Diffusion-weighted imaging in brain aspergillosis

Brain aspergillosis is a rare pathology, occurring mainly in immunocompromised patients, responsible for multiple cerebral septic infarctions. Some researchers have described magnetic resonance (MR)findings in cerebral invasive aspergillosis, but diffusion-weighted imaging (DWI) has rarely been reported, especially in typical nonenhancing lesions, while it may be helpful for early differential diagnosis and may allow earlier antifungal treatment. We describe three cases of patients presenting brain aspergillosis, with MR imaging including diffusion-weighted sequences and apparent diffusion coefficient (ADC) cartography. The three patients described in this study presented a total of 23 circular lesions, and one patient presented an infarction area in the territory of the right middle cerebral artery. Lesions were ring-enhancing for one patient, and presented no enhancement for the other two. Eleven lesions were very bright on DWI, with reduced ADC values. Twelve lesions, either enhancing or not enhancing, presented a 'target-like' aspect with central and peripheral hypointense areas on DWI, corresponding to higher ADC value areas, and intermediate marked hypersignal on DWI. This typical aspect of aspergillosis lesions on DWI may allow early diagnosis and treatment of cerebral aspergillosis, and is helpful for differentiating aspergillosis lesions from other infectious or malignant lesions affecting immunocompromised patients.