CT - Brain Examination Submitted by: Felemban 1
CT - Brain Examination The clinical indication of CT brain are: a) Chronic cases (e.g. headache - tumor - abscess) b) ER cases (e.g. trauma - RTA - child fallen - stroke ) The (plan scan) must be parallel to the OML & and the FOV must include all the skull (from the base to the vertex) The (slice thickness) is around: a) O,3 mm (Pediatric) - 0,5 (adult) mm for (Posterior Fossa) to prevent Artifact b) 0,8-0,10 mm for leftover brain parts The standard views of: a) Brain: axial view b) PNS: axial + coronal views, with applying of (PNS + soft tissue) windows c) Petrous bones: axial + coronal views, with applying of (bone + soft tissue) windows CM injection is usually in the case of (hypodense area). The additional enhancement of CM can allow us to know the number (single or multiple) and the nature (mass - tumor - TB - abscess - inflammation - edema) CM also administered in (Orbits - Sella Turcica) scans ER (trauma) patient has only 2 chances: a) Fracture: associated with Hemorrhage (hyperdense area) & Contusion of brain tissue b) Stroke: associated with Hemorrhage & Infarction (hypodense area) No need for CM injection in all these chances With ER (trauma) patient, do: a) Bone window b) Soft tissue window 2
You must keep patient immobilization; especially with sedated CT patient (usually it is Incomplete Sedation to avoid CNS damage). Motion artifact can cover Lesions Density measurement: it is measuring of the attenuation (HN) of a specific part (ROI), to know it's nature (fluid - calcification - soft tissue - high protein area) Bad Patient Centralizer in the table, can cause unsymmetrical appearance of bilateral organs (e.g. eyeballs - orbits - petrous bones) To differentiate between (tumor) & (infarction), Tumor always associated with Mass effect (Displacement of parts around the tumor) + rounding Edema To differentiate between (Hemorrhage) & (tumor), Hemorrhage always appears hyperdense (in C- study). During the time, Hyperdense hemorrhage become (Hypodense) in the follow study To know if the study is with or without CM, look to the rounding Vessels; if it is visible & hyperdense CM study Ventricles dilatation: it is due to accumulation of CSF in the ventricles that is may caused by: a) Hemorrhage or Infection: that cause adhesion of CSF drainage way b) Congenital anomalous with Pediatric Rhinorrhea: discharge of cerebrospinal fluid through the nose, usually due to skull fracture that causes a communication between CSF space & Nasal cavity. It is diagnosed by: CT - myelography CT - myelography: a. A contrast agent is injected through a needle into the space around the spinal cord at the level of (L4 - L5) to prevent spinal cord damage b. Immediately after CM injection, patient transfer to CT unit & do CT-Brain (axial & coronal views) c. The injected CM will change the appearance of the CSF that placed around Spinal cord & Brain, from appearance of (Hypodense) to (Hyperdense) d. The purpose of CT - myelography is to found the nature & location of the (Defect) that cause the presence of CSF in Ethmoidal sinuses & Nasal cavity 3
Image comments: 1) Scout view: 0,8-0,10 mm for leftover brain parts (Plan scan) is parallel to the OML FOV already include all the skull (from the base to the vertex) O,5 mm for (Posterior Fossa) 2) Anatomy of Posterior Fossa + Orbital Atrophy: Orbital Atrophy Brainstem Petrous bones Lt. Cerebellum hemisphere 4th Ventricle Occipital Bone 4
3) Brain Lobes (in the lower cuts): Frontal Lobe Temporal Lobe Lateral Ventricle 3rd Ventricle Occipital Lobe 4) Brain Lobes (in the middle cuts): Frontal Lobe Parietal Lobe Body of Lateral Ventricle Occipital Lobe 5
5) Brain Lobes (in the upper cuts): Parietal Lobe 6) Bone window: 6
7) Hypodense Lesion (Infarction): Hypodense Lesion without mass effect (Infarction) 8) Choroid plexus calcification + Infarction: Hypodense Lesion (Infarction) Choroid plexus calcification 7
9) Lt. Cerebellar Hemorrhage + Bad Patient Centralizer: Unsymmetrical appearance of Petrous bones Hyperdense Lesion in Lt. Cerebellum hemisphere (Hemorrhage) 10) Hemorrhage: Hyperdense Lesion in Lt. Temporal lobe (Hemorrhage) 8
11) Brain atrophy + Ventricles dilatation + Shunt tube : Ventricles dilatation Brain Atrophy Shunt tube 12) Brain atrophy + Ventricles dilatation + Shunt : Brain Atrophy Ventricles dilatation Shunt tube 9