MRI扩散加权成像评价孤立性肺结节的价值

Evaluation of solitary pulmonary nodule by diffusion-weighted MR imaging

目的：探讨MRI扩散加权成像（diffusion weighted imaging,DWI）对良、恶性孤立性肺结节（solitary pulmonary nodule,SPN）鉴别诊断价值,以及优化最佳b值选择。方法收集2012年1月至2014年5月CT检查发现SPN患者82例,并经手术、针刺活检、综合影像或临床治疗随访后证实,其中恶性患者45例,良性患者37例,全部行MRI胸部常规T1WI、T2WI和DWI检查,b值选择300,500,800和1000s/mm2。以SPN在T1WI最大直径15mm为标准分为两组,分别测量在不同b值情况下的ADC值。结果良、恶性SPN的ADC值均随b值增加而逐渐变小,最大直径小于15mm组中,良、恶性SPN在b值=500s/mm2时,其ADC值差异有统计学意义（t=2.35,P〈0.05）；最大直径大于15mm组中,良、恶性SPN在b值为800-1000s/mm2时,其ADC值差异有统计学意义（t=2.30,P〈0.05；t=4.08,P〈0.01）。结论SPN大小是DWI的b值选择影响因素,DWI鉴别诊断SPN具有重要临床应用价值。

Objective To evaluate the values of diffusion weighted imaging（DWI）in the differential diagnosis of benign and malignant solitary pulmonary nodule（SPN）by magnetic resonance imaging（MRI）and to optimize the b values for MRI.Methods Eighty-two SPN patients diagnosed by CT examination from January 2012 to May 2014 were enrolled in this study.All patients were confirmed by surgery,needle biopsy,combined imaging and clinical follow-up,among which there were 45 cases of malignant SPN and 37 cases of benign lesions.All patients underwent T1 weighted imaging（T1 WI）,T2 weighted imaging （T2 WI）and DWI examination with b values of 300,500,800 and 1 000 s/mm2 .The lesions were divided into two groups by a cut-off diameter of 1 5 mm under T1 WI,and then the apparent diffusion coefficient（ADC）values of the lesions under DWI with different b values were measured.Results The ADC values of benign and malignant SPNs were gradually reduced with the increase of b values.Among the lesions with maximum diameter less than 1 5 mm,the ADC values of benign and malignant SPNs showed statistically significant difference at b value of 500 s/mm2 （t = 2.35,P 〈 0.05 ）.However,among the lesions with maximum diameter larger than 1 5 mm,the ADC values of benign and malignant SPNs were significantly different at b value of 800 to 1 000 s/mm2 （t =2.30,P 〈0.05 and t =4.08,P 〈0.01 ）.Conclusion The size of SPNs is an influencing factor for the choice of b values and DWI has important clinical application value in the differential diagnosis of SPNs.