低位直肠癌磁共振影像学分期的精确评估  

Precise assessment of low rectal cancer by magnetic resonance imaging

作　　者：王屹[1] 

机构地区：[1]北京大学人民医院放射科,北京100029

出　　处：《中国实用外科杂志》2017年第6期605-609,共5页Chinese Journal of Practical Surgery

摘　　要：局部进展期低位直肠癌的主要治疗策略仍为根治性手术。由于解剖结构特殊,低位直肠癌经根治性手术后病理学环周切缘(pathological circumferential resection margin,pCRM)阳性率明显高于中上段直肠癌。术前准确分析直肠癌与直肠肛管肌层、括约肌复合体、肛提肌以及周围器官的相互关系,有助于合理选择手术切面并降低pCRM阳性率。高分辨率磁共振影像(MRI)则已经被应用于判断与pCRM相关的危险因素,包括直肠癌侵犯至内括约肌全层及以上,直肠癌与直肠系膜筋膜或肛提肌间距离<1mm,直肠癌下缘与肛缘距离<4 cm,直肠癌位于前1/4象限,以及直肠壁外血管侵犯等。如果存在上述危险因素建议行扩大的腹会阴联合切除术以避免pCRM阳性的发生。低位直肠癌经根治性手术治疗即意味着器官丢失,对于保肛意愿强烈的病人导致生活质量下降。目前,新辅助放化疗局部控制能力显著提高,直肠癌原发灶明显退缩,甚至可以达到病理学完全缓解。特别是对于低位直肠癌,经新辅助放化疗并获得临床完全缓解(cCR),则存在实施非手术治疗的可能。在判断临床完全缓解时,影像学检查特别是MRI发挥着重要的作用。应用MRI判断肿瘤体积变化值,肿瘤再分期,MRI肿瘤退缩分级等被应用于判断cCR。未来的研究将结合形态学及功能学共同应用于直肠癌新辅助放化疗效果的评价中。The primary strategy for low rectal cancers is curative operation. In results of anatomic characteristics,low rectal cancers treated with abdominoperineal excision （APE） have a higher rate of margin involvement compared with tumours elsewhere in the rectum. It is necessary to analyze the relationship between low rectal cancer and surrounding structures and organs before operation. High-resolution magnetic resonance imaging （MRI） can be used to assess risk factors related with margin involvement,including tumor extended to full thickness of the muscularis propria/internal sphincter,extends into the intersphincteric plane, or extends into the external sphincter or 〈1 mm from levator ani, anterior quarter invasion, extramural vascular invasion, and less than 4cm from anal verge. Risk factors can be used to correct surgical management to minimize the rate of margin involvement. Local control rate of rectal cancer has been improved after neoadjuvant chemoradiation and even pathological completed response （pCR） has been demonstrated in a significant minority. If the patients with clinical completed response to neoadjuvant chemoradiation can be demonstrated by clinical and medical imaging findings, a nonoperative management （NOM） strategy has been pursued to preserve sphincter function and avoid complications induced by surgery. MRI could be used to assess completed response of rectal cancer to neoadjuvant chemoradiotherapy. The Future research must focus on the integration of morphological and functional imaging with clinical data and molecular biomarkers.

关 键 词：磁共振影像 低位直肠癌 

分 类 号：R6[医药卫生—外科学]