Gupta R K, Kathuria M K, Pradhan S
Department of Radiology, Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Lucknow, India.
AJNR Am J Neuroradiol. 1999 May;20(5):867-75.
CNS tuberculosis may simulate other granulomas and meningitis on MR images. The purpose of this study was to improve the characterization of lesions in CNS tuberculosis and to assess the disease load using magnetization transfer (MT) imaging.
A total of 107 tuberculomas in seven patients with or without meningitis and 15 patients with tuberculosis meningitis alone were studied. Fifteen patients with cysticercus granulomas with T2 hypointensity, five patients each with viral and pyogenic meningitis, and two patients with cryptococcal meningitis were also studied. The MT ratios were calculated from tuberculomas, cysticercus granulomas, and thickened meninges in tuberculous, viral, pyogenic, and cryptococcal meningitis and were compared within each pathologic group and with the MT ratio of different regions of normal brain parenchyma. Detectability of lesions on T1-weighted MT spin-echo (SE) images was compared with that on conventional SE and postcontrast MT-SE images.
Thickened meninges appeared hyperintense relative to surrounding brain parenchyma in the basal and supratentorial cisterns on precontrast MT-SE images in all 18 patients with tuberculosis meningitis. These meninges were not seen or were barely visible on conventional SE images, and enhanced on postcontrast MT-SE images. The MT ratio from the thickened meninges of tuberculous meningitis was significantly lower than that from the meninges in cryptococcal and pyogenic disease and significantly higher than the meninges in viral meningoencephalitis. The MT ratio from T2 visible and invisible tuberculomas appeared to be significantly lower than that of normal white matter. The MT ratio of T2 hypointense cysticercus granuloma was significantly higher than that of T2 hypointense tuberculoma.
Precontrast MT-SE imaging helps to better assess the disease load in CNS tuberculosis by improving the detectability of the lesions. With the use of MT ratios, it may be possible to differentiate tuberculosis from similar-appearing infective lesions on MR images.
中枢神经系统结核在磁共振成像（MR）上可能类似其他肉芽肿和脑膜炎。本研究的目的是改善中枢神经系统结核病变的特征描述，并使用磁化传递（MT）成像评估疾病负荷。
共研究了7例有或无脑膜炎的患者中的107个结核瘤以及15例仅患有结核性脑膜炎的患者。还研究了15例具有T2低信号的囊尾蚴肉芽肿患者、5例分别患有病毒性和化脓性脑膜炎的患者以及2例患有隐球菌性脑膜炎的患者。计算结核性、病毒性、化脓性和隐球菌性脑膜炎中结核瘤、囊尾蚴肉芽肿和增厚脑膜的MT比率，并在每个病理组内进行比较，同时与正常脑实质不同区域的MT比率进行比较。比较T1加权MT自旋回波（SE）图像上病变的可检测性与传统SE图像和对比剂增强后MT-SE图像上病变的可检测性。
在所有18例结核性脑膜炎患者的对比剂增强前MT-SE图像上，基底池和幕上池的增厚脑膜相对于周围脑实质呈高信号。这些脑膜在传统SE图像上未见或仅隐约可见，在对比剂增强后MT-SE图像上强化。结核性脑膜炎增厚脑膜的MT比率明显低于隐球菌性和化脓性疾病脑膜的MT比率，且明显高于病毒性脑膜脑炎脑膜的MT比率。T2可见和不可见结核瘤的MT比率似乎明显低于正常白质的MT比率。T2低信号囊尾蚴肉芽肿的MT比率明显高于T2低信号结核瘤的MT比率。
对比剂增强前MT-SE成像通过提高病变的可检测性有助于更好地评估中枢神经系统结核的疾病负荷。利用MT比率，有可能在MR图像上区分结核与外观相似的感染性病变。
