Plain MRI brain (IV contrast (gadolinium) was not given due to our limited experience regarding its safe use in pregnancy).
The scan reveals a focal ill-defined heterogeneous mass lesion measuring 3 x 4 x 7 cm in the anterior corpus callosum with extension on either side into the white matter of both frontal lobes (butterfly lesion). The mass appears hypointense on T1 and hyperintense on T2 and FLAIR images.
Multiple tiny haemorrhagic foci are visible in the mass on SWI. The mass exhibits mild diffusion restriction. Moderate vasogenic oedema is observed around the lesion in both frontal lobes, with extension into the anterior limbs of both internal capsules and into the external capsule-claustrum regions.
Mass effect is evident over the frontal horns of both lateral ventricles; however, no midline shift or hydrocephalus is detected. The remaining brain parenchyma appears normal. Based on these MRI features, potential diagnoses include high-grade glioma, primary CNS lymphoma, tumefactive demyelination, or an atypical infection like toxoplasmosis.