Fig. 6: General imaging patterns of fungal neuroinfection
References: https://www.semanticscholar.org/paper/Advances-in-the-diagnosis-and-treatment-of-fungal-Schwartz-Kontoyiannis/646131536127a6292dd3656376e07d2b8aa9c6a7
SPECIFIC IMAGING FINDINGS
YEASTS
1. Neurocandidiasis:
- Candidiasis: most common nosocomial fungal infection worldwide.
- Most common intrauterine/neonatal fungal infection
- C Albicans - normal constituent of human gut flora
- Susceptible individuals –> Disseminated haematogenous infection
Fig. 7: Spectrum of Neurocandidiasis
Fig. 8: CANDIDA MICROABSCESS
Imaging Pearls: Scattered T1 hyperintense, diffusion restricting foci without SWI blooming in basal ganglia and subcortical region in a neonate is the most common presentation of candida microabscess
2. CNS Cryptococcosis
- C. neoformans
- most common fungal infection and second most common opportunistic infection of the central nervous system
- commonly found in soil, especially with pigeon and avian droppings. Infection is acquired by inhaling spores of fungus.
- often cause symptomatic pulmonary infections and then often disseminate to the central nervous system, skin, and bones.
Fig. 9: Spectrum of CNS Cryptococcosis
Fig. 10: CNS Cryptococcosis
Fig. 11: CNS Cryptococcosis
Imaging pearls: Subtle leptomeningeal enhancement, Prominent VR spaces, T2/FLAIR hyperintense foci in basal ganglia in a immunocompromised patient need consideration for cryptococcosis.
Beware of increase in lesions after treatment due to immune reconstitution inflammatory syndrome (IRIS).
FILAMENTOUS FUNGI:
1. CNS Aspergillosis
- Aspergillus fumigatus - most common species
- Saprophytic opportunistic fungus found in soil and on plants.
- The lungs are the primary site of infection, through inhalation of spores.
- CNS involvement is by either haematogenous dissemination or direct extension from PNS/ mastoids
- Angioinvasive - due to enzyme Elastase
Fig. 12: Spectrum of CNS Aspergillosis
Fig. 13: Aspergillus Abscess
Fig. 14: Aspergillus Abscess
Fig. 15: Invasive Aspergillus otomastoiditis
Fig. 16: Rhinocerebral Aspergillosis
Fig. 17: Aspergillus skull base osteomyelitis with vascular invasion
Imaging Pearls:
- Peripheral and intracavitory diffusion restriction
- Hemorrhagic foci in the wall
- Weak rim enhancement
- Associated paranasal / Mastoid disease
- Concurrent pulmonary infection
Fig. 18: DWI PATTERNS IN FUNGAL LESIONS
Fig. 19: Weak ring enhancement --- Fungal abscess
2. CNS Mucormucosis
- Mucormycosis - molds belonging to the Mucor, Rhizopus, and Absidia genera.
- Inhalation of spores.
- Individuals with uncontrolled diabetes are at great risk.
- Rhinocerebral form
- Angioinvasive
Fig. 20: Rhinocerebral Mucormycosis
Fig. 21: Rhinocerebral Mucormycosis
References: https://radiopaedia.org/cases/rhinocerebral-mucormycosis?lang=us
Imaging Pearls:
1. Diabetics
2. T2 hypointense content in the sinuses
3. Nonenhancement / poor enhancement of mucosa / turbinates - BLACK TURBINATE SIGN
4. Contiguous Orbital/ intracranial extension and vascular invasion
DIMORPHIC FUNGI:
1. COCCIDIOMYCOSIS
- Coccidioides immitis
- CNS involvement-uncommon, usually secondary to hematogenous dissemination from lungs
- Patients usually present with
- headaches, lethargy, nausea, vomiting, visual changes
- mental status changes
- cranial nerve palsies
- clinical signs of meningeal irritation are often absent
Fig. 22: COCCIDIOMYCOSIS imaging spectrum
Fig. 23: COCCIDIOMYCOSIS
References: https://www.sciencedirect.com/science/article/pii/S2211753916300574#f0005
2. BLASTOMYCOSIS
- Blastomyces dermatitidis
- Clinical features: CNS manifestation is a rare complication but can be fatal.
- Head ache, focal neurological deficit, altered mental status, vision changes, and seizures.
- Meningitis
- Intracranial mass lesions
- Abscesses of the spinal cord or epidural space
Fig. 24: Blastomycosis
References: http://www.ijri.org/article.asp?issn=0971-3026;year=2016;volume=26;issue=1;spage=120;epage=125;aulast=Kochar
3. HISTOPLASMOSIS:
Clinical features:
- Seen is disseminated infection in immune compromised individual
- lowered level of consciousness
- headache
- cranial nerve deficiency
- seizures
- confusion
Imaging findings:
Fig. 25: Cerebral Histoplasmosis
References: Clin Neuroradiol (2014) 24:217–230 DOI 10.1007/s00062-014-0305-7