增强后液体衰减反转恢复序列MRI在颅内肿瘤诊断中的应用

目的 评价增强后液体衰减反转恢复序列（FLAIR）在颅内肿瘤诊断中的应用价值。方法 104例颅内肿瘤，经手术、病理证实共有病灶124个。分别行增强前、后T1WI和FLAIR扫描。由2名有经验的放射科医生对所有病例进行评价。评价内容包括：增强例数、增强病灶个数及强化病灶部位；对比度及增强率；病变大小和范围。结果行统计学分析。结果 104例中，增强后FLAIR（CEFLAIR）成像、增强SE T1WI（CET1WI）均显示98例有强化。CEFLAIR成像检出了117个强化灶，CE T1W1检出了120个。4个病灶仅在CEFLAIR显示而CET1WI未显示。另有7个病灶仅在CET1WI显示而CEFLAIR未显示。两者之信噪比（SNR）差异无统计学意义（t=1．10，P=0．270），脑灰白质对比度（GMC）、对比噪声比（CNR）及强化率（CER）差异均有统计学意义（t值分别为2．46、7．10、9．67，P值分别为0．015、0．000、0．000）。在显示病灶大小上，CEFLAIR成像明显大于CET1WI（t=4．13，P=0．000），在病灶范围上，有62例CEFLAIR成像较CET1WI大。CEFLAIR成像对位于脑沟、凸面、侧脑室旁及侧脑室内病灶的检出优于CET1WI，而对大脑半球及第四脑室内的病灶的显示不如CET1WI。结论 CEFLAIR成像与CET1WI比较，强化病灶数，两者无明显差别，强化程度CET1WI明显高于CEFLAIR成像，但两者对不同部位病灶的显示有明显差异，CEFLAIR成像显示病灶大小和范围明显大于CET1WI。两种序列相互补充，建议将CEFLAIR成像序列列为增强后常规序列。

Usefulness of contrast-enhanced FLAIR MRI in the diagnosis of intracranial tumors

Objective To determine the clinical utility of Gadolinium-enhanced fast fluid-attenuated inversion-recovery(FLAIR) MR imaging in the diagnosis of intracranial tumors. Methods One hundred and four consecutive patients with intracranial tumors referred for gadolinium-enhanced brain MR imaging including FLAIR and T_1-weighted MR imaging pre- and post- administration of Gd-DTPA. The contrast-enhanced FLAIR(CE FLAIR) and T_1-weighted spin-echo MR images were evaluated independently by two radiologists for the number of examinations with one or more enhancing lesions, the number and location of enhancing lesions per examinations, signal-to-noise ratio(CNR) and contrast-enhancement ratio(CER) of lesions, size and extent of enhancing lesions. Results In 98 of 104 patients, we saw enhancing lesions both on the FLAIR and T_1W images. More lesions were seen on enhanced T_1WI(n=120) than those on the enhanced FLAIR sequence(n=117),which did not show statistical significance between the two sequences(P>0.05). Four lesions were only revealed on CE FLAIR whereas 7 lesions were only found on postcontrast T_1WI. Enhancing lesions located in cerebral hemisphere or the forth ventricle was revealed much more on T_1WI than that on CE FLAIR. However, postcontrast fast FLAIR images may be useful in detecting superficial abnormalities and those located in sulcus or lateral ventricle. The enhancement degree of enhanced T_1WI was much more intense than that of CE FLAIR(P<0.01). There were no statistical significance in SNR(P>0.05) and statistical significance in GWC, CNR and CER(P<0.05) of the both sequences. The size and extent of lesions on CE FLAIR images were significantly larger than that on postcontrast T_1WI(P<0.01). Conclusion Gadolinium-enhanced FLAIR and T_1-weighted spin-echo MR images may complement each other in detecting intracranial tumors and the CE FLAIR should be selected to the routine MRI sequence.