动态增强MRI在肺部结块病变中的诊断价值

Diagnostic value of dynamic contrast enhanced MRI in pulmonary nodules or masses

目的:探讨动态增强MRI在肺部结块样病变中的诊断价值。方法:66例经病理证实的肺结块样病变患者(恶性病变50例,良性病变16例)行常规MRI平扫及动态增强(DCE-MRI)检查,绘制时间-信号强度增强比曲线(TIC),并测量DCE-MRI参数:最大增强比(MER)、达峰时间(T_(max))、平均强化斜率(SLE)、最大强化斜率(SS)和廓清率。结果:本组病变的TIC分为4种类型:速升-下降型(A型)仅见于恶性肿瘤;速升-平台型和持续缓升型在良恶性结节中均可见,无明显强化型仅见于良性病变。肺鳞癌和小细胞癌的主要强化方式为环状强化,而腺癌为不均匀强化。DCE-MRI参数中,良性组Tmax明显较恶性组长(P<0.001),SLE明显小于恶性组(P=0.002)。T_(max)对良恶性病变的鉴别最具价值,临界值取280s时其诊断敏感度、特异度和符合率分别为88.0%、63.5%和76.5%。结论:DCE-MRI能提供肺结节血流动力学方面的信息,对肺部良恶性肿瘤的鉴别诊断具有较高价值。

Objective： The aim of this study was to investigate the value of dynamic contrast-enhanced MRI （DCE- MRI） in the diagnosis of pulmonary nodules or masses. Methods： A total of 66 patients with pulmonary nodules （50 cases with malignant nodules, 16 cases with benign lesions） proved by pathology underwent both conventional unenhanced and DCE-MRI scan. Time to contrast enhancement ratio curve （TIC） was obtained, and hemodynamic parameters including maximum CER （MER）, time at the peak enhancement ratio （Tmax）, mean slope of enhancement （SLE）, steepest slope （SS） and washout ratio were measured. Results：TICs in this study can be divided into four types：type A of rapid peak-descending pattern was only found in malignant lesions; type B of rapid peak-plateau pattern could be seen in benign and malignant nodules;type C of gradual increase pattern was mainly seen in benign group and few in malignant tumors;type D of flat pattern was only found in benign lesions. The main enhancement pattern of pulmonary small cell carcinoma and squamous carcinoma was ring-like enhanced. Heterogeneous enhancement was found in pulmonary adenocarcinoma. In the hemodynamic parameters,only Tmax of benign group was significantly longer, and SLE of benign group was significantly lower compared with malignant group with significant statistical difference （P〈0.00I;P=0. 002）. Taking Tmax = 2808 as cutoff value, the sensitivity, specificity and accuracy for detecting malignant lesions were 88.0 %, 63.5 % and 76.5 %, respectively. Conclusion： DCE- MRI can provide perfusion and hemodynamic information of pulmonary nodules,and is of great value in differential diagnosis of benign and malignant tumors of lung,in which Tmax is the most valuable parameter.