Magnetic Resonance Imaging of Cerebral Aspergillosis: Imaging and Pathological Correlations

Abstract

Cerebral aspergillosis is associated with a significant morbidity and mortality rate. The imaging data present different patterns and no full consensus exists on typical imaging characteristics of the cerebral lesions. We reviewed MRI findings in 21 patients with cerebral aspergillosis and correlated them to the immune status of the patients and to neuropathological findings when tissue was available. The lesions were characterized by their number, topography, and MRI signal. Dissemination to the brain resulted from direct spread from paranasal sinuses in 8 patients, 6 of them being immunocompetent. Hematogenous dissemination was observed in 13 patients, all were immunosuppressed. In this later group we identified a total of 329 parenchymal abscesses involving the whole brain with a predilection for the corticomedullary junction. More than half the patients had a corpus callosum lesion. Hemorrhagic lesions accounted for 13% and contrast enhancement was observed in 61% of the lesions. Patients with hematogenous dissemination were younger (p = 0.003), had more intracranial lesions (p = 0.0004) and had a higher 12-week mortality rate (p = 0.046) than patients with direct spread from paranasal sinuses. Analysis of 12 aneurysms allowed us to highlight two distinct situations. In case of direct spread from the paranasal sinuses, aneurysms are saccular and located on the proximal artery portions, while the hematogenous dissemination in immunocompromised patients is more frequently associated with distal and fusiform aneurysms. MRI is the exam of choice for cerebral aspergillosis. Number and type of lesions are different according to the mode of dissemination of the infection.

Aspergillus nigerinfection in an immunosuppressed patient confined solely to the brain

“…Central nervous system aspergillosis has a poor prognosis with the variable mortality rate quoted in the literature being as high as 86% 4. Most patients who develop intracerebral aspergillosis are immunosuppressed, and in these patients, the primary source of the infection is most commonly the lungs4 following inhalation as the route of entry.…”

“…Most patients who develop intracerebral aspergillosis are immunosuppressed, and in these patients, the primary source of the infection is most commonly the lungs4 following inhalation as the route of entry. A. niger is an environmental organism found in soil, on plants and even in some food and condiments such as pepper.…”

“…A. niger is an environmental organism found in soil, on plants and even in some food and condiments such as pepper. Haematogenous spread to the brain is associated with poorer outcome than direct spread from sinusitis or craniofacial trauma 4. Mortality from cerebral aspergillosis in non-immunosuppressed patients is considerably lower—13% 5…”

“…There are case reports suggesting that newer antifungal drugs such as voriconazole can contribute to improved outcomes;9 however, lesions may take many months (up to 30 in one case) to resolve radiologically 4Learning points

 Mass lesions of the brain are not always tumours and comprehensive microbiology and histopathology investigations are required.

 Mortality is high among patients with intracerebral aspergillosis, and more so in the immunosuppressed, but there are reports of successful treatment with antifungal drugs.

 Cerebral Aspergillus infection may occur in the absence of primary infection in the sinuses or chest.

 MRI is the imaging modality of choice and should be repeated at regular intervals to assess the response to treatment, which may take many months.

…”

Invasive Aspergillosis in Transplant Recipients

“…Brain abscesses are common in HSCT recipients, while relatively rare in solid organ transplant (SOT) recipients [40,41]. CT and MRI are recommended in patients in whom cerebral aspergillosis is suspected [42]. Among all types of IA, brain aspergillosis has the worst prognosis, with mortality rate usually exceeding 90% (up to 100%), however early and proper treatment improves the prognosis in these patients and significantly increases their survival rates [19].…”