磁共振扩散成像与直肠癌术前放化疗病理反应性的对照研究

目的探讨磁共振扩散成像对直肠癌术前放化疗肿瘤消退分级的评价，以及与相关组织病理学变化的关系。方法对51例原发性直肠癌患者术前应用15T磁共振行MRI常规和扩散成像。测量放化疗前后肿瘤ADC值。比较ADG值及其变化与不同直肠癌消退分级的关系，及其与相关组织病理学变化的相关性。结果降期组、末降期组、RCRGI—3级间治疗前肿瘤平均ADC值差异有统计学意义（F=3.754，p=0.007）；RCRG1级与RCRG3级、T-未降期；RCRG2级与RCRG级；RCRG3级与T-降期；T-降期与T-未降期间差异有统计学意义（P〈005）。不同RCRG分级间炎性反应程度、细胞核异型性程度和肿瘤细胞死亡程度均不相同，差异有统计学意义。RaRG1级与2级间的细胞核异型性、肿瘤细胞死亡程度差异有统计学意义（P〈0.05），ReRG1级与3级间的炎性反应程度、细胞核异型性、肿瘤细胞死亡程度差异均有统计学意义（P〈0．05）；RCRG2级与3级间细胞核异型性差异有统计学意义（P〈0.05）。结论磁共振扩散加权成像可以反映直肠癌病理消退分级间的差异；肿瘤降期与肿瘤消退分级间有较好的对应关系；RCRG1级与2级ADC值变化趋势相同，但幅度不同，与治疗反应性程度相关。放化疗反应性好的直肠癌病例在治疗第一周出现ADC值明显升高，但肿瘤体积下降不明显，可能与这部分病例经常伴有明显的炎性反应有关。放化疗反应性好病例的肿瘤细胞核异型性明显，与其肿瘤细胞更易受辐射和化疗药物损伤有关。

A Comparative Study in Rectal Carcinoma between Diffusion Weighted MR Imaging and Histopathologic Response with Preoperative Chemoradiotherapy

Objective To evaluate the predictive and early monitoring value of DWMRI on rectal cancer regression grade （RCRG） of concurrent radiotherapy in patients with primary rectal carcinoma, and to investigate the correlation between tumor ADC values and histopathologic changes. Methods Fiftyone patients with primary rectal carcinoma undergoing preoperative chemoradiation were recruited in the study. Diffusion weight imaging （DWI） was performed pretreatment and preoperation of all patients. GE 1.5T MR scanner with an 8-channel body phase-array coil was used. The mean ADC values of the tumor region was calculated and compared with the postsurgical histopathologic RCRG. Results The mean ADC value in RCRG1 group with good response （1.11±0.12） and RCRG2 group with moderate response （1.18±0.15） were lower than that in RCRG3 group with poor response （1.31 ±0.18） before onset of chemoradiation （F=5.353, RCRG1 vs. RCRG3, p=0.002; RCRG2 vs. RCRG3, p=0.019; RCRG1 vs. RCRG2, p〉0.05）. Tumor Necrosis, inflammation, cytonuclear Atypia were significantly different among all RCRG groups（p〈0.05）. Gonclusion ADC value can reflect the different among RCRG groups. Good response group has obvious atypia, and that indicated tumor cells more vulnerable to radiation and chemotherapy, easily leaded to apoptosis and necrosis.