What does a CT scan of the brain without contrast show?

Some things. CT scan of brain without contrast shows basic anatomy of brain, gray white matter differentiation, ventricles, and physiologic calcifications.Ventricles enlarged/ hydrocephalus, mass effect with displacement of normal structures, some bleeding,abnormal calcifications in tumors or old subdural hematomas, fractures.CT with contrast adds enhancement of certain lesions not seen,hyper/hypo vascular.