MR扩散加权成像在颈部淋巴结结核诊断中的价值

目的 探讨MR扩散加权成像(diffusion weighted imaging,DWI)在颈部淋巴结结核诊断中的价值。方法 收集武汉市肺科医院2016年5月至2018年5月临床确诊为颈部淋巴结结核的132例患者作为研究对象,其中,男33例(25.0%),女99例(75.0%);年龄范围15~73岁,年龄中位数(四分位数)[M(Q₁,Q₃)]为27(22,48)岁;病程为14d至6年,病程M(Q₁,Q₃)为60(30,180)d。收集研究对象临床信息,以及颈部淋巴结结核的淋巴结大小、数量、分布特点、MR成像信号特点及表观扩散系数(ADC)值,分析其影像学特征性表现。结果 132例淋巴结结核患者中,DWI共发现异常淋巴结2032枚,其中右侧1127枚,左侧905枚,淋巴结平均直径为(21.32±6.50)mm。按照影像学分区,共累及503例次,主要分布在第Ⅱ区[161例次(32.01%)]、第Ⅳ区[113例次(22.47%)]。按照影像学形态结合病理分为4期,共累及292例次,Ⅰ期有100例次(34.25%),Ⅱ期有71例次(24.32%),Ⅲ期有71例次(24.32%),Ⅳ期有50例次(17.12%)。Ⅰ期在T₁WI为稍低信号,T₂WI、DWI为高信号,DWI部分淋巴结呈裂隙状低信号;Ⅱ、Ⅲ、Ⅳ期淋巴结坏死区在T₁WI呈低信号,T₂WI、DWI呈高信号。部分颈淋巴结结核痊愈后,纤维硬结灶及钙化灶表现为“四低”现象,即T₁WI、T₂WI、DWI、ADC图均呈低信号。脓肿区T₁WI、T₂WI均呈稍低信号,DWI呈明显高信号,实质部分与坏死区间DWI呈环形低信号。行DWI扫描时,在扩散敏感系数(b值)分别为0、200、500、1000、2000s/mm ²时,相应ADC值[M(Q₁,Q₃)]分别是0.935(0.787,1.504)×10 ^-3mm ²/s、1.254(0.970,1.565)×10 ^-3mm ²/s、1.039(0.769,1.290)×10 ^-3mm ²/s、0.842(0.625,1.193)×10 ^-3mm ²/s、0.687(0.337,0.859)×10 ^-3mm ²/s,5组ADC值比较,差异有统计学意义(H=34.16,P<0.01)。结论 MR常规序列结合DWI及ADC值对颈部淋巴结结核诊断及鉴别诊断有重要价值。

The diagnostic value of MR diffusion-weighted imaging in cervical lymph node tuberculosis

Objective To evaluate the value of MR diffusion-weighted imaging (DWI) in the diagnosis of cervical lymph node tuberculosis. Methods From May 2016 to May 2018, a total of 132 patients with cervical lymph node tuberculosis diagnosed clinically in Wuhan Pulmonary Hospital were collected as the study object, including 33 males (25.0%) and 99 females (75.0%), with the age of 15 to 73 years old and the median age (M(Q₁,Q₃)) of 27 (22, 48) years. The course of disease was 14 days to 6 years, and the median (M(Q₁,Q₃)) was 60 (30, 180) days. The clinical information of the subjects, the size, quantity, distribution characteristics of lymph nodes, as well as MR imaging signal characteristics and apparent diffusion coefficient (ADC) value of cervical lymph node tuberculosis were collected, and the imaging characteristics were analyzed. Results DWI showed that among the 132 patients with cervical lymph node tuberculosis, there were 2032 abnormal lymph nodes, including 1127 on the right and 905 on the left, and the average diameter of lymph nodes was (21.32±6.50) mm. According to the imaging subarea, a total of 503 subarea were involved, which mainly distributed in Ⅱ areas (161 cases, 32.01%) and Ⅳ areas (113 cases, 22.47%). In accordance with the imaging morphology and pathology, four stages were divided and the total frequency of stage was 292 cases, including 100 cases (34.25%) in stage Ⅰ, 71 cases (24.32%) in stage Ⅱ, 71 cases (24.32%) in stage Ⅲ (24.32%), and 50 cases (17.12%) in stage Ⅳ. In stage Ⅰ of cervical lymph node tuberculosis, the signal intensity was slightly hypo-intensity in T₁WI sequence, high signal intensity in T₂WI and DWI sequence, and slit-shaped Hypo-intensity in some lymph nodes of DWI sequence; meanwhile, the low signal intensity in T₁WI sequence, as well as high signal intensity in T₂WI and DWI sequence were found in necrotic area of lymph nodes at stage Ⅱ, Ⅲ and Ⅳ. After the recovery of some cervical lymph node tuberculosis, the fibrosis nodules and calcification showed “four low” phenomena, that was, T₁WI, T₂WI, DWI, and ADC images all showed low signal intensity. The abscess area showed slightly hypo-intensity signal in T₁WI and T₂WI sequence, and significantly hyper-intensity in DWI, while annular hypo-intensity could be seen between parenchyma and necrotic region. Based on DWI scanning, when the diffusion sensitivity coefficients (b values) were 0, 200, 500, 1000, 2000 s/mm ², the corresponding ADC values (M(Q₁,Q₃)) were 0.935 (0.787, 1.504)×10 ^-3 mm ²/s, 1.254 (0.970, 1.565)×10 ^-3 mm ²/s, 1.039 (0.769, 1.290)×10 ^-3 mm ²/s, 0.842 (0.625, 1.193)×10 ^-3 mm ²/s, and 0.687 (0.337, 0.859)×10 ^-3 mm ²/s, respectively. There was significant difference in ADC values between 5 groups (H=34.16, P<0.01). Conclusion MR routine sequence combined with DWI and ADC value exhibits great value in the diagnosis and differential diagnosis of cervical lymph node tuberculosis.