Joy Lynn, Sakalecha Anil K
Radiodiagnosis, Sri Devaraj Urs Medical College, Kolar, IND.
Cureus. 2023 May 14;15(5):e39003. doi: 10.7759/cureus.39003. eCollection 2023 May.
The two most common infectious causes of ring-enhancing lesions are neurocysticercosis (NCC) and tuberculoma. It is a challenge to differentiate NCC and tuberculomas radiologically since they show the same imaging findings on computed tomography (CT). Hence, this study was performed to assess the role of magnetic resonance imaging (MRI) as an additional advanced modality to aptly characterize the lesion. Conventional MRI with additional advanced imaging sequences like diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC), magnetic resonance spectroscopy (MRS), and post-contrast T1-weighted imaging (T1WI) aids in characterizing the lesion and helps in differentiating NCC and tuberculomas.
To compare the findings of DWI, ADC cut-off values, spectroscopy, and contrast-enhanced MRI in differentiating NCC from tuberculoma.
Individuals who matched the inclusion criterion underwent an MRI of the brain (plain and contrast) in a 1.5 Tesla, 18-channel, magnetic resonance scanner (Magnetom Avanto®, Siemens Healthineers, Erlangen, Germany). The following imaging sequences were included: T1WI (axial and sagittal), T2-weighted imaging (axial and coronal), fluid-attenuated inversion recovery, DWI at 0, 500, and 1000 mm/s b-values with corresponding ADC values, and single-voxel MRS. Based on MRI features such as number, size, location, margins of lesions, scolex, surrounding edema, DWI features with corresponding ADC values, enhancement pattern of lesions, and spectroscopy findings, we evaluated and differentiated the lesions as NCC or tuberculoma. Radiological diagnoses were correlated in terms of clinical symptoms and response to treatment.
In our study, 42 subjects were included, of which the total number of NCC cases was 25 (59.52%) and tuberculoma was 17 (40.47%). The mean age of patients included was 42.85 ± 14.76 years (21 to 78 years). On post-contrast imaging, all 25 cases of NCC (100%) showed thin ring enhancement whereas the majority of tuberculomas (64.7%) showed thick irregular ring enhancement. On MRS, all 25 cases (100%) of NCC showed an amino acid peak and all 17 cases (100%) of tuberculoma showed a lipid lactate peak. On DWI, out of 25 NCC cases, restriction of diffusion was absent in the majority of cases (88%) and out of 17 cases of tuberculoma, restriction of diffusion was present in 12 cases (70.5%) (T2 hyperintense tuberculoma, indicative of caseating tuberculoma with central liquefaction) and was absent in the rest. In our study, the mean ADC value of NCC lesions (1.30 ± 0.137 x 10 mm/s) was found to be greater than that of tuberculoma (0.74 ± 0.090 x 10 mm/s). ADC value of 1.2 x 10 was obtained as a cut-off to differentiate NCC and tuberculoma. The ADC cut-off value of 1.2 x 10 mm/s showed a sensitivity of 92% and specificity of 94.1% in differentiating NCC from tuberculoma.
Conventional MRI with additional advanced imaging sequences like DWI, ADC, MRS, and post-contrast T1WI aids in characterizing the lesion and thereby helps in differentiating NCC and tuberculomas. Hence, multiparametric MRI assessment is useful in making a prompt diagnosis and eliminating the need for a biopsy.
环形强化病灶最常见的两种感染性病因是神经囊尾蚴病（NCC）和结核瘤。在放射学上区分NCC和结核瘤具有挑战性，因为它们在计算机断层扫描（CT）上显示相同的影像学表现。因此，本研究旨在评估磁共振成像（MRI）作为一种额外的先进检查手段在准确鉴别病灶方面的作用。采用常规MRI并结合扩散加权成像（DWI）、表观扩散系数（ADC）、磁共振波谱（MRS）和增强后T1加权成像（T1WI）等额外的先进成像序列，有助于对病灶进行特征性描述，并有助于区分NCC和结核瘤。
比较DWI、ADC临界值、波谱分析和增强MRI在鉴别NCC与结核瘤中的表现。
符合纳入标准的个体在一台1.5特斯拉、18通道的磁共振扫描仪（德国西门子医疗公司的Magnetom Avanto®）上接受脑部MRI检查（平扫及增强）。检查序列包括：T1WI（轴位和矢状位）、T2加权成像（轴位和冠状位）、液体衰减反转恢复序列、b值为0、500和1000 mm/s的DWI及其相应的ADC值，以及单体素MRS。根据病灶的数量、大小、位置、边缘、头节、周围水肿、具有相应ADC值的DWI表现、病灶的强化方式以及波谱分析结果等MRI特征，对病灶进行评估并区分为NCC或结核瘤。将放射学诊断与临床症状及治疗反应进行关联分析。
本研究共纳入42例受试者，其中NCC病例25例（59.52%），结核瘤17例（40.47%）。纳入患者的平均年龄为42.85±14.76岁（21至78岁）。增强后成像显示，所有25例NCC（100%）均表现为薄壁环形强化，而大多数结核瘤（64.7%）表现为厚壁不规则环形强化。MRS检查中，所有25例NCC（100%）均显示氨基酸峰，所有17例结核瘤（100%）均显示脂质乳酸峰。DWI检查中，25例NCC病例中，大多数病例（88%）无扩散受限，17例结核瘤病例中，12例（70.5%）（T2高信号结核瘤，提示干酪样结核瘤伴中央液化）有扩散受限，其余病例无扩散受限。本研究中，NCC病灶的平均ADC值（1.30±0.137×10⁶mm²/s）高于结核瘤（0.74±0.090×10⁶mm²/s）。以1.2×10⁶作为区分NCC和结核瘤的临界ADC值。该ADC临界值在区分NCC与结核瘤时，敏感性为92%，特异性为94.1%。
采用常规MRI并结合DWI、ADC、MRS和增强后T1WI等额外的先进成像序列，有助于对病灶进行特征性描述，从而有助于区分NCC和结核瘤。因此，多参数MRI评估有助于快速做出诊断，无需进行活检。
