相对表观弥散系数与钆喷替酸葡甲胺增强MRI诊断兔头颈转移淋巴结的对比研究

目的:比较相对表观弥散系数(rADC)和钆喷替酸葡甲胺(Gd-DTPA)增强MRI诊断兔头颈部转移淋巴结的准确性。方法:24只新西兰大白兔,随机分成2组,每组12只,分别建立炎性淋巴结模型、VX2肿瘤淋巴结转移模型。Gd-DTPA增强前行T1WI、T2WI、磁共振弥散加权成像(DWI)序列扫描,注射Gd-DTPA 80s后行T1WI序列扫描。测量淋巴结、同层肌肉的ADC值,计算淋巴结/肌肉的rADC值,测量增强前、后T1WI序列淋巴结、同层肌肉的信号强度(SI)值,计算增强前后信号强度比值(SIr),并进行统计学分析。结果:经病理证实,炎症组取出淋巴结26枚,肿瘤组取出转移淋巴结14枚。炎症组、肿瘤转移组淋巴结的rADC值、SIr值差异均具有统计学意义(t值分别为-8.30,4.76,P均<0.05);利用rADC值鉴别良、恶性淋巴结ROC曲线下面积(AUC)是0.93,阈值0.88,灵敏度为92.3%,特异度为92.9%;SIr值的AUC是0.81,阈值是1.66,灵敏度为78.6%,特异度为88.5%。结论:炎症组、肿瘤转移组淋巴结的rADC值、SIr值差异具有统计学意义;rADC值比钆剂增强扫描SIr值鉴别转移性淋巴结具有较高的准确性。

Comparison between relative apparent diffusion coefficient and Gd-DTPA-enhanced MRI in diagnosing metastatic lymph nodes of head and neck in rabbit models

Objective： To compare the diagnostic accuracy of the relative apparent diffusion coefficient（rADC）with gadolinium-enhanced MR in differentiating the metastatic lymph nodes in head and neck rabbit models.Methods： 24 New Zealand white rabbits were randomly divided into two groups with 12 rabbits in each group.The inflammatory and metastatic lymph nodes group was established respectively.T1-weighted image（T1WI）,T2-weighted image（T2WI）,and diffusion weighted imaging（DWI）sequence scan were performed on each model,and after 80 seconds administration of Gd-DTPA,T1WI were acquired.ADC values of lymph nodes and the same level of muscle were measured,then lymph node / muscle rADC value were calculated.Standardized signal intensities（SI）values of lymph nodes and SI values of the same level of muscle were measured before and after Gd-DTPA enhanced T1WI sequences,SIpost/SIpre were calculate and analyzed statistically.Results： Confirmed by pathology,the number of the lymph nodes of inflammation group,metastasis lymph node group was 26,14 respectively.Independent-samples t-test was conducted to compare the differences of benign and malignant lymph nodes.rADC value,SIr value,both were statistically significant（all P〈0.05）.A receiver operating characteristic analysis was conducted to compare the diagnostic value of rADC value and SIr value,when using rADC value area under the ROC curve（AUC）was 0.93,and the threshold value of rADC was 0.88,while the sensitivity,specificity was 92.3%,92.9% respectively;when using SIr value the AUC area was 0.81,the threshold was 1.66,the sensitivity,specificity was78.6%,88.5%respectively.Conclusion： There is a difference of rADC value and SIr value of lymph nodes between inflammation and neoplasms metastasis groups.rADC value can be more accurate than SIr value in differentiating benign and malignant lymph nodes in rabbit models.