多b 值弥散加权成像在脑转移瘤诊断中的应用价值

Value of MR multiple b-value diffusion-weighted imaging in diagnosis of metastatic tumors of brain

摘要:

目的 探讨MR 多b 值弥散加权成像（DWI）在脑转移瘤诊断中的应用价值。方法 回顾分析2014 年6 月-2016 年6 月经临床和影像学证实的16 例脑转移瘤患者，均行核磁共振（MR）常规序列、多b值DWI 序列及增强扫描检查。统计分析多b 值DWI 序列及增强扫描对于脑转移瘤的检出差异，同时观察不同b 值DWI 下病灶实质部分ADC 值的变化趋势。结果 MR 增强扫描提示病灶单发5 例，多发11 例，累计病灶数目130 枚，其中直径≥ 5 mm 病灶53 枚，<5 mm 病灶77 枚。多b 值DWI 序列提示病灶数目99 枚，其中直径≥ 5 mm 瘤灶50 枚，<5 mm 病灶49 枚。以增强扫描作为检出数目金标准，多b 值DWI 序列对直径≥ 5 mm 病灶检出率为94.3%，具有较好一致性。而瘤灶<5 mm 时，多b 值DWI 序列检出率为63%，敏感性下降。同时高b 值DWI 所测病灶实质部分ADC 值均小于较低b 值DWI，随着b 值的升高，病灶ADC 值呈下降趋势。结论 多b 值DWI 对于直径≥ 5 mm 脑转移瘤的检出与增强扫描具有良好的相关性，在脑转移瘤的临床筛查方面具有重要意义，但对于<5 mm 的微小病灶检出率低于MR 增强扫描。

Abstract:

Objective To evaluate the value of MR multiple b-value diffusion-weighted imaging (DWI) in the diagnosis of metastatic tumors of brain. Methods A retrospective study was carried out on 16 cases of patients with brain metastases confirmed by clinical and imaging findings from June 2014 to June 2016. All of the patients underwent MR routine sequence, multiple b-value DWI sequence and enhanced scan. The differences between multiple b-value DWI sequence and enhanced scan for the detection of brain metastases were statistically analyzed,and the changes of the ADC value of the multiple b-value DWI sequence were observed. Results Enhanced MR scan revealed single lesion in 5 cases and multiple lesions in 11 cases with a total of 130 lesions, including 53 lesions with the diameter ≥ 5 mm and 77 lesions <5 mm. Multi-b DWI sequence indicated the number of lesions was 99, including 50 foci with the diameter ≥ 5 mm and 49 foci <5 mm. Using enhanced scan as the gold detection standard of the detected number, the detection rate of the lesions ≥ 5 mm by multiple b-value of DWI sequence was 94.3%, with good consistency; when the tumor was <5 mm, the detection rate of multi-b value DWI sequence was 63.0%, the sensitivity was decreased. At the same time, the ADC value of the lesion parenchyma measured by high b-value DWI was lower than that by low b-value DWI, and the ADC value of the foci decreased with the increase of b value. Conclusions Multi b-value DWI has a good correlation with enhanced scan for the detection of brain metastatic tumors with diameter of 5 mm and over, and has important significance in clinical screening of brain metastases; but for the lesions under 5 mm, the detection rate is lower than that of MR enhanced scan.