-对直肠癌新辅助治疗后分期的准确性

根据文献报道，普通MRI（T1WI，T2WI，普通增强）判断直肠癌放疗、化疗后T分期准确性较低，为43%～52%，N分期准确性60%～78%，究其原因是放疗后组织水肿、纤维化等影响了分期准确性。而动态增强则可以有效地区分肿瘤和周围炎症组织及纤维化，因肿瘤多呈早中期明显强化，而周围炎症组织、纤维化均为晚期明显强化的特征，使得放疗、化疗后T/N再分期的准确性提高，充分显示出DCE-MRI用于放疗、化疗后术前再分期的优势。

图6-9-1 CRT治疗前后T1WI增强扫描矢状位图像

注：治疗前肠壁增厚形成肿块，动脉期肿块明显强化（A），治疗后肿块明显缩小（B）。正常肠壁延迟期强化

图6-9-2 CRT治疗前后动态增强及曲线1

注：男，54岁。便中带血3个月。入院肠镜活检：高分化腺癌，部分呈黏液腺癌。行术前新辅助放疗、化疗。治疗前MRI显示肿块于注药早期明显强化，曲线速率高于正常肠管（1.43vs0.73）（A，B）；治疗后MRI肿块明显变小，原肿块部分强化曲线同下段正常肠管（0.7vs0.71）（C，D）；行腹腔镜MILES手术，术后病理：标本可见大量黏液，黏液池内少量漂浮的坏死的癌细胞，符合腺癌化疗后改变

图6-9-3 CRT治疗前后动态增强及曲线2

注：女，61岁，便中带血3个月。入院肠镜：直肠腺癌，中分化。治疗前MRI:肿块于动脉期明显强化；曲线上升速率高于下段肠管（1.74vs0.60）（A，B）。治疗后MRI原肿块部位未见明显强化，曲线同下段肠管（0.95vs0.94）（C，D）。行TME手术，术后病理：直肠溃疡，肠壁黏膜及肌层未见癌细胞残留，有明显纤维化及淋巴细胞、浆细胞、嗜酸细胞浸润。符合化疗后改变

图6-9-4 治疗后未达完全缓解病例的动态增强图像及曲线

注：直肠癌CRT治疗后，DCE-MRI仍可见异常强化的肿块，肿块曲线上升速率高于下段肠管（1.06vs0.26）。行TME手术，术后病理：隆起型腺癌，中分化，侵犯全层达外周脂肪

（李春媚 陈 敏 欧阳汉 全冠民 刘佩芳）

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