Review of neuroimaging findings of intracranial angioinvasive fungal infections

With increasing use of broad-spectrum antibiotics, advances in organ and stem-cell transplant therapy, and the continued diabetes mellitus II epidemic, as well as other risk factors, reports of fungal infections of the CNS have been increasing. The most lethal subset is the angioinvasive fungal infection. Aspergillus fumigatus, Mucor, and Fusarium tend to affect immunocompromised individuals depending on their risk factors. Exserohilum rostratum and Cladophialaphora species tend to infect immunocompetent individuals. Early diagnosis and treatment are imperative for improved outcomes and reduced morbidity and mortality. Clinical presentation is often nonspecific, while neuroimaging can be helpful for accurate diagnosis. CT of the head and/or the maxillofacial structures is the primary imaging modality. Once the infection begins to proliferate, areas of vasogenic and cytotoxic edema, with regional mass effect and shift of the midline structures may be seen. These findings, however, are often nonspecific and may also be seen in underlying neoplasm, inflammatory processes, and other intracranial infections. Characteristic findings on T1, T2, diffusion-weighted imaging (DWI), and gradient echo sequences (GRE) may help to further narrow the differential diagnoses. We present a review of neuroimaging findings that will aid the neuroradiologist in distinguishing intracranial angioinvasive fungal infections and lead to improved patient outcomes.