An Approach. to Brain. Infection. 37F found down. Disclosures. Approach to CNS Infection. Objectives. Parenchymal. None.

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1 An Approach Disclosures to Brain None. Infection Jason Shewchuk, MD Clinical Associate Professor Head of Neuroradiology UBC European Course in Neuroradiology 2018 Objectives Following this session the participant will: Recognize classic and important brain infections at imaging Be able to differentiate important brain infectious processes from their mimics Approach to CNS Infection Classic and Important Abscess, HSV, TB, Cysticercosis, CJD, Opportunistic Infections, Mycotic Aneurysm Mimics of Infection Abscess vs GBM/met/TDL, HSV vs LE, Toxo vs PCNSL Parenchymal Pyogenic Cerebritis to Abscess - stages Viral Encephalitis TB/Fungal Parasitic 37F found down

2 NCCT CECT Gd ADC Abscess (IVDU) 71M with headache and seizures ADC Gd Gd

3 Abscess Abscess Extension from Sinusitis Hematogenous, penetrating inj, direct ext Early cerebritis 3-5 days Edema, restricted diffusion, +/- patchy enh Late cerebritis day 4-5, for days Irreg rim enhancement, restricted diffusion Early Capsule 2 weeks, for 1-2 months Thin smooth high low rim, restr diff Late Capsule weeks to months Collapsed cavity, enhancement 72F with expressive aphasia Herpes Encephalitis Gd ADC

4 68M Found Down Gd Herpes Encephalitis Herpes Encephalitis Headache, low grade fever, altered LOC 95% HSV1 hemorrhagic, necrotizing Affinity for limbic system temporal lobes, insula, inf frontal, cingulate gyri Reactivation latent in trigeminal ganglion DDx: LE, HHV6, GC, CVA, status Immediate IV acyclovir Bilateral, asymmetric medial temporal and insula May extend to inf frontal lobes, cingulate Subtle mass effect CT Normal, or subtle low att MR high signal, restricted diffusion 50% small foci of hemorrhage Mild patchy enhancement

5 Viral Encephalitides CMV PVWM, ependymitis VZV cerebellitis, vasculopathy EBV bilat BG and thalami, splenial WNV bilat BG and thalami, brainstem Restricted diffusion, no enhancement May also have splenial lesion Rabies brainstem, thalami, hippocampi Fulminant, fatal HIV Encephalitis Chronic Encephalitides Central white matter, basal ganglia, cerebellum, brainstem Symmetric PV or diffuse WM disease Atrophy No enhancement SSPE post measles Bilat asymmetric cortical and SCWM, PVWM, and BG signal, diffuse atrophy Rasmussen Encephalitis Normal, then cortical and SCWM signal, unilateral progressive atrophy PML JC virus Bilateral asymmetric JCWM Progressive Multifocal Leukoencephalopathy Gd ADC JC virus polyoma 70-90% population Tropism for oligodendrocytes Subcortical U-fibre involvement scalloped appearance No mass effect or edema Multifocal, rapidly progress to confluent Can improve if immunity recovers Usually no enhancement

6 62M with seizure NCCT CECT Tuberculosis Tuberculoma Variable size, low lesions Variable enhancement, usually ring No restricted diffusion Chronic calcify TB Abscess - rare, actually pseudoabscess High, restricted diffusion, ring enhancement DDx: NCC, abscess, metastases Gd 37F with headache NCCT CECT

7 Aspergillus Gd SWI CNS Fungal Disease IM Candidiasis, Crypto, Mucormycosis N Histo, Blasto, Coccidioido, Aspergillus Diffuse meningitis Parenchymal mass(es) Susceptibility, restricted diffusion Diffuse parenchymal disease Focal dural mass(es) Angioinvasive hemorrhagic infarcts 36F with prior infection Neurocysticercosis Cisterns > parenchyma > ventricles Vesicular cyst with dot Colloidal vesicular enh cyst with edema Granular nodular enh, mild edema Nodular calcified small Ca++ Can have different stages present

8 Classic and Important Abscess Herpes Simplex Encephalitis Tuberculosis Neurocysticercosis Opportunistic Infections Mycotic Aneurysm Creutzfeldt-Jakob Disease Opportunistic Infections Toxo mult ring enh lesions, edema, BG Crypto meningitis, pseudocysts, cryptococcoma, +/- vasculitis CMV PVWM, subependymal enh PML juxtacortical WM, no enh TB meningitis, tuberculoma, abscess 42M with HIV and new onset seizures Gd Toxoplasmosis Toxoplasmosis Commonest opportunistic ID in AIDS CD4<200 Multifocal - BG, thalami, GW jct, CB Nodular and ring enhancement Eccentric target sign Low rcbv Serology 80%, CSF PCR diagnostic DDx PCNSL solitary, higher rcbv

9 71M with sudden headache RICA Lat RICA Oblique Mycotic Aneurysm (Infected Valve)

10 Mycotic Aneurysm Pseudoaneurysm Peripheral Slowly enhancing focus in hematoma IVDU, endocarditis Infarct, abscesses, mycotic aneurysms 74F with dementia ADC Creutzfeldt-Jakob Disease Creutzfeldt-Jakob Disease Rapidly progressive dementia Prion disease, transmissible spongiform encephalopathy (TSE) Proteinaceous infectious particles Misfolded isoform - PrP(C) to PrP(Sc) Sporadic or familial, rare iatrogenic or variant and diffusion cortical, BG, thalami Esp caudate head and putamen Mimics of Infection Abscess vs GBM/Met/TDL HSV vs LE Toxo vs PCNSL Meningitis vs SAH vs LM carcinomatosis Sarcoidosis vs everything

11 Abscess vs Neoplasm Central restricted diffusion Rim high low Low rcbv Thin smooth wall, thinnest to ventricle Necrosis not restricted, rim may be Rim low high High rcbv Thicker irregular wall 43M with left arm weakness Gd 7 months later rcbv ADC

12 Tumefactive Demyelination Gd Tumefactive Demyelination Can mimic abscess or neoplasm Relative lack of mass effect Less edema Horseshoe enhancement Open to cortex Perfusion normal to slightly decreased Medullary veins course through on SWI 64F with STM loss Limbic Encephalitis Gd

13 Limbic Encephalitis Toxo vs Lymphoma Paraneoplastic/autoimmune Bilateral medial temporal, insula, inferior frontal, cingulate High, patchy enhancement Uncommon restr diffusion, hemorrhage Typically small cell lung Ca DDx: Herpes, HHV6, status, GC, CVA Commonest Multiple Slightly restricted Low rcbv Tl SPECT negative PET hypometabolic Second commonest Single More restricted High rcbv Tl SPECT avid PET hypermetabolic Summary Classic and important brain infections at imaging Important brain infectious processes and their mimics