FLAIR增强扫描在脑转移瘤诊断中的价值

The Diagnostic Value of Enhanced Fluid Attenuated Inversion Recovery MR Imaging in Brain Metastases

目的通过与平扫液体衰减反转恢复(FLAIR)及增强T1WI的比较研究,探讨增强FLAIR序列在脑转移瘤诊断中的价值。资料与方法20例脑转移瘤患者行增强前后T1WI和FLAIR成像,计数两种序列上转移瘤的数目,测量肿瘤强化程度、强化百分比和肿瘤体积,计算肿瘤与白质、肿瘤与脑脊液的对比率(CR)和对比噪声比(CNR)。结果20例中1例仅增强T1WI发现3个点状强化灶,余19例共327个转移灶中平扫FLAIR序列发现100个,增强T1WI发现292个,两者共发现298个;增强FLAIR序列发现181个。与增强T1WI相比,仅增强FLAIR序列显示的35个转移灶中,26个位于皮层或皮层下;2个小脑半球灶直径达14mm,余33个直径均<5mm。受血管结构的影响,增强T1WI上7个病灶假阳性,9个为假阴性,而在增强FLAIR序列上均明确诊断。在T1WI上肿瘤的强化程度和强化百分比高于FLAIR序列,而肿瘤与白质、肿瘤与脑脊液的CR和CNR则以FLAIR序列为高,增强T1WI和增强FLAIR序列上的转移瘤体积平均为(4.2±6.2)cm3和(4.0±6.5)cm3,两者差异无统计学意义。结论增强FLAIR序列在脑转移瘤的诊断中有一定的价值,尤其是对位于皮层表面的病灶,其与增强T1WI具有很好的互补性。

Objective To discuss the clinic value of enhanced FLAIR imaging in the brain metastases by comparing with non-enhanced FLAIR and enhanced T1WI. Materials and Methods 20 patients with brain metastases were performed FLAIR and spin-echo T1WI with and without intravenous gndopentetate dimeglumine. Number, volume, degree and percent of increase in signal intensity of metastases, contrast ratio and contrast-to-noise ratio （CNR） of tumor-to-white matter and tumor-to-CSF were measured in FLAIR and T1WI images. Results 1 patients displayed 3 lesions only on postcontrast T1WI, the remnant 19 patients had 327 lesions, postcontrast T1WI and non-enhanced FLAIR images respectively discovered 292 and 100 lesions, and both of them discovered 298 lesions; enhanced FLAIR images discovered 181 lesions. Compared with postcontrast T1WI, 35 lesions were displayed only on postcontrast FLAIR images, 26 lesions located at cortex or subcortex; the size of 2 eerebellar hemisphere lesions arrived 14 mm, but the size of the others was smaller than 5mm. Influenced by blood vessel, there were 7 false positive lesions and 9 false negative lesions on postcontrast T1WI, but all of them were identified on postcontrast FLAIR images. Although the degree and percent of increase in tumor signal intensity was lower than that on T1WI, FLAIR images had higher CR and CNR of tumor-to-background and tumor-to-CSF. Tumor volume were 4.2 cm^3 ± 6.2 and 4.0 cm^3 ± 6.5 on pesteontrast T1WI and FLAIR images respectively, which had no statistically different between two groups. Conclusion Enhanced FLAIR imaging has some value in showing brain metastases, especially lesions in the surface of cortex, and which have complementary effect to postcontrast T1 WI.