容积CT对胃癌TN分期的诊断价值

Diagnostic value of volumetric CT in TN staging of gastric cancer

目的分析容积CT在胃癌初诊患者治疗前TN临床分期中的诊断价值。方法连续收集胃癌初诊患者共109例,所有患者术前接受容积CT对比剂增强扫描,并行根治性手术及病理学检查获得病理TN分期。由影像科医师观察胃癌在多平面CT图像上的影像表现判断临床T分期。用CT轴位图像测量区域淋巴结,分别以短径≥5、8及11 mm作为阈值判断转移并获得临床N分期,与术后病理分期对照,计算CT诊断胃癌治疗前TN分期的准确率。结果容积CT诊断胃癌T分期的准确率为86.2%,诊断早期胃癌及进展期胃癌T分期的准确率分别为80.0%和87.2%。以淋巴结短径≥5、8及11 mm作为阈值诊断转移时,判断患者存在淋巴结转移(即区分N0与N+)的准确率分别为79.8%、76.1%及62.4%,诊断N分期的准确率分别为51.4%、47.7%及43.1%。对于早期胃癌,以淋巴结短径≥5、8及11 mm作为阈值诊断N分期的准确率分别为73.3%、93.3%及100.0%;对于进展期胃癌,以淋巴结短径≥5、8及11 mm作为阈值诊断N分期的准确率分别为46.8%、40.4%及34.0%。结论容积CT诊断初诊胃癌治疗前T分期具有较高的准确率。治疗前使用CT诊断胃癌N分期能力不佳,区分N0与N+时以淋巴结短径≥5 mm作为阈值较好,对早期与进展期胃癌应采用不同的阈值判断N分期。

Objective To explore the diagnostic value of volumetric computed tomography （CT） in the pretreatment TN staging [American Joint Committee on Cancer （AJCC）, 7th edition] of gastric cancer. Methods A total of 109 consecutive patients with gastric cancer who underwent volumetric CT before treatment were included. They all received radical gastrectomy and lymph node dissection. The pTN staging was confirmed by histopathologic results. The radiologists performed the diagnosis of T staging with CT axial and multiplanar reconstruction images. They diagnosed metastatic lymph nodes with the short-diameter larger than or equal to 5 ram, 8 mm or 11 mm, respectively. Then they defined cN staging by the number of metastatic lymph nodes. Contrasted to the pathological TN staging, the accuracy of cTN staging by radiologist was calculated with statistical software. Results The accuracy of T staging with volumetric CT imaging for gastric cancer was 86.2%. The diagnostic accuracy of T staging for early and advanced gastric cancers was 80.0% and 87.2%, respectively. Using the short-diameter of node larger than or equal to 5 ram, 8 mm or 11 mm as diagnostic threshold, the accuracy was 79.8%, 76.1% and 62.4%, respectively. And the cN staging accuracy was 51.4%, 47.7% and 43.1%, respectively. For early gastric cancer, the cN staging accuracy was 73.3%, 93.3% and 100.0%, respectively. For advanced gastric cancer, the cN staging accuracy was 46.8%, 40.4% and 34.0%, respectively. Conclusion Volumetric CT had satisfying diagnostic value in the pretreatment TN staging of gastric cancer. But the cN staging accuracy was not satisfying. For distinguishing the patients with positive nodes or not, short-diameter of 5 mm as the threshold could perform better. It is suggested that different diagnostic thresholds for lymph node metastases in early and advanced gastric cancers should be used.