Which imaging modality is used to evaluate suspected cerebral toxoplasmosis?

Which imaging modality is used to evaluate suspected cerebral toxoplasmosis?

• A. Spinal MRI
• B. Chest X-ray
• C. Abdominal ultrasound
• D. Head CT/MRI showing ring-enhancing lesions

Answer: (D)

Imaging the brain with contrast is the key study for suspected cerebral toxoplasmosis. Toxoplasma encephalitis typically produces focal necrotizing lesions that disrupt the blood-brain barrier, which shows up as ring-enhancing lesions on contrast-enhanced CT or MRI. In immunocompromised patients, especially with AIDS and low CD4 counts, these multiple ring-enhancing lesions are a classic finding, often located in the basal ganglia or at the corticomedullary junction. A head CT or MRI with contrast is used because it directly evaluates the brain and can reveal these characteristic lesions, as opposed to imaging modalities like spinal MRI, chest X-ray, or abdominal ultrasound, which do not assess the brain for this condition. MRI with gadolinium is more sensitive for detecting smaller lesions and better defining extent, while CT is often used first in urgent settings.

Imaging the brain with contrast is the key study for suspected cerebral toxoplasmosis. Toxoplasma encephalitis typically produces focal necrotizing lesions that disrupt the blood-brain barrier, which shows up as ring-enhancing lesions on contrast-enhanced CT or MRI. In immunocompromised patients, especially with AIDS and low CD4 counts, these multiple ring-enhancing lesions are a classic finding, often located in the basal ganglia or at the corticomedullary junction.

A head CT or MRI with contrast is used because it directly evaluates the brain and can reveal these characteristic lesions, as opposed to imaging modalities like spinal MRI, chest X-ray, or abdominal ultrasound, which do not assess the brain for this condition. MRI with gadolinium is more sensitive for detecting smaller lesions and better defining extent, while CT is often used first in urgent settings.