高分辨T2WI结合T1WI增强扫描诊断直肠癌区域转移淋巴结的价值探讨

Value of high-resolution T2WI combined with enhanced T1WI in diagnosing regional lymph node metastasis of rectal cancer

目的比较高分辨二维快速自旋回波T2加权成像(简称平扫)及平扫结合各向同性高分辨三维梯度回波T1加权成像脂肪抑制增强扫描(简称增强扫描)诊断直肠癌不同短径范围的区域转移淋巴结的价值。方法纳入直接行全直肠系膜切除术且术前接受直肠高分辨MRI检查的直肠癌患者80例。两名放射科医师分别根据平扫及平扫结合增强扫描独立评价区域淋巴结性质。以短径5 mm和10 mm为界,将区域淋巴结分为三个亚组。以术后病理结果为金标准,计算平扫及平扫结合增强扫描诊断不同亚组区域转移淋巴结的敏感性、特异性及受试者工作特征曲线的曲线下面积(AUC)。结果影像与病理匹配的淋巴结共592枚。对于短径≤5 mm及短径>5 mm且≤10 mm的区域淋巴结,平扫结合增强扫描诊断区域转移淋巴结的敏感性均高于平扫(52.94%vs. 82.35%,P=0.002;65.28%vs. 97.22%,P<0.01),但特异性不如平扫(99.28%vs. 96.15%,P<0.01;98.36%vs. 67.21%,P<0.01)。两者诊断这两个亚组的价值均中等(AUC为0.761~0.893)。9枚短径> 10 mm的区域淋巴结均为恶性,平扫结合增强扫描均判定为转移,而平扫将其中1枚误判为良性。结论平扫结合增强扫描诊断直肠癌区域转移淋巴结的价值优于平扫,具有更高的敏感性。

Objective To compare the value of high-resolution two-dimensional turbo spin-echo T2-weighted imaging(plain scan for short)and plain scan combined with fat-suppressed gadolinium-enhanced isotropic high-resolution three-dimensional gradient recalled-echo T1-weighted imaging(plain scan combined with enhanced scan for short)in diagnosing regional lymph node metastasis with different short-axis diameter ranges in rectal cancer patients.Methods Eighty rectal cancer patients who underwent high-resolution MRI examination of rectum before total mesorectal resection were included.Two radiologists independently evaluated regional lymph node status based on plain scan and plain scan combined with enhanced scan.Regional lymph nodes were divided into three subgroups with short-axis diameter of 5 mm and 10 mm as boundaries.Using postoperative pathological results as the gold standard,the sensitivity,specificity and area under the receiver operating characteristic curve(AUC)for each subgroup were calculated.Results A total of 592 lymph nodes were include for the node-to-node evaluation.For the regional lymph nodes with short-axis diameter≤5 mm and short-axis diameter>5 mm and≤10 mm,the sensitivities of plain scan combined with enhanced scan were significantly higher than those of plain scan(52.94%vs.82.35%,P=0.002;65.28%vs.97.22%,P<0.01),but the specificities were not as good as plain scan(99.28%vs.96.15%,P<0.01;98.36%vs.67.21%,P<0.01).Both diagnostic values for these two subgroups were moderate(AUC:0.761-0.893).All nine regional lymph nodes with short-axis diameter>10 mm were malignant,which were judged to be metastatic by plain scan combined with enhanced scan,while one of them was misjudged to be benign by plain scan.Conclusion The value of plain scan combined with enhanced scan in diagnosing regional lymph node metastasis in rectal cancer is better than plain scan,with higher sensitivity.