Autoimmune diseases of the brain, imaging and clinical review

Abstract

There is an extensive spectrum of autoimmune entities that can involve the central nervous system, which has expanded with the emergence of new imaging modalities and several clinicopathologic entities. Clinical presentation is usually non-specific, and imaging has a critical role in the workup of these diseases. Immune-mediated diseases of the brain are not common in daily practice for radiologists and, except for a few of them such as multiple sclerosis, there is a vague understanding about differentiating them from each other based on the radiological findings. In this review, we aim to provide a practical diagnostic approach based on the unique radiological findings for each disease. We hope our diagnostic approach will help radiologists expand their basic understanding of the discussed disease entities and narrow the differential diagnosis in specific clinical scenarios. An understanding of unique imaging features of these disorders, along with laboratory evaluation, may enable clinicians to decrease the need for tissue biopsy.

Keywords: Central nervous system; autoimmune brain disease; brain; imaging.

Figure 1.

MS. Axial T2-weighted images show well-circumscribed, ovoid juxtacortical (a) and deep white matter lesions (b) in a patient with MS. Enhancing periventricular lesions in axial post-Gd T1 weighted image (c) indicative of active demyelination. Axial T2 weighted (d), fluid-attenuated inversion recovery (e), and diffusion-weighted imaging (f) show periventricular ovoid lesion without mass effect, with peripheral restricted diffusion in tumefactive MS. Coronal post-Gd T1 weighted image (g) of the same patient shows incomplete rim enhancement. Axial T2-weighted image (h) shows concentric rings of T2 isointensity and hyperintensity related to alternating layers of myelinated and demyelinated brain tissue in Balo Concentric Sclerosis. MS: Multiple sclerosis

Figure 2.

Other demyelinating diseases. Axial T2-weighted (a) and FLAIR (b) images demonstrate several cortical and deep white matter hyperintense lesions in a patient with ADEM. Axial post-Gd T1 weighted image (c) shows peripheral interrupted enhancement in the largest lesion in the right frontal lobe. Sagittal FLAIR (d) shows a typical “snowball” lesion (arrow) in the corpus callosum in a patient with Susac syndrome, which is not a true demyelination, but considered in the differential diagnosis of MS. Axial FLAIR (e) shows extensive confluent white matter hyperintensities, with faint peripheral enhancement in axial post-Gd T1 weighted image (f) in a patient with acute hemorrhagic leukoencephalopathy. Axial FLAIR (g) shows extensive and irregular periventricular hyperintense lesions along the ependymal lining. Axial post-Gd T1 weighted image (h) shows patchy enhancement with blurred margins, typical ‘cloud-like’ enhancement in NMOSD. ADEM: acute demyelinating encephalomyelitis; MS: multiple sclerosis; NMOSD: neuromyelitis optica spectrum disorder

Figure 3.

Predominantly parenchymal (non-demyelinating) involvement. (a, b) Axial FLAIR images demonstrate hyperintensity in bilateral mesial temporal lobes and basal ganglia, in a patient presented with seizure, and subsequently, the presence of anti–N-Methyl-D-aspartate receptor autoantibodies was confirmed. Axial FLAIR (c) and GRE (d) images demonstrate extensive confluent white matter hyperintensities with central linear susceptibility changes due to hemorrhage in a patient diagnosed with hemophagocytic lymphohistiocytosis. Axial T2-weighted (e) image shows subcortical brain edema involving right insular and periinsular regions in acute phase of Rasmussen encephalitis. Axial T2-weighted (f) image from another patient with chronic Rasmussen encephalitis demonstrates right frontal lobe atrophy and loss of parenchymal high signal change. Sagittal post-Gd T1 weighted image (g) shows thickening and enhancement of pituitary stalk as well as enlarged enhancing pituitary gland in lymphocytic hypophysitis. Axial FLAIR (h) image demonstrates subcortical and white matter hyperintensities in the left frontal lobe in a patient with Hashimoto’s meningoencephalitis. Post-Gd T1 weighted image (i) shows faint marginal enhancement in the left frontal lesion (arrow).

Figure 4.

Predominantly parenchymal (non-demyelinating) involvement (continued). (a) Axial FLAIR image shows scattered hyperintense foci in the subcortical area and bilateral basal ganglia with patchy areas of enhancement in axial post-Gd T1 weighted image (b) and a focus of restricted diffusion in the corpus callosum in DWI (c) (several other foci of restricted diffusion, not shown) representing acute cerebritis/vasculitis in SLE. Axial FLAIR images (d, e) from another patient with SLE show diffuse fulminant edema in bilateral centrum semiovale and cerebellar white matter. DWI: diffusion-weighted images; SLE: systemic lupus erythematosus

Figure 5.

Predominantly meningeal-involving diseases. (a) Axial T2 weighted image reveals nodular T2 hypointense dural thickening and adjacent brain parenchymal edema in neurosarcoidosis. (b) Post-Gd T1 weighted image shows corresponding dural enhancement. (c) Axial FLAIR image in another patient with neurosarcoidosis shows leptomeningeal thickening, adjacent brain parenchymal edema and leptomeningeal enhancement in post-Gd T1 weighted image (d). (e) Coronal post-Gd T1 weighted image shows lepto and pachymeningeal enhancement in rheumatoid arthritis. (f) Coronal post-Gd T1 weighted image shows mostly leptomeningeal enhancement in IgG4-related disease. Granulomatosis with polyangiitis evidenced by hyperdense right tentorial thickening in non-contrast CT scan (g) and corresponding T2 hypointense right tentorial thickening in axial T2 weighted image (h). Axial and coronal post-Gd T1 weighted images (I, J) of the same patient show enhancement of bilateral tentorial leaflets.

Figure 6

Brain stem and posterior fossa. (a, b, c) Axial T2 weighted, FLAIR, and post-Gd T1 weighted images reveal hyperintense foci in bilateral middle cerebellar peduncles and corresponding punctate foci of enhancement in CLIPPERS. (d) Axial FLAIR image reveals the acute phase of paraneoplastic cerebellitis with right cerebellar involvement. Axial FLAIR (e) shows a focal hyperintense lesion in the left cerebellar peduncle and patchy enhancement in post-Gd T1 weighted image (f) in Neuro-Behçet’s disease. CLIPPERS: chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroid