A comparative study of computed tomography and magnetic resonance imaging in pathological diagnosis of regional lymph node metastasis / 中华放射肿瘤学杂志

ABSTRACT

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 less than 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.