MRI of CNS Fungal Infections: Review of Aspergillosis to Histoplasmosis and Everything in Between

Abstract

Fungal infections of the central nervous system (CNS) represent a wide spectrum of diseases with some common magnetic resonance imaging (MRI) features. Risk factors include immunocompromise of any cause and living in endemic areas. CNS infection occurs through hematogenous spread, cerebrospinal fluid seeding, or direct extension. MRI features include heterogeneous or ring reduced diffusion and weak ring enhancement. Angioinvasive aspergillosis is characterized by multifocal hemorrhagic lesions with reduced diffusion. Cryptococcosis results in gelatinous pseudocyst formation in the basal ganglia. Mucormycosis is characterized by frontal lobe lesions with markedly reduced diffusion. Candidiasis is usually manifest by numerous microabscesses of less than 3 mm occurring at the corticomedullary junction, basal ganglia, or cerebellum. Coccidioidomycosis often results in meningitis with contrast enhancement of the basal cisterns. Blastomycosis and histoplasmosis are rare infections with parenchymal abscesses or meningitis. Recognizing the imaging features of CNS infections allows for early, aggressive treatment of these otherwise rapidly fatal infections.

Approach to the Solid Organ Transplant Patient with Suspected Fungal Infection

“…94 In advanced disease, cryptococcomas may be seen, particularly with C gattii infection. 94,95 Lumbar puncture (LP) should be performed when symptoms of meningitis are present.…”

“…94 In advanced disease, cryptococcomas may be seen, particularly with C gattii infection. 94,95 Lumbar puncture (LP) should be performed when symptoms of meningitis are present. It is of critical importance that an opening pressure be measured when performing the LP, because elevated intracranial pressure is associated with poor outcomes.…”

Ischaemic pituitary tumour apoplexy and concurrent meningitis: a diagnostic dilemma

“…Usually, the pituitary adenomas are isointense to hyperintense on T2-weighted image. The profound hypointense signal from the lesion on T2-weighted images in our case led us to initially suspect a fungal aetiology in our patient as the fungal hyphae containing paramagnetic elements like manganese, iron and magnesium return low signals on T2-weighted images 7. Diffusion weighted imaging further aids in supporting early diagnosis of pituitary tumour infarction showing diffusion restriction in the infarcted tissue.…”

Central nervous system blastomycosis presenting as a year-long chronic headache

“…Brain metastases frequently have a thicker ring enhancement, but typically have no reduced diffusion in the necrotic center. [5] Definitive diagnosis is established either by isolation of the fungus from a culture or direct visualization on the histological slides. Isolation from the CSF is uncommon.…”