磁共振高b值DWIBS对脑转移瘤筛查的价值

The Value of MR High- b- value DWIBS in Detecting the Brain Metastases

目的探讨磁共振高b值背景抑制扩散加权成像(DWIBS)对脑转移瘤筛查的价值。方法选取经临床或病理证实的脑转移瘤32例,均行颅脑MRI平扫及增强扫描,DWIBS序列使用普通b值(b=0,1000 s/mm2)和高b值(b=0,3000 s/mm2)两种。回避坏死囊变区,测量肿瘤实质区和邻近正常脑白质的信号强度(SI)、背景噪声的标准差及表观扩散系数(ADC)值,计算两种不同b值DWIBS序列中病灶的信噪比(SNR)、对比噪声比(CNR)及对比度(CR)。结果高b值DWIBS对病灶诊断的正确率优于普通b值。脑转移瘤在高b值DWIBS序列的CNR、CR及SI病变/SI正常明显高于普通b值(Q=3.712,P<0.05;Q=5.149,P<0.01;Q=5.143,P<0.01),其SNR明显低于普通b值(Q=4.500,P<0.05);增强T1WI的SNR显著高于高b值(Q=6.407,P<0.01)。高b值DWIBS上ADC值明显低于普通b值(t=8.312,P=0.000)。结论高b值DWIBS对脑转移瘤的筛查有较大价值,尤其对于肾功能不良的患者,是免除对比剂应用又简便易行的方法。

Objective To explore the value of MR high - b - value diffusion weighted imaging with background sup pression （DWIBS） in detecting the brain metastases. Methods 32 patients with brain metastases confirmed by clinically and pathologically were collected. All the patients underwent conventional MR1 and contrast enhanced MRI, and DWIBS using two types b value： ordinary b value （b = 0, 1000s/mm2）and high -b -value （b = 0, 3000 s/ram2）. Cystic necrosis area was avoid, the signal intensity （SI）, background noise and apparent diffusion coefficient （ADC） value of tumor pa- renchyma and adjacent normal white matter were measured. The averages of signal to noise ratio （SNR）, contrast to noise ratio （CNR） and contrast ratio （CR） were calculated. Results The lesion diagnostic accuracy rate of high - b - value DWIBS was better than that of ordinary b value. On high - b - value DWIBS sequence, the CNR, CR and Sllesion/Slnormal of brain metastasis was significant higher than that of ordinary b value DWIBS sequence （ Q = 3. 712 ,P 〈 0. 05 ; Q = 5. 149 ,P 〈0. Ol ;Q =5. 143 ,P 〈0. Ol ）. and the SNR was significant lower than that of ordinary b value DWIBS sequence （ Q = 4. 500,P 〈 0.05）. The CNR of contrast - enhanced T~ WI was significant higher than that of normal brain tissue （ Q =6. 407,P 〈0.01 ）. The ADC value in High- b- value DWIBS sequence was significant lower than that in ordinary b value DWIBS sequence （t = 8. 312 ,P = 0. 000）. Conclusion High -b -value DWIBS sequence has a great value in de tecting brain metastases, especially for patients with poor kidney function, it is a simple method and can be used to avoid potential injury of contrast agent.