Herpes simplex encephalitis |
Bilateral, asymmetric T2/FLAIR hyperintensity in the temporal lobes |
Cortical hemorrhage, gyriform enhancement, and restricted diffusion on DWI |
Hypoperfusion |
Reduced NAA/Cr ratio and increased Cho/Cr ratio. There can be Lip and Lac(22 Hitosugi M, Ichijo M, Matsouka Y, et al. Proton MR spectroscopy findings in herpes simplex encephalitis. Rinsho Shinkeigaku. 1996;36:839-43.,33 Demaerel P, Wilms G, Robberecht W, et al. MRI of herpes simplex encephalitis. Neuroradiology. 1992;34:490-3.)
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Neurotuberculosis |
Enhancement of leptomeninges and dura mater, tuberculomas |
Hydrocephalus, ventriculitis, vasculitis, infarction, venous thrombosis, neuropathies |
Variable |
Lip and Lac peak(44 Khatri GD, Krishnan V, Antil N, et al. Magnetic resonance imaging spectrum of intracranial tuberculous lesions: one disease, many faces. Pol J Radiol. 2018;83:e524-e535.,55 Mader I, Rauer S, Gall P, et al. (1)H MR spectroscopy of inflammation, infection and ischemia of the brain. Eur J Radiol. 2008;67:250-7.)
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Limbic encephalitis |
Bilateral, asymmetric T2/FLAIR hyperintensity in mesial temporal structures |
Involvement of basal ganglia, enhancement, and restricted diffusion on DWI |
Hypoperfusion |
Reduced NAA. Increased Cho, Lac, and MI(66 Isik N, Candan F, Dincer A, et al. Serial cranial MR imaging and single voxel proton MR spectroscopy in paraneoplastic limbic encephalitis. Eur J Radiol Extra. 2004;50:1-7.)
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Alzheimer's disease |
Reduction in the volume of the mesial temporal structures (especially the hippocampus) disproportional to the atrophy in the remaining parenchyma |
Atrophy of the superior parietal lobule |
Hypoperfusion |
Reduced NAA and NAA/Cr ratio in the cingulate gyrus and hippocampi. Increased MI/Cr ratio in the cingulate gyrus and parietal cortex(77 Kantarci K. Magnetic resonance spectroscopy in common dementias. Neuroimaging Clin N Am. 2013;23:393-406.)
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Frontotemporal dementia |
Selective atrophy of the frontal or temporal lobes |
Atrophy predominantly on the left in primary progressive aphasia |
Hypoperfusion |
Reduced NAA/Cr ratio and increased MI/ Cr ratio in the frontal cortex(77 Kantarci K. Magnetic resonance spectroscopy in common dementias. Neuroimaging Clin N Am. 2013;23:393-406.)
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Mesial temporal sclerosis |
T2/FLAIR hyperintensity in the hippocampus with loss of volume and dilatation of the temporal horn (bilateral in 10% of cases) |
Atrophy of the amygdala, fornix, mammillary body and entorhinal cortex. Loss of cortical/subcortical differentiation in the temporal pole |
Hypoperfusion |
Reduced NAA in the affected temporal lobe and in the hippocampus(88 Capizzano AA, Vermathen P, Laxer KD, et al. Multisection proton MR spectroscopy for mesial temporal lobe epilepsy. AJNR Am J Neuroradiol. 2002;23:1359-68.)
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Cerebrovascular disease |
Loss of cortical/subcortical differentiation in the involved vascular territory. T2/FLAIR hyperintensity. Early restricted diffusion on DWI |
Hyperdense artery sign, gyriform enhancement |
Hypoperfusion |
In the acute phase, there is increased Cho, Lip, and Lac, with reduced NAA(55 Mader I, Rauer S, Gall P, et al. (1)H MR spectroscopy of inflammation, infection and ischemia of the brain. Eur J Radiol. 2008;67:250-7.,99 Faria AV, Reis F, Zanardi VA, et al. The pattern of proton magnetic resonance spectroscopy in non-neoplastic encephalic lesions. Arq Neuropsiquiatr. 2004;62:429-36.)
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Kernicterus |
T2/FLAIR hyperintensity with hippocampal atrophy in the chronic phase |
Change in the signal of the globus pallidus and subthalamic nuclei |
Hypoperfusion |
Increased Tau, Glx, and MI, with reduced Cho(1010 Oakden WK, Moore AM, Blaser S, et al. 1H MR spectroscopic characteristics of kernicterus: a possible metabolic signature. AJNR Am J Neuroradiol. 2005;26:1571-4.)
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Megalencephalic leukoencephalopathy with subcortical cysts |
Diffuse hyperintense signal of deep white matter sparing basal ganglia and cerebellum |
Subcortical cysts evident initially in the temporal lobes and later in the frontal and parietal lobes |
Hypoperfusion |
Increased Cho and MI, with reduced NAA, in the early stage. Increased Lac in the advanced stage(1111 Reis F, Kido RYZ, Mesquita JA, et al. Megalencephalic leukoencephalopathy with subcortical cysts (MLC) - a case with clinical and magnetic resonance imaging (MRI) dissociation. Arq Neuropsiquiatr. 2015;73:171-2.)
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Lowgrade diffuse astrocytoma |
T1 hypointensity and T2/FLAIR hyperintensity, infiltration of the cortex, no enhancement, and no restricted diffusion on DWI |
No evidence of necrosis or hemorrhagic components |
Hypoperfusion (rCBV < 1.75). Hyperperfusion if anaplastic/ high grade |
Increased MI, slightly increased Cho (Cho/Cr ratio < 2), reduced NAA, and absence of Lac(33 Demaerel P, Wilms G, Robberecht W, et al. MRI of herpes simplex encephalitis. Neuroradiology. 1992;34:490-3.)
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Lymphoma |
T2/FLAIR hypointensity with restricted diffusion on DWI. Intense, homogeneous enhancement |
In immunocompetent patients, a necrotic component is rarely seen |
Hypoperfusion |
Increased Cho, Lip, and Lac. Reduced NAA(1212 Reis F, Schwingel R, Nascimento FBP. Central nervous system lymphoma: iconographic essay. Radiol Bras. 2013;46:110-6.)
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