BASICS OF CT SCAN NEUROIMAGING

Basic rule: Image orientation 2  By convention, the right side of the brain CT scan is on the left of the reader and it should be labelled as such!  Brain CT images are read as if you are viewing the patient from the feet thus their right side of the brain is to your left and vice vasa.  The anterior part of the head is at the top of the image. 9/26/2024 A.N. Malik, Department of Human Anatomy, JKUAT. The 3 basic densities/shades of grey 3  Isodense: same density as brain(sub-acute bleed)  Hyperdense: of higher density than the brain and appears whiter(bone and acute bleed).  Hypodense: of lower density than the brain and appears dark(CSF, air). 9/26/2024 A.N Malik, Department of Human Anatomy, JKUAT. Normal anatomy that can be confused with acute bleeds 4  Calcified pineal gland, choroid plexus and dentate nucleus. 9/26/2024 A.N Malik, Department of Human Anatomy, JKUAT. The density of blood changes with time 5 Note the change in the density of the blood from hyperdense (1 day) to hypodense with time (2 months). 9/26/2024 A.N Malik, Department of Human Anatomy, JKUAT. Gray and white matter of brain 6 White matter is located centrally and appears blacker than grey matter due to its relatively low density Clinical significance Pathological processes may increase or decrease the differentiation in density between grey and white matter 9/26/2024 A.N Malik, Department of Human Anatomy, JKUAT. Gray matter structures 7 Important grey matter structures visible on CT images of the brain include the cortex, insula, basal ganglia, and thalamus. 9/26/2024 A.N Malik, Department of Human Anatomy, JKUAT. Gray matter structures: cerebral cortex 8  The grey matter of the cerebral cortex is formed in folds called gyri  Note that the cortex appears whiter (denser) than the underlying white matter 9/26/2024 A.N Malik, Department of Human Anatomy, JKUAT. Gray matter structures: insula 9 The insula forms an inner surface of the cerebral cortex found deep to the Sylvian fissure Clinical significance Loss of definition of the insular cortex may be an early sign of an acute infarct involving the