be seen outside the bar cable video, film -Like and nodular low signal; tumor signal violations mesorectal fascia, adjacent tissues and organs were normal signal change; tumor signal violations through mesorectal fascia adjacent tissues and organs. MR showed the extent of local tumor invasion and pathological results were different, to determine whether the tumor is the major breakthrough occurred in the intestinal wall, part of the break wall MR showed the tumor, pathological results for the inflammatory reaction around the tumor proliferation.③Pathology results showed that CRM (+) 20, CRM (-) 29, MRI can correctly judge the 45 cases to determine the overall accuracy of 91.8%(45/49),2 cases of CRM (-) before surgery error Sentenced for the CRM (+),2 casesCRM (+) before surgery mistaken for CRM (-).④The lower edge of the tumor, the Department of membrane lymph node cancer nest or increase the distance from the anal verge measured on sagittal MRI measurement of 39 cases on the middle and lower rectal tumor distance from the anal margin, the results compared with the pathological measurements:MRI to determine tumor From the anal margin of the lower edge of the average distance of 6.36± 0.91cm; after the lower edge of the tumor measured the average distance from the anal margin of 7.32±0.42cm. Paired t test, t value 4.35, P value of 0.243, P> 0.05, the difference was not statistically significant.⑤metastatic lymph nodes within the mesorectum and pelvic lymph node metastatic performance of different MRI, normal lymph nodes, metastatic lymph nodes, and reactive lymph node hyperplasia in diameter and shape, are overlapping in the performance of DWI, MRI the performance of the same. In addition, metastatic lymph nodes is important to determine the location of metastatic lymph nodes on the position of circumferential resection margin status, whether the line of sphincter preserving surgery.⑥DCE-MRI:Dynamic contrast-enhanced MRI scan Cancer 49 cases. Lesions were mostly significantly enhanced, regular or irregular edges, some edge of nodular lesions, small pieces or lobulated, homogeneous degree of enhancement within the lesions or uneven. Dynamic enhanced MRI showed enhancement effect of the intestinal wall, but can not distinguish between the intestinal wall layers, especially in mucosa and submucosa. Shows the tumor more clearly than the plain, outline, plain more apparent. However, the extent of tumor invasion to determine the accuracy of the range was no significant increase compared with plain, because the dynamic contrast-enhanced scans can not distinguish between the intestinal wall layers, In addition, some inflammatory reaction around the tumor or vascular lesions such as hyperplasia also showed enhanced effects of change, so Determine the scope of tumor invasion was no significant increase accuracy.TIC curve is divided into three types:A type-speed lift platform type; B-type-type of fast down hill; C type-rise type. Cancer and normal the intestinal wall tissue compared TIC parameters:rectal cancer compared with normal mucosa, reaching peak signal intensity (SImax), after injection of contrast agent before the lmin the largest signal strength (SI1min) peak time (Tpeak), the early enhancement ratio (SIR) were higher than those of normal rectal the intestinal wall, SImax and SI1min, early enhancement rate P value less than 0.05, there are statistically significant. Tumor peak time (Tpeak) less than the normal peak time of the intestinal wall, there is significant difference between the two. Summary:1.1.5T MRI the T2WI divided the rectum wall into two-layer structure, which ring the mucosa and submucosa showed high signal, the inherent circular muscular layer and coating layer showed a low signal. Can not distinguish between mucosa and submucosa, muscularis propria and the coating layer. Mesorectal fascia in TIWI and can be displayed on T2WI, showing around the mesorectum linear low signal structure. MRI can be fully displayed mesorectal fascia.2. FSE T2WI is the best sequence to show the rectal the intestinal wall, the mesorectum and mesorectal fascia. Axial shows mesorectal fascia throughout the scanning range from S1 to the anal verge, sagittal scan range of femoral head between the medial border of the two tangential or coronal to the pubic symphysis to sacrum between the posterior edge. Sagittal MRI scans, providing the end and the adjacent mesorectal anatomy and pathological changes in the organizational structure of information.3. The neoplasms exact location, shape, degree of local tumor invasion can be shown by 1.5TMR, and between the degree of local tumor invasion on MRI and pathological results show differences, to determine whether the tumor is the major breakthrough occurred in the the intestinal wall.4.1.5T MRI in determining the status of circumferential resection of the original has important clinical value in the diagnosis of mesorectum and pelvic lymph node metastases exist difficulties in the feasibility of sphincter preserving surgery, sagittal MRI of rectal cancer to determine the next off The distance from the anal margin edge has a good predictive value, and by the end of the mesorectum and the assessment of surrounding structures, clinical specify a reasonable treatment.5. DCE-MRI can show not only the morphological characteristics of lesions, but also a more comprehensive description of contrast agent to enter and discharge dynamic processes of tumor blood flow, reflecting the focus of local blood circulation, but can not distinguish between the rectal wall layers. Objective:To evaluate routine MRI, routine MRI+high-resolution MRI, routine MRI+high-resolution MRI+DCE-MRI and routine MRI+DWI four inspection methods i reliability in preoperative T, N stage of rectal carcinoma, explore the local staging of rectal cancer (T, N) the best combination of MRI scan sequence.Materials and Methods:1. Study information with the first part of the same patient group.2. Inspection means and the first part of MR parameters and consistent.3. The 49 patients in different series combination of MRI images into four groups, namely, routine MRI, routine MRI+high-resolution MRI, routine MRI+ high-resolution MRI+DCE-MRI for the three groups T, N stage assessment, routine MRI+DWI Only for N staging evaluation.5 years of work by two or more physicians diagnose abdominal imaging method using double-blind review films, respectively, from the four combinations of image sequences preoperative staging (T, N), on routine MRI+DWI N points from the image Period. To the pathological staging as the gold standard, the four inspection methods to evaluate the T, N staging accuracy.4. Statistical analysis using statistical software SPSS 17.0, calculating inspection methods combinations of four sequences of T, N staging accuracy and consistency of the results with the pathological examination, if the Kappa value is less than 0.45, indicating the degree of consistency is poor, if Kappa0.45-0.7 shows moderate consistency can be a general assessment, Kappa values greater than 0.7, indicating a good degree of consistency.Results:Routine MRI, routine MRI+high-resolution MRI, routine MRI+ high-resolution MRI+DCE-MRI scan of three MRI T staging accuracy of rectal cancer were 79.6%,87.8%,89.8%, consistent with the pathological Comparison of Kappa values were 0.650,0.790,0.824; routine MRI, routine MRI+high-resolution MRI, routine MRI+high-resolution MRI+DCE-MRI and routine MRI+DWI inspection methods on the four preoperative N staging of rectal cancer Accuracy was 69.4%,79.6%,81.6%,81.6%, compared with postoperative pathologic findings consistent Kappa values were 0.452,0.616,0.665,0.666. The results show that for T staging, conventional MRI+high-resolution MRI, routine MRI+high-resolution MRI+DCE-MRI sequences of these two high accuracy for N staging, conventional MRI+high-resolution MRI+DCE-MRI and routine MRI+DWI higher accuracy of the two sequences. MRI T staging of overvalued and undervalued, this group of patients showed over-due for some inflammation, infection and vascular disease, resulting in the intestinal wall and surrounding structures produce similar signs of tumor invasion, leading to over-staging. Underestimated because of the tumor within the mesorectum micrometastases, can not exactly show the MRI, leading to inadequate staging. Dynamic enhanced MRI can not distinguish between layers of the intestinal wall, mucosa and submucosa mucosa in particular, the other part of the inflammatory reaction around the tumor or vascular lesions such as hyperplasia showed strengthening effect change, produce similar signs of tumor invasion. Therefore, the tumor was no significant increase the accuracy of T staging.Summary:1. Routine MRI+high-resolution MRI+DWI sequence combination that is the local staging of rectal cancer MRI (T, N) the optimal sequence alignment. routine MRI+ high-resolution MRI T staging accuracy rate of 87.8%, conventional MRI+DWI N staging accuracy rate of 81.6%.2. For N staging of rectal cancer, not only to determine the number of lymph nodes, but also the use of MRI images of different scanning position to determine the spatial location of lymph nodes, to understand their relative position with the mesorectal fascia, especially the use of sagittal images, understand the mesorectum End of the lymph node metastasis has important clinical significance.3. DCE-MRI does not improve cancer T, N stage 1. Routine MRI+high-resolution MRI+DWI sequence combination that is the local staging of rectal cancer MRI (T, N) the optimal sequence alignment.2.1.5T MRI the T2WI divided the rectum wall into two-layer structure, the mucosa and submucosa, muscularis propria and the coating layer, can not distinguish between mucosa and submucosa, muscularis propria and the coating layer. Circumferential resection margin in determining the original state has an important clinical value. In determining the metastatic lymph nodes as being difficult.3. Sagittal T2WI mesorectal fascia can be fully displayed, the lower edge of the tumor to determine the distance from the anal margin, while also using sagittal MRI shows mesorectal anatomy and pathological changes of the end of the surgical treatment of rectal cancer has important clinical value.4. MRI of rectal carcinoma with high accuracy, T stage of N staging accuracy is low.5. DCE-MRI does not improve cancer T, N stage.更多还原