依据CT及MRI确定区域淋巴结转移的病理对照研究

目的 评估分别依据CT及DWMRI确定胸部肿瘤区域淋巴结转移的诊断效能,寻找更为合理准确的淋巴结勾画方法及界值。方法 2012—2013年共入组43例胸部肿瘤患者(食管癌35例、NSCLC 8例),术前1周完善胸腹强化CT及DWMRI检查,分别依据CT及DWIMR图像确定转移的区域淋巴结,以术后病理为金标准统计并比较两种方法的诊断效能。两种图像结果行χ²检验。结果 CT图像与DWI诊断区域淋巴结转移的敏感性、特异性、准确性、阳性预测值、阴性预测值、约登指数分别为57.1%、96.3%、93.8%、50.0%、97.2%、53.4%和60.0%、98.9%、96.5%、77.8%、97.4%、58.9%,DWMRI诊断的特异性、准确性、阳性预测值优于CT (P=0.005、0.038、0.022)。依据CT诊断的40个淋巴结中20个为假阳性,其中15个(75%)可经DWMRI信息纠正。CT诊断假阴性淋巴结15个,其中3个(20%)可经DWMRI得以分辩。全组35个癌性淋巴结中5个影像学未见明确肿大,余30个中有13个短径<1.0 cm (43.3%)。结论 依据CT判断区域淋巴结转移局限性明显,单以短径≥1.0 cm作为靶区勾画标准可能会漏照较多癌性淋巴结。DWMRI诊断区域淋巴结转移的特异性、准确性及阳性预测值优于CT,可有效排除非癌性肿大淋巴结并分辨部分小的转移性淋巴结。

A comparative study of computed tomography and magnetic resonance imaging in pathological diagnosis of regional lymph node metastasis

Objective To evaluate the efficacy of computed tomography (CT) and diffusion-weighted magnetic resonance imaging (DWMRI) in the diagnosis of regional lymph node metastasis in thoracic carcinoma, and to figure out the methods and thresholds for delineation of lymph nodes with higher reasonability and accuracy. Methods A total of 43 patients with thoracic carcinoma, including 35 patients with esophageal cancer and 8 patients with non-small cell lung cancer, were enrolled as subjects from 2012 to 2013. All patients received abdominal CT scan and DWMRI examination one week before surgery, and regional lymph node metastasis was diagnosed based on the images of CT scan or DWMRI. With the postoperative pathology as the gold standard, the diagnostic efficacy was evaluated and compared between the two methods. The two sets of obtained images were analyzed using the χ²-test. Results The sensitivity, specificity, accuracy, positive predictive value, negative predictive value, and Youden’s index of CT versus DWMRI in the diagnosis of regional lymph node metastasis were 57.1% vs. 60.0%, 96.3% vs. 98.9%, 93.8% vs. 96.5%, 50.0% vs. 77.8%, 97.2% vs. 97.4%, and 53.4% vs. 58.9%, respectively;the specificity, accuracy, and positive predictive value of DWMRI were significantly superior to those of CT (P=0.005,0.038,0.022). Twenty out of forty lymph nodes diagnosed by CT scan were false positive, and 15(75%) of them could be corrected by DWMRI. Fifteen out of forty lymph nodes diagnosed by CT scan were false negative, and 3(20%) of them could be recognized by DWMRI. In all 35 metastatic lymph nodes, 5 lymph nodes had no apparent swelling on images, and 13(43.3%) out of the other 30 lymph nodes had a short diameter less than 1.0 cm. Conclusions CT scan has apparent limitation in the diagnosis of regional lymph node metastasis. Many metastatic lymph nodes would be missed if a short diameter not lessthan 1.0 cm is the only standard for target volume delineation. With superior specificity, accuracy, and positive predictive value to CT in the diagnosis of regional lymph node metastasis, DWMRI can effectively rule out non-cancerous intumescent lymph nodes and recognize some of small metastatic lymph nodes.