BRAIN CT SCAN

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BRAIN CT SCAN

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Transcript of BRAIN CT SCAN

BRAIN CT SCAN

Anatomy &Physiology

BRAIN• is one of the largest and

most complex organ in the human body.

• The adult human brain weighs on average about 3 lbs. (1.5 kg)with a volume of around 1130 cubic centimeters (cm3) in women and 1260 cm3 in men

• Our brain gives us awareness of ourselves and of our environment, processing a constant stream of sensory data.

• It controls our muscle movements, the secretions of our glands, and even our breathing and internal temperature.

• Every creative thought, feeling, and plan is developed by our brain.

• The brain’s neurons record the memory of every event in our lives.

IT HAS THREE MAIN PARTS:

•Cerebrum•  the largest part of the mature brain. • It consists of two large masses, called

cerebral hemispheres, which are almost mirror images of each other.

•  The cerebrum is concerned with higher brain functions, interpreting sensory impulses and initiating muscle movements.

• It stores information and uses it to process reasoning.

• It also functions in determining intelligence and personality.

• The surface of the cerebrum has a folded appearance called the cortex.

• The cortex contains about 70% of the 100 billion nerve cells.

• The nerve cell bodies color the cortex grey-brown giving it its name – gray matter.

• Beneath the cortex are long connecting fibers between neurons, called axons, which make up the white matter.

 

•Cerebellum • a rounded structure located

behind the brain stem, to which it is linked by thick nerve tracts.

• It accounts for about 11% of the whole brain weight and appears similar to the cerebrum.

• It is concerned mainly with the maintenance of posture and balance and the coordination of movement.

•Brain Stem • Houses the midbrain

(mesencephalon), pons (part of the metencephalon), and medulla oblongata (myelencephalon).

• This is the posterior area of the brain that attaches to the spinal cord.

• It's here, at the brain stem, where information is sent back and forth between the cerebrum or cerebellum and the body.

• Cranial nerves 3-12 are located here as well as significant processing centers.

THE BRAIN IS ALSO DIVIDED INTO

SEVERAL LOBES:

Frontal lobe• Personality, behavior,

emotions,

• Judgment, planning, problem solving

• Speech: speaking and writing (Broca’s area)

• Body movement (motor strip)

• Intelligence, concentration, self awareness

Parietal lobe• Interprets language, words• Sense of touch, pain,

temperature (sensory strip)• Interprets signals from

vision, hearing, motor, sensory and memory

• Spatial and visual perception

Occipital lobe• Interprets vision (color,

light, movement)

Temporal lobe

• Understanding language (Wernicke’s area)

• Memory• Hearing• Sequencing and organization

DEEP STRUCTURES

• Hypothalamus - is located in the floor of the third ventricle and is the master control of the autonomic system. It plays a role in controlling behaviors such as hunger, thirst, sleep, and sexual response. It also regulates body temperature, blood pressure, emotions, and secretion of hormones.

• Pineal gland - is located behind the third ventricle. It helps regulate the body’s internal clock and circadian rhythms by secreting melatonin. It has some role in sexual development.

• Thalamus - serves as a relay station for almost all information that comes and goes to the cortex. It plays a role in pain sensation, attention, alertness and memory.

• Basal ganglia - includes the caudate, putamen and globus pallidus. These nuclei work with the cerebellum to coordinate fine motions, such as fingertip movements.

• Limbic system - is the center of our emotions, learning, and memory. Included in this system are the cingulate gyri, hypothalamus, amygdala (emotional reactions) and hippocampus (memory).

SKULL• The purpose of the bony skull is to protect the

brain from injury.

• The skull is formed from 8 bones that fuse together along suture lines.

• These bones include the frontal, parietal (2), temporal (2), sphenoid, occipital and ethmoid. The face is formed from 14 paired bones including the maxilla , zygoma, nasal, palatine, lacrimal, inferior nasal conchae, mandible, and vomer.  

INDICATIONS

CT scanning of the head is typically used to detect:

• bleeding, brain injury and skull fractures in patients with head injuries.

• bleeding caused by a ruptured or leaking aneurysm in a patient with a sudden severe headache.

• a blood clot or bleeding within the brain shortly after a patient exhibits symptoms of a stroke.

• a stroke, especially with a new technique called Perfusion CT.

• brain tumors.

• enlarged brain cavities (ventricles) in patients with hydrocephalus.

• diseases or malformations of the skull.

CT scanning is also performed to:• evaluate the extent of bone and soft tissue damage in patients with

facial trauma, and planning surgical reconstruction.

• diagnose diseases of the temporal bone on the side of the skull, which may be causing hearing problems.

• determine whether inflammation or other changes are present in the paranasal sinuses.

• plan radiation therapy for cancer of the brain or other tissues.

• guide the passage of a needle used to obtain a tissue sample (biopsy) from the brain.

• assess aneurysms or arteriovenous malformations through a technique called CT angiography.

CONTRAINDICATIONS

• CT scanning has no absolute contraindications.

• But due to the relatively high radiation dose involved in CT scans, it is important to avoid scanning patients who are pregnant. Radiation exposure to a fetus can cause developmental problems. Thus, CT should only be performed for pregnant patients in critical situations and only after discussion of the potential risks.

• Patients who have an allergy to the IV contrast media (IVCM) used in CT scans.

• Renal impairment may also prohibit your patient from having IVCM.

PRE-PROCEDURE PREPARATION

Before the CT scan, tell your doctor if you:

• Are or might be pregnant.

• Are allergic to any medicines, including iodine dyes.

• Have a heart condition, such as heart failure.

• Have diabetes or take metformin (Glucophage) for your diabetes. You may have to adjust your medicine for a day before and after the test.

• Have had kidney problems.

• Have asthma.

• Have a medical device, such as a pacemaker or an insulin pump.

• Become very nervous in small spaces. You need to lie still inside the CT scanner, so you may need a medicine (sedative) to help you relax.

• You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure.

• Metal objects, including jewelry, eyeglasses, dentures and hairpins, may affect the CT images and should be left at home or removed prior to your exam. You may also be asked to remove hearing aids and removable dental work. Women will be asked to remove bras containing metal underwire. You may be asked to remove any piercings, if possible.

• If your procedure involves the use of contrast dye, you will be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if something is not clear.

• Generally, there is no fasting requirement prior to a CT scan, unless a contrast dye is to be used. Your doctor will give you special instructions ahead of time if contrast is to be used and if you will need to withhold food and drink.

• Procedure with contrast:• Kidney function test (BUN and Creatinine)

must be done 72 hrs. before the procedure.• NPO (4 hours) before the procedure.• You may drink clear liquids up until the

time of your scan. Clear liquids include water, black coffee or tea, apple juice, clear soda or clear broth.

• Secure a consent form.

CONTRAST MEDIA• (Iopamiro/Ultravist)

>300 mg I/mL and 370 mg I/mL

DURING THE PROCEDURE

• You will lie on a scan table that slides into a large, circular opening of the scanning machine. Your head may be immobilized to prevent movement during the procedure.

• The technologist will be in another room where the scanner controls are located. However, you will be in constant sight of the technologist through a window. Speakers inside the scanner will enable the technologist to communicate with and hear you. You may have a call button so that you can let the technologist know if you have any problems during the procedure. The technologist will be watching you at all times and will be in constant communication.

• As the scanner begins to rotate around you, X-rays will pass through the body for short amounts of time. You will hear clicking sounds, which are normal.

• The X-rays absorbed by the body's tissues will be detected by the scanner and transmitted to the computer. The computer will transform the information into an image to be interpreted by the radiologist.

• It will be very important for you to remain very still during the procedure. You may be asked to hold your breath at various times during the procedure.

• If contrast dye is used for your procedure, you will be removed from the scanner after the first set of scans has been completed. A second set of scans will be taken after the contrast dye has been administered.

• If contrast dye is used for your procedure, you may feel some effects when the dye is injected into the IV line. These effects include a flushing sensation, a salty or metallic taste in the mouth, a brief headache, or nausea and/or vomiting. These effects usually last for a few moments.

• You should notify the technologist if you feel any breathing difficulties, sweating, numbness, or heart palpitations.

• When the procedure has been completed, you will be removed from the scanner.

• If an IV line was inserted for contrast administration, the line will be removed.

• You may be asked to wait for a short period of time while the radiologist examines the scans to make sure they are clear.

POST PROCEDURE

• If contrast dye was used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast dye, such as itching, swelling, rash, or difficulty breathing. Notify the radiologist or your doctor if you experience any of these symptoms.

• If you notice any pain, redness, and/or swelling at the IV site after you return home following your procedure, you should notify your doctor as this could indicate an infection or other type of reaction.

• Otherwise, there is no special type of care required after a CT scan of the brain. You may resume your usual diet and activities unless your doctor advises you differently.

• Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

• If you are a diabetic who takes any medication that contains metformin, you must have a blood test to check your kidney function before you can start taking metformin again. Call your doctor for the results of the blood test and for instructions about resuming metformin. 

PROTOCOLS

ROUTINE ADULT HEAD (BRAIN)

PATIENT POSITIONING: • • Patient should be supine, head first into the gantry, with the head in the

head-holder whenever possible.

• • Center the table height such that the external auditory meatus (EAM) is at the center of the gantry.

• • To reduce or avoid ocular lens exposure, the scan angle should be parallel to a line created by the supraorbital ridge and the inner table of the posterior margin of the foramen magnum.

• This may be accomplished by either tilting the patient’s chin toward the chest (“tucked” position) or tilting the gantry.

• While there may be some situations where this is not possible due to scanner or patient positioning limitations, it is considered good practice to perform one or both of these maneuvers whenever possible.

• SCAN RANGE: Top of C1 lamina through top of calvarium.

CONTRAST: • Oral: None.

• Injected: Some indications require injection of intravenous or intrathecal contrast media during imaging

• of the brain.

• Intravenous contrast administration should be performed as directed by the supervising radiologist

• using appropriate injection protocols and in accordance with the ACR Practice Guideline for the Use of Intravascular Contrast Media. A typical amount would be 100 cc at 300 mg/cc strength, injected at 1 cc/sec. A delay of 4 minutes between contrast injection and the start of scanning is typical.

AXIAL VERSUS HELICAL SCAN MODE (both are provided in the following sample protocols):

• There are advantages and disadvantages to using either axial or helical scans for routine head CT exams. The decision as to whether to use axial or helical should be influenced by the specific patient indication, scanner capabilities, and image quality requirements.

• Users of this document should consider the information in the following table and consult with both the manufacturer and a

• medical physicist to assist in determining which mode to use.

PITUITARY AND SELLA TURCICA

SCOUT: LATERALLANDMARK: OMLSLICE PLANE: CORONAL & AXIALI.V. CONTRAST: 100-140 MLBREATH HOLD: NONESLICE THICKNESS: 1-1.5 mmFILMING: BONE & SOFT TISSUE

DFOV 12

PATHOLOGY

PATHOLOGY

EPIDURAL HEMATOMA• An epidural hematoma is

usually associated with a skull fracture. It often occurs when an impact fractures the calvarium. The fractured bone lacerates a dural artery or a venous sinus. The blood from the ruptured vessel collects between the skull and dura.

Biconvex (lenticellular) epidural hematoma (arrowheads),

deep to the parietal skull fracture (arrow).

SUBARACHNOID HEMORRHAGE• A subarachnoid hemorrhage occurs

with injury of small arteries or veins on the surface of the brain. The ruptured vessel bleeds into the space between the pia and arachnoid matter. The most common cause of subarachnoid hemorrhage is trauma. In the absence of significant trauma, the most common cause of subarachnoid hemorrhage is the rupture of a cerebral aneurysm.

High density blood (arrowheads) fills the sulci over the

right cerebral convexity in this subarachnoid hemorrhage.

SUBDURAL HEMATOMA

• is a type of hematoma, usually associated with traumatic brain injury.

•  Blood gathers with the outermost meninges layer, between the dura mater, which adheres to the skull, and the arachnoid mater, which envelops the brain. High density, crescent shaped

hematoma (arrowheads) overlying the right cerebral

hemisphere. Note the shift of the normally midline septum

pellucidum due to the mass effect arrow.

HEMORRHAGIC STROKE

• are due to rupture of a cerebral blood vessel that causes bleeding into or around the brain

Hemorrhage in the cerebellum (arrow).

HYDROCEPHALUS

• Hydrocephalus, a problem with the ratio of production of CSF to its re-absorbtion, is most frequent in children.

INTRACRANIAL TUMOR

• Intracranial tumors generally present with a focal neurological deficit, seizure, or headache.

Multiple enhancing masses located at the grey-white junction zones.

MENINGIOMA• Meningiomas are the

most common extra-axial neoplasm of the brain. Middle-aged women are most frequently affected. Twenty percent of meningiomas calcify. On CT, meningiomas are usually isointense to gray matter.

Axial, post contrast CT demonstrating broad based enhancing extra-axial mass.

CT IMAGES

A. OrbitB. Sphenoid SinusC. Temporal LobeD. External Auditory CanalE. Mastoid Air CellsF. Cerebellar Hemisphere

A. Frontal LobeB. Frontal Bone (Superior Surface of Orbital Part)C. Dorsum SellaeD. Basilar ArteryE. Temporal LobeF. Mastoid Air CellsG. Cerebellar Hemisphere

A. Frontal LobeB. Sylvian FissureC. Temporal LobeD. Suprasellar CisternE. MidbrainF. Fourth VentricleG. Cerebellar Hemisphere

A. Falx CerebriB. Frontal LobeC. Anterior Horn of Lateral VentricleD. Third VentricleE. Quadrigeminal Plate CisternF. Cerebellum

THE END Reported by: Joan C. Vargas