探讨不同弥散加权成像（DWI）感兴趣区（ROI）的表观扩散系数（ADC）对评估直肠癌疗效的临床价值。

收集海南医学院第一附属医院收治经病理组织学确诊58例直肠癌患者资料，均采用新辅助放化疗（NCRT）治疗。分别在治疗前、后行磁共振（MRI）检查，DWI序列b=1000，以多个小样本法、最大层面法和整体容积法测量ADC值。比较各组不同测量方法ADC值差异，分析不同ROI法ADC值对直肠癌疗效的评估价值。

治疗前多个小样本法测得ADC值低于最大层面法和整体容积法，三种方法ADC值存在统计学差异（P<0.05）；治疗后多个小样本法测得ADC值高于最大层面法和整体容积法，三种方法ADC值存在统计学差异（P<0.05）。治疗后三种ROI法测量ADC值均明显高于治疗前（P<0.05）。病理完全缓解（pCR）组、未完全缓解（non-pCR）组及肿瘤退缩分级（TRG）缓解组、TRG未缓解患者三种ROI法测量ADC值均差异无统计学意义（P>0.05）。pCR组患者三种ROI法测量ADC值均明显高于non-pCR组，TRG缓解组患者三种ROI法测量ADC值均明显高于TRG未缓解（P均<0.05）。Spearman相关性分析显示，整体容积法对pCR标准和TRG标准的NCRT疗效负相关性最好（r=-0.557，-0.564，P<0.05）；多个小样本法和最大层面法对pCR标准和TRG标准的NCRT疗效均有负相关性（P<0.05）。pCR评价标准下，整体容积法、最大层面法、多个小样本法的AUC为0.816、0.781、0.721，敏感度为89.67%、85.82%、76.29%，特异度为82.60%、79.58%、84.33%。TRG评价标准下AUC为0.804、0.767、0.719，敏感度为87.12%、84.30%、74.24%，特异度为81.17%、76.53%、81.19%。

不同ROI勾画法测量ADC值均可评估直肠癌NCRT疗效，而整体容积法ADC值对评估直肠癌疗效的敏感度和特异度更具优势。

To investigate the clinical value of apparent diffusion coefficient (ADC) measurements in different diffusion weighted imaging (DWI) regions of interest (ROIs) in the evaluation of the therapeutic efficacy for rectal cancer.

A total of 58 patients diagnosed with rectal cancer by histopathological examination and underwent neoadjuvant chemoradiotherapy (NCRT) were included in the study. Routine MRI sequence and DWI sequence were performed before and after treatment, where the b-value of DWI sequence was 1000. The ADC values were measured by the multiple small samples method, maximum slice method, and overall volume method, respectively. According to the postoperative pathology, the patients were divided into either a complete response (pCR) group or a non-complete response (non-CR) group. The differences of ADC values among different groups with different measurement methods were compared, and ROC curve analysis was performed to analyze the value of different ADC measurements in evaluating NCRT efficacy for rectal cancer.

ADC values measured by the multiple small samples method before treatment were lower than those measured by the maximum layer method and global volume method, and there were statistical differences in ADC values between the three methods (P<0.05). After treatment, ADC values measured by multi-sample method were significantly higher than those measured by the maximum slice method and global volume method (P<0.05). ADC values measured by all the three ROI methods after treatment were significantly higher than those before treatment (P<0.05). ADC values measured by the three ROI methods did not differ significantly in the pCR group, non-pCR group, TRG remission group, and TRG non-remission group (P>0.05). ADC values measured by the three ROI methods were significantly higher in the pCR group than in the non-pCR group, and in the TRG remission group than in the TRG non-remission group (P<0.05 for all). Spearman correlation analysis showed that ADC values measured by the overall volume method had the best negative correlation with the therapeutic efficacy for NCRT assessed by both pCR and TRG criteria (r=-0.557 and-0.564, P<0.05). The ADC values measured by the multiple small samples method and maximum slice method were also negatively correlated with the therapeutic efficacy for NCRT assessed by both pCR and TRG criteria (P<0.05). According to the pCR evaluation criteria, the areas under the curves (AUCs) of the ADC values measured by the overall volume method, the maximum slice method, and the multiple small samples method were 0.816, 0.781, and 0.721, the sensitivities were 89.67%, 85.82%, and 76.29%, and the specificities were 82.60%, 79.58%, and 84.33%, respectively. According to the TRG evaluation criteria, the AUCs were 0.804, 0.767, and 0.719, the sensitivities were 87.12%, 84.30%, and 74.24%, and specificities were 81.17%, 76.53%, and 81.19%, respectively.

The ADC values measured by different ROI delineation methods can evaluate the efficacy of NCRT for rectal cancer, and the ADC values measured by the overall volume method were superior in terms of sensitivity and specificity.