Neuroimaging in Zoonotic Outbreaks Affecting the Central Nervous System: Are We Fighting the Last War?

When preparing for the coronavirus disease 2019 pandemic and its effects on the CNS, radiologists should be familiar with neuroimaging appearances in past zoonotic infectious disease outbreaks. Organisms that have crossed the species barrier from animals to humans include viruses such as Hendra, Nipah, Severe Acute Respiratory Syndrome, and influenza, as well as bacteria and others. Brain CT and MR imaging findings have included cortical abnormalities, microinfarction in the white matter, large-vessel occlusion, and features of meningitis. In particular, the high sensitivity of diffusion-weighted MR imaging in detecting intracranial abnormalities has been helpful in outbreaks. Although the coronaviruses causing the previous Severe Acute Respiratory Syndrome outbreak and the current coronavirus disease 19 pandemic are related, it is important to be aware of their similarities as well as potential differences. This review describes the neuroimaging appearances of selected zoonotic outbreaks so that neuroradiologists can better understand the current pandemic and potential future outbreaks.

Creutzfeldt-Jakob disease: which diffusion-weighted imaging abnormality is associated with periodic EEG complexes?

BACKGROUND: Clinical diagnosis of CJD remains important due to lack of access to a genetic or histopathological diagnosis. Using current WHO criteria, diagnostic certainty can be increased from "possible" to "probable" CJD if periodic complexes are recorded on EEG. OBJECTIVE: To study the correlation between patterns of MRI-DWI hyperintensity and typical EEG findings among patients with CJD. METHODS: Demographics, clinical findings, MRI-DWI and EEG findings of CJD patients were retrospectively reviewed. RESULTS: A total of 14 patients ranging in age from 35 to 81 years were identified. All had dementia and cerebellar ataxia. Psychiatric manifestations were seen in 5 patients. Seven patients had both cortical and striatal DWI changes, five had isolated cortical DWI changes and two had isolated striatal DWI changes. All twelve patients with cortical DWI changes also had periodic EEG changes. In ten, periodic EEG was recorded within seven days of the DWI. The two patients with isolated striatal DWI changes did not develop periodic EEG complexes despite serial EEG recordings, 40 and 88 days from their respective DWI scans. CONCLUSIONS: Serial EEGs are not useful for patients with isolated striatal DWI hyperintensity but will increase diagnostic certainty from "possible" to probable" CJD for patients with cortical DWI hyperintensity.

Craniospinal dissemination in teratocarcinosarcoma.

There have been fewer than 60 cases of malignant teratocarcinosarcoma (TCS) described in the literature, usually arising in the nose and paranasal sinuses. The authors report on a patient who presented with neurological symptoms caused by a frontal lobe TCS, and in whom widespread spinal tumor dissemination developed. In rare cases, TCSs can occur with a predominantly cranial and neurological presentation and spread to the spinal canal.

Giant spinal ganglioneuroma.

Ganglioneuromas are rare benign tumours, which may affect any part of the spine and spinal cord. They occasionally grow to a large size but total excision using microsurgical techniques is often possible, and may be curative. This case report illustrates the clinical and histopathological features of two rare giant ganglioneuromas of the spinal cord.

MRI features in children with desmoplastic medulloblastoma.

Desmoplastic medulloblastoma (DMB) is a variant that has a more favorable prognosis compared to classical medulloblastoma, but its MRI features have not been as well described. We retrospectively reviewed the MRI features in children with pathologically proven DMB, including T2-weighted, fluid-attenuated inversion recovery (FLAIR) and contrast enhanced images, with isotropic diffusion-weighted (DW) MRI also performed in some patients. There were 16 tumors in 12 patients; one patient had five discrete lesions. In all patients, the tumor involved the cerebellar vermis, with nine lesions showing multiple peripheral small cysts. In nine of 16 tumors, there were focal areas of isointensity or hypointensity on T2-weighted or FLAIR images; seven of these showed corresponding focal enhancement. There was also one patient with radiating star-shaped enhancement in two lesions, and a multi-nodular enhancing pattern was observed in another patient. Low apparent diffusion coefficient (ADC) values were found in the lesions studied by DW MRI in five patients. DMB may have a typical imaging appearance of peripheral cysts, decreased ADC and focal enhancing areas corresponding to focal isointense or hypointense signal on T2-weighted and FLAIR images. Although these MRI features may distinguish this variant of medulloblastoma, multinodular or star-shaped radiating enhancement may also be detected in some patients.

Lacrimal glands: size does matter!

A 40-year-old woman presented with vague headaches and blurred vision. Contrast-enhanced magnetic resonance imaging of the brain revealed bilaterally symmetrical diffuse enlargement of the lacrimal glands. A fine needle biopsy of the lacrimal gland was consistent with sarcoidosis. Although, isolated lacrimal gland involvement is rare, it may be the initial clinical presentation of sarcoidosis, as seen in this patient. Imaging plays a vital role in these unsuspected cases and careful evaluation of the lacrimal glands with dedicated thin section, fat suppressed, axial and coronal orbital imaging, may help identify a pathological cause and avoid a delay in diagnosis.

Functional Imaging: Dynamic Contrast-Enhanced CT using a Distributed-Parameter Physiologic Model for Accessing Stroke and Intracranial Tumor.

Functional imaging has the potential to be a practical and widely-available method of studying the pathphysiology of disease using modern CT and MRI technologies. With the high temporal resolution achievable by these technologies, a two-compartment distributed-parameter model, which more accurate represents the tracer concentration within the vascular space, was applied on two patients' data with intracranial tumor and stroke. The parametric maps successfully generated were more informative than the current commercial software packages and the commonly used lumped-parameter compartmental models.

Dynamic contrast-enhanced CT of intracranial meningioma: comparison of distributed and compartmental tracer kinetic models--initial results.

Dynamic contrast material-enhanced computed tomographic images of intracranial meningioma were analyzed by using both distributed-parameter and conventional compartmental tracer kinetic models. The distributed-parameter models were found to yield consistently better fitting of data sets than were conventional compartmental models. Although linear correlations were found between the kinetic parameters of the two models, some of these parameters (such as perfusion and mean transit time) did not correspond quantitatively. For all models, the kinetic parameters associated with the extravasation of tracer were found to be distinctly higher in meningiomas than in normal white- and gray-matter tissues.