Aprile I, Iaiza F, Lavaroni A, Budai R, Dolso P, Scott C A, Beltrami C A, Fabris G
Department of Neuroradiology, S. Maria della Misericordia General Hospital, Udine, Italy.
AJNR Am J Neuroradiol. 1999 Aug;20(7):1259-67.
T1-, T2-, and proton density (PD)-weighted sequences are used to characterize the content of cystic intracranial lesions. Fluid-attenuated inversion recovery (FLAIR) MR sequences produce T2-weighted images with water signal saturation. Therefore, we attempted to verify whether FLAIR, as compared with conventional techniques, improves the distinction between intracranial cysts with a free water-like content versus those filled with a non-free water-like substance and, consequently, aids in the identification of these lesions as either neoplastic/inflammatory or maldevelopmental/porencephalic.
Forty-five cystic intracranial lesions were studied using T1-weighted, T2-weighted, FLAIR, and PD-weighted sequences. By means of clustering analysis of the ratio in signal intensity between the cystic intracranial lesions and CSF, the intracranial lesions were classified as filled with a free water-like content or with a non-free water-like substance. The results were compared with their true content as evaluated either histologically or on the basis of clinical, neuroradiologic, and follow-up features (necrotic material, 13 cases; accumulation of intercellular proteinaceous/myxoid material, eight cases; keratin, five cases; CSF, 19 cases). Cystic intracranial lesions were divided into two clinical groups, neoplastic/inflammatory and maldevelopmental/porencephalic, to evaluate the level of accuracy of each MR technique. The difference in absolute value signal intensity between CSF and cystic intracranial lesion content was calculated on FLAIR and PD-weighted images.
PD-weighted and FLAIR sequences, unlike T1- and T2-weighted sequences, accurately depicted all cystic intracranial lesions containing necrotic or myxoid/proteinaceous intercellular material (non-free water-like) and most CSF-containing cystic intracranial lesions (free water-like). All imaging techniques inaccurately showed some of the keratin-containing cystic intracranial lesions and pineal cysts. The overall error rate was 22% for T1-weighted, 27% for T2-weighted, 9% for FLAIR, and 13% for PD-weighted sequences. The signal intensity difference between CSF and cystic intracranial lesion content was higher with FLAIR imaging.
FLAIR imaging depicts far more accurately the content of cystic intracranial lesions and better reveals the distinction between maldevelopmental/porencephalic and neoplastic/inflammatory lesions than do conventional sequences. FLAIR has the added advantage of a higher signal intensity difference between cystic intracranial lesions and CSF.
T1加权、T2加权和质子密度（PD）加权序列用于表征颅内囊性病变的内容物。液体衰减反转恢复（FLAIR）磁共振序列产生水信号饱和的T2加权图像。因此，我们试图验证与传统技术相比，FLAIR是否能更好地区分具有游离水样内容物的颅内囊肿与充满非游离水样物质的囊肿，从而有助于将这些病变识别为肿瘤性/炎症性或发育异常性/脑穿通性囊肿。
使用T1加权、T2加权、FLAIR和PD加权序列对45例颅内囊性病变进行研究。通过对颅内囊性病变与脑脊液信号强度比值的聚类分析，将颅内病变分为充满游离水样内容物或非游离水样物质。将结果与其通过组织学评估或基于临床、神经放射学及随访特征（坏死物质，13例；细胞间蛋白质/黏液样物质积聚，8例；角蛋白，5例；脑脊液，19例）所确定的真实内容进行比较。将颅内囊性病变分为肿瘤性/炎症性和发育异常性/脑穿通性两个临床组，以评估每种磁共振技术的准确性水平。在FLAIR和PD加权图像上计算脑脊液与颅内囊性病变内容物之间的绝对值信号强度差异。
与T1加权和T2加权序列不同，PD加权和FLAIR序列准确描绘了所有含有坏死或黏液样/蛋白质细胞间物质（非游离水样）的颅内囊性病变以及大多数含脑脊液的颅内囊性病变（游离水样）。所有成像技术都未能准确显示一些含角蛋白的颅内囊性病变和松果体囊肿。T1加权序列的总体错误率为22%，T2加权序列为27%，FLAIR序列为9%，PD加权序列为13%。FLAIR成像时脑脊液与颅内囊性病变内容物之间的信号强度差异更大。
与传统序列相比，FLAIR成像能更准确地描绘颅内囊性病变的内容物，更好地揭示发育异常性/脑穿通性病变与肿瘤性/炎症性病变之间的差异。FLAIR的另一个优势是颅内囊性病变与脑脊液之间的信号强度差异更大。
