A 32-year-old man comes to the office with a history of fever and confusion for ten days. He also complains of headache associated with it. He was diagnosed with HIV 2 years ago and is on retroviral therapy. He has a history of poor compliance with the medications. Temperature is 38.2 C (100.8 F), blood pressure 112/72 mm of Hg, and pulse is 103/min. On examination, cervical lymphadenopathy is present. Cardiopulmonary examination is unremarkable. Neurological examination shows right-sided hemiparesis. CD4 count is 78/mm3. MRI of the head reveals multiple ring-enhancing lesions shown in the exhibit below.