1、左上图:白箭头直肠筋膜,黑箭头Denonvillier fascia,右图:直箭肛提肌,箭头耻骨直肠肌,弯箭外侧括约肌,*内侧括约肌Coronal-T2WI白线示肛门最底部,黑箭肛提肌,组成坐骨直肠窝的顶部。Coronal-T2WI白箭直肠内层(黏膜及黏膜下层),黑箭肌层,刺箭直肠系膜MRI表现与病理的关系表现与病理的关系 MRI对直肠癌的确认和分期主要依赖于在T2WI上肿瘤、黏膜和黏膜下层、肌层、直肠周围脂肪和直肠系膜带的信号强度的不同。直肠系膜在T2WI为高信号,围绕低信号的固有肌层。肿瘤为中等信号,直肠筋膜表现为薄的线样低信号,包绕高信号的直肠系膜。直肠癌的TNM分期T分期Allen e
2、t al,AJR,2007 188Coronal-T2WI肿瘤突入肠腔,直肠肌层完整,白箭头直肠筋膜;病理:肌层完整(*),黑箭肿瘤腺体。直肠周围充满脂肪组织形成直肠系膜。78y/m with cecal cacinoma(false-positive)病理示,只有1个增大的淋巴结可见瘤细胞浸润。T2与T3期的鉴别的关键是直肠周围脂肪是否有侵犯表现为肌层与直肠周围脂肪的分界不清,可见圆形或结节样边界。Both high and low b value are low.肌层是受压变薄或受侵犯对累及到直肠筋膜(mesorectal fascia)的患者,结合术前放疗,2年内可以将局部复发从8.Co
3、ronal T2WIPre-and post-chemoradiotherapyCoronal-T2WIMRI示肿瘤侵犯直肠系膜脂肪和直肠系膜带(箭头),后者T3期中,肿瘤与直肠系膜带的最短距离非常重要。Both high and low b value are low.最近有学者认为以淋巴结的影像表现和信号来评估淋巴结转移的准确性更高,认为淋巴结边缘毛糙或模糊,信号花斑样不均匀为可疑转移性淋巴结。肌层(M)与脂肪(*)完整,且中间分界清晰(箭)229 103 mm2Both high and low b value are low.Axial T2WIcoronal T2WI很难鉴别T1还是
4、T2期肌层是受压变薄或受侵犯正常腺体(黑箭)与癌腺体(弯箭)有明确分界(*)肌层(M)与脂肪(*)完整,且中间分界清晰(箭)Coronal T2WIMRI示肿瘤侵犯黏膜、黏膜下层和肌层。病理示肌层(M)完全被肿瘤(箭)浸润T3期直肠筋膜受侵犯MRI示肿瘤侵犯直肠系膜脂肪和直肠系膜带(箭头),后者增厚,直肠筋膜代表手术范围,该类肿瘤术前辅助治疗可降低术后复发率。T4期肿瘤侵犯精囊可见直肠筋膜中断,并侵犯左侧精囊T2期MRI示肌层模糊不清,肿瘤似乎进入周围脂肪大体标本示肿瘤(*)似乎进入脂肪病理示肿瘤腺体(箭)侵犯肌层,但脂肪结构完整冠状位MRI可清晰显示病灶侵犯内括约肌(*)、外括约肌(ES)及
5、肛提肌(L).63y/m,rectal cancer,T3 stageTumor extends into surrounding mesorectal fat at 3-oclock,but no mesorectal fascia,CRM is 4mm63y/m with rectal caLymphatic node,mesorectal fascia is well.72y/m with rectal caPre-treatmentPost-treatment21y/f with rectal caPre-and post-chemoradiotheropyPre-treatmentP
6、re-treatment55y/m with rectal cancerPre-and post-chemoradiotherapy直肠癌MRI示在直肠周围间隙可见2个增大的淋巴结,病理示,只有1个增大的淋巴结可见瘤细胞浸润。Pre-and after contrast administatorRadiology 200867y/m with rectal ca-from 200472y/m recal ca-from 200465y/m with rectal cancerHigh b(up)and low b(down)value are high signalADC 1.229 103
7、mm2无论TME质量再好,1520的TME在CRM标本可见阳性癌细胞。内镜微创手术可安全有效地全层切除腺样息肉、原位癌和T1期的直肠肿瘤。78y/m with cecal cacinoma(false-positive)MRI可区分直肠壁的3层结构,T2WI在显示直肠壁结构时尤为重要。可见直肠筋膜中断,并侵犯左侧精囊Radiology 2008Pre-and after contrast administator无论TME质量再好,1520的TME在CRM标本可见阳性癌细胞。Coronal T2WI预测CRM是否被侵的标准是肿瘤与直肠系膜带之间的距离为6mm。白箭直肠内层(黏膜及黏膜但有时区分T1与T2期非常困难,是由于低的空间分辨率。78y/m with cecal cacinoma(false-positive)High and low b value are high signal,ADC 1.337 103 mm2/s,False-positive 1.374+/-0.157 78y/m with transverse colon caBoth high and low b value are low.True negative谢谢观看谢谢观看谢谢观看谢谢观看