Ct brain shows mass prepontine cistern cpa meningioma. symptoms consistent with diagnosis. mri contrast show no lesion. symptoms persist! now what?

Very strange: Not certain what to make of the disparity between the CT scan and the MRI. In some cases, a lesion is so small that it is missed by the artifact created by the thickness of the MRI slices. I would ask your doctor if an MRI of the brainstem with "thin slices" might be reasonable to confirm/refute the CT--with and without contrast. Take care and stay healthy!