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。Axial T2WIcoronal T2WI很难鉴别T1还是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
3、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 r
4、ectal caPre-treatmentPost-treatment21y/f with rectal caPre-and post-chemoradiotheropyPre-treatmentPre-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 rec
5、al ca-from 200465y/m with rectal cancerHigh b(up)and low b(down)value are high signalADC 1.229 103 mm2/s(malignant 1.194+/-0.15278y/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
