Specific Imaging Findings

The involvement of the brain in congenital toxoplasmosis may range from mild to severe. Subtle to coarse and chunky calcifications without periventricular predilection are commonly present and randomly distributed. There is destruction of the brain parenchyma with hydrocephalus and atrophy in severe cases. Ventriculomegaly is due to aqueductal atresia from ependymal involvement and shows a somewhat typical posterior predominance. In addition to calcifications, CT may show focal hypodense areas in the white matter. US demonstrates calcifications and cystic lesions in the periventricular white matter. Lenticulo-striate vasculopathy (LSV) with hyperechogenic linear branching structures corresponding to vasculature is a nonspecific finding, suggesting an infectious process. Ultrasound and CT have comparable sensitivity for intracranial calcifications of congenital toxoplasmosis. MR findings include periventricular foci of bright T1 signal due to calcification and gliosis. T2-weighted images demonstrate cystic white matter lesions and abnormal white matter hyperintensity due to gliosis, while the calcifications are dark. Recent cystic changes may be bright on DWI and show decreased diffusivity from cytotoxic edema. MR spectroscopy is not specific, but may reveal a prominent lactate peak. In contrast to CMV, cortical malformations such as polymicrogyria are infrequent.

Pertinent Clinical Information

Congenital toxoplasmosis is caused by transplacental contamination of the fetus following maternal primary infection. It is substantially less frequent than cytomegalovirus (CMV) infection; however, it is more commonly symptomatic. Education and serological screening of pregnant women are the only currently available strategies for the prevention, diagnosis, and treatment since the infection usually goes unrecognized in pregnant women.