CT衰减值在术前评估低位直肠癌直肠周围间隙侵犯和小淋巴结转移的应用价值

Application Value of CT Attenuation Value in Preoperative Evaluation of Rectal Cancer Invasion and Lymph Node Metastasis in Low Rectal Cancer

目的初步探讨低位直肠癌直肠周围脂肪间隙的平均CT值对于判断低位直肠癌周围脂肪间隙侵犯和直肠周围小淋巴结转移的应用价值。方法前瞻性纳入2011年7月至2013年2月于本院拟行外科手术治疗并被术前病理结果证实为低位直肠癌患者。所有患者均于术前接受Philips Brilliance 64排螺旋CT全腹检查,并于后处理工作站对图像进行观察测量。采用ROI CT值测量法分别测出每个病例在平扫及增强时直肠周围脂肪间隙的平均CT值。结合病理结果,根据有无直肠周围脂肪间隙侵犯将病例分为T(+)、T(-)两组,根据有无直肠周围小淋巴结转移将病例分为N(+)、N(-)两组,分别比较T(+)、T(-)两组患者及N(+)、N(-)两组患者的ROI平均CT值的差异性。结果 T(-)组与T(+)组患者直肠周围脂肪间隙ROI CT值差异有统计学意义(P<0.05),N(-)组与N(+)组患者直肠周围脂肪间隙ROI CT值差异有统计学意义(P<0.05)。其ROC诊断效能曲线下面积有统计学意义(平扫:AZ=0.686,P=0.016;增强:AZ=0.682,P=0.019)。平扫及增强时,当ROI平均CT值取-80^-70 Hu为诊断直肠周围间隙侵犯参考值;平扫及增强时,当ROI平均CT值取-70^-60Hu,为诊断直肠周围小淋巴结转移的参考值。结论直肠周围脂肪间隙CT表现分型及ROI平均CT值的测量能够为直肠癌周围脂肪间隙侵犯和直肠周围小淋巴结转移提供辅助诊断依据。

Objective To evaluate the clinical value of ROI mean CT attenuation value in judgement of pararectal space invasion and small lymph nodes metastases on lower rectal cancer. Methods Prospectively enrolled 69 cases diagnosed as lower rectal cancer from July 2011 to Feb 2013. All the cases were assessed by MSCT before operation,,and the images were observed and measured in post processing work station. ROI CT value measurement method was used respectively to measure average CT value of each case in the scan and enhanced of fat gap around the rectum. Combined with the pathological results,according to the presence or absent of fat gap around the rectum infringement were can be divided into T（ ＋）,T（-） two groups,according to the presence or absent of rectum around small lymph node metastasis were divided into two groups N（ ＋）,N（-）. then,between two groups of patients,T（ ＋）,T（-） compared the ROI of the average CT value with N（ ＋）,N（-）. Results The differences of ROI mean CT value of pararectal space between T（ ＋） and T（-）,N（ ＋） and N（-） patients were statistically significant（ P〈 0. 05）;furthermore,the accuracy of diagnosing pararectal space invasion and small lymph nodes metastases by ROI mean CT attenuation value were statistically significant（ P 〈0. 05）. The best cut-off ROI mean CT attenuation value for pararectal space invasion and small lymph nodes metastases were-80 Hu-70 Hu and-70 Hu-60 Hu,respectively. Conclusion Fat gap garound the rectum and type of CT performance and the average ROI CT value could be supply diagnostic evidence for pararectal space invasion and small lymph nodes metastases.