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N806 and ct head N806 and ct head Presentation Transcript

  •  CT radiology CT anatomy Glossary of terms Clinical indications Systematic interpretation Head trauma Stroke Tumor
  •  Brain mets/tumor Infection/abscess Nodes/masses Pulmonary embolism Abdomen/pelvis
  • Patient A Patient B
  • Note how the subdural bleed (left side) has compressed the ipsilateral ventricle resulting in a compensetory expansion of the contralateral ventricle.Used with permission by the CRASH Trials with credit to Mr. J. Wasserberg and Mr. B. Mitchell
  •  Terms beginning with A – M Terms beginning with N - Z
  •  Amnesia  Cistern(s)  Corpus callosum Arachnoid granulations  Dorsum Sellae Arachnoid membrane  Dura mater Basal ganglia  Falx cerebri Basilar Artery  Globus pallidus (see basal ganglia) Calvarium  Gyrus Caudate (see basal  Herniation ganglia)  Insula/insullar ribbon  Internal capsule Cerebellum  Lentiform nuclei (see basal Cerebral cortex ganglia) Choroid plexus  Medulla  Midbrain Circle of Willis
  •  Process where by increased intracranial pressure forces brain parenchyma through a fixed opening. Clinical scenarios:  Transtentorial herniation (aka “uncal” herniation) ▪ Medial temporal lobes (uncus) and brainstem are forced through the tentorium ▪ Symptoms include headache, decreased consciousness, pupillary dilation and may progress to extensor posturing and death  Cerebellar herniation (rare) ▪ Cerebellar tonsils are “pushed” into the foramen magnum ▪ Similar symptoms as transtentorial herniation
  •  The cerebrum is the largest part of the brain and is responsible for thought and abstraction. The cerebrum is divided in four “lobes”. Some authors include the insula as the fifth “lobe” of the cerebrum The outer layer of the cerebrum (cortex) is gray matter (lacks myelin)
  •  Anterograde amnesia = Loss of memory for an event or events immediately following a head injury. Retrograde amnesia = Loss of memory for an event or events preceeding a head injury.
  •  From the Greek Arachnoid granulations arakhnoeid’s, (cobweblike) Villous projects of the pia-arachnoid membrane whose function is to absorb CSF and return it to the venous circulation via the superior saggital sinus.
  •  A thin membrane adherent to the dura mater. The arachnoid membrane is the middle layer of the three meningial layers (dura mater, arachnoid membrane, and pia mater) that surround the brain and spinal cord.
  •  The basasl ganglia consists of three gray matter structures (caudate, putamen, and globus pallidus) deep within cerebral hemispheres  Lentiform nuclei = putamen and globus pallidus Functions as motor relay stations Pathology in the basal ganglia results in purposeless movements (Parkinson’s disease)
  •  The basilar artery provides blood to the posterior aspect of the Circle of Willis and is formed from the paired vertebral arteries. Supplies blood to the pons, cerebellum, and posterior cerebrum.
  •  The circle of Willis is a term used to describe the arterial supply for the brain. The circle is derived from the two internal carotid arteries as well as the basilar artery, the latter being the continuation of the two vertebral arteries.
  • Vertebral arteries
  • Vertebral arteries
  •  The bony “roof” of the skull; also know as the “skull cap”.
  •  The cerebellum is that portion of the brain that is involved with coordination of voluntary movement, balance, and muscle tone.
  •  Connects the brainstem with the forebrain and is involved in the control of sensory processing
  •  Ventricluar tissue (ependyma) that produces cerebral spinal fluid (CSF).
  •  From Latin (“box”). A well defined collection of CSF within the subarachnoid space (located between the pia and arachnoid membranes). Several cisterns are generally described and two are of importance in the CT head:  Suprasellar - (Star-shaped) Location of the Circle of Willis  Quadrigeminal - W-shaped at top of midbrain
  •  The corpus callosum is the structure that connects the left and right cerebral hemispheres.
  •  The dorsum sellae is the square shaped part of the sphenoid bone that forms the posterior boundary of the pitutary fossa.
  • Dorsum sellae
  •  Latin (“hard Dura Mater Epidural hematoma Brain mother”) The outer, fibrous portion of the meninges.
  •  A reflexion of the dura mater located between the cerebral hemispheres. Function is to provide support to the cerebral hemispheres.
  •  The rounded, elevated convolutions on the surfaces of the cerebral hemispheres.
  •  The insula is one of the five cerebral cortices (frontal, parietal, temporal, occipital, insular) and is located deep to the frontal, parietal, and temporal lobes. Function is to integrate autonomic functions.
  •  Collection of axons that carry sensory information to the cortex and motor information to the cord. The internal capsule is very sensitive to stroke
  •  Aka “medulla oblongata” Located in the brain stem and sits below the pons and in front of the cerebellum. Functions to help control autonomic function, especially heart rate and breathing.
  •  Includes the midbrain, pons, and medulla. Major function is survival (breathing, digestion, heart rate, blood pressure) and for arousal (being awake and alert).
  •  Occipital lobe  Septum pellucidum Parenchyma  Sulcus Parietal lobe  Suture(s) Pineal gland  Temporal lobe Pneumocephalus  Tentorium cerebelli Pons  Thalamus Posterior fossa  Uncus Putamen (see globus  Ventricle(s) pallidus) Sagittal sinus
  •  Pneumocephalus (see red arrow) is the presence of air (or gas) within the cranial cavity and is usually associated with a basilar skull fracture
  •  The sutures are fibrous connections between bones of the skull Sutures allow for some flexibility of the cranium Fontanelles (aka “soft spots”) are unfused areas where sutures meet Sutures ossify at various times throughout life
  •  The pons sits between the brainstem and medulla Controls rate and depth of breathing Relays impulse from medulla to cerebrum Clinical pathology results in:  Bilateral, fixed, pinpoint pupils (comatose patient)  Cheyne-Stokes breathing ▪ Hyperventialtion followed by apnea
  •  The uncus is the medial (innermost) portion of the temporal lobe Under high intracranial pressure (ICP) the uncus can be involved in a transtentorial herniation syndrome  ICP pushes the uncus through the tentorium cerebelli which results in compression of the brainstem
  • 1. The brain squeezes under the falx cerebri in cingulate herniation2. The brainstem herniates caudally3. The uncus and the hippocampal gyrus herniate into the tentorial notch4. The cerebellar tonsils herniate through the foramen magnum in tonsillar herniation
  •  The ventricles are CSF-containing cavities Provides a protective cushion (buoys the brain) CSF produced in roof of ventricles (choroid plexes) Circulation of CSF through ventricles and around the brain (subarachnoid space) and cord (central canal) with reabsorption in arachnoid villi
  •  The thalamus is the central relay station for sensory fibers (except olfactory) Cerebral cortex communicates with thalamus Responsible for primitive emotional responses  Fear  Pleasant vs. unpleasant stimuli
  •  The temporal lobes are one of the five cortical lobes The temporal lobes are responsible for hearing, speech, and some emotional and memory functions
  •  Lain – “groove” or “trench” Pleural – “sulci” (sul-sigh) The small cracks or dimples on the surface of the brain
  •  The septum pellucidum is a thin midline structural membrane The septum runs vertically between the lateral ventricles as well as inferiorly from the corpus callosum
  •  Aka “superior sagittal sinus” Large collection of venous blood above and behind the brain Attached to the falx cerebri Receives CSF from the arachnoid granulations
  •  The posterior fossa is an area within the intracranial cavity bound by the tentorium cerebelli above and foramen magnum below The posterior fossa contains the cerebellum and brainstem structures
  •  Aka “pineal body” The pineal glad is an endocrine gland that produces melatonin and is important in sleep-wake cycles
  •  The parietal lobe is the cortical lobe responsible for sensation (cutaneous and muscular) Responsible for integration of thoughts and feelings
  •  The functional tissue(s) (key elements) of an organ
  •  The occipital lobe is the cortical lobe responsible for vision Integration areas for visual images with sensory experiences. Dura matter (tentorium cerebelli) separates the occipital lobe from the cerebellum
  •  The putamen is part of the basasl ganglia The basals ganglia consists of three gray matter structures (caudate, putamen, and globus pallidus) deep within cerebral hemispheres  Lentiform nuclei = putamen and globus pallidus Functions as motor relay stations Pathology in the basal ganglia results in purposeless movements (Parkinson’s disease)
  •  CT head is currently the procedure of choice for evaluation of suspected stroke Stokes are either hemorrhagic (minority) or nonhemorrhagic (vast majority of cases) Nonhemorrhagic strokes = “ischemic” strokes  The latter, if diagnosed quickly, can (potentially) be treated with thrombolytic agents  The CT can reliably serve to rule out intracranial hemorrhage The CT is examined for evidence of vascular occlusion (clots), edema, and hemorrhage
  •  General considerations  Stroke anatomy Hemorrhagic CVA Nonhemorrhagic (ischemic) CVA
  •  Cerebral vascular supply (Circle of Willis) The motor and sensory Homunculus Arterial supply and brain function
  •  General considerations CT findings
  •  General considerations CT scan of hemorrhagic CVAs  Basal ganglia location  Cerebellar location  Gross pathology of cortical CVA
  • Hypertensive hemorrhagein the basil ganglia
  •  Hemorrhagic strokes are due to rupture of a cerebral blood vessel  Bleeding can occur into or around the brain  Blood may extend into the ventricular system Hemorrhagic strokes account for 16% of all strokes  Hypertensive hemorrhage accounts for approximately 70-90% of non-traumatic primary intracerebral hemorrhages
  •  Etiologies include thrombus, embolism, or hypoperfusion Ischemic brain tissue becomes edematous Edematous tissue will appear hypodense on noncontrast CT  Hypodensity begins as early as 1h post-CVA ▪ Earliest sign of CVA is loss of gray-white differentiation (the "insular ribbon" sign)  Hypodensity is completely manifest by 12-24 hours post- CVA
  •  Obscuration of the lentiform nuclei Hypoattenuation of the insular ribbon Sulcal effacement and cortical hypodensity Hyperdense vessel signs
  •  Lentiform nuclei = globbus palladus and putamen (parts of the basal ganglia) Edema from ischemia produces hypodenity of basasl ganglia structures within hours of event Red arrows denotes hypodensity of the basal ganglia structures (compare to opposite side)
  •  An occluded vessel (thrombus) may appear ”dark” on CT The red arrow denotes a dense basilar artery
  •  Red arrows point to hypodensity and sulcal effacement. Note the generalized edematous appearance of the tissues within the middle cerebral artery distribution
  •  Moderate - severe head trauma is an indication for a CT head scan Some controversy exists as to when a CT should be obtained for a “minor” head injury in adults:  Canadian CT recommendations  New Orleans Criteria For infants and children:  Considerations  General recommendations
  •  Things to Think About Interpretation Mnemonics Order of Evaluation (basic)  Bone windows  Blood (intracranial hemorrhage)  Brain parenchyma  Ventricles  Cisterns
  •  Introduction CT considerations and clinical importance Diagrams  Ventricular anatomy  CSF circulation CT images  Normal lateral ventricles  Normal third ventricle  Ventriculomegaly  Ventricular compression and enlargement
  •  Brain parenchyma = brain “tissue” The brain parenchyma is symmetrical Gray and white matter should be well defined  Edema results in poor delineation Midline structures (falx cerebri, third and fourth ventricles) should not be deviated  Deviated midline structures is evidence of mass effect = edema, bleeding, tumor Check the parenchyma for evidence of blood
  •  General considerations CT images  Normal midline structures  Midline shift  Cerebral edema
  •  Notice the sharp difference between the large hypodense edematous (red arrows) tissue and the remaining “normal” cortical tissue
  • Used with permission by the CRASH Trials with credit to Mr. J. Wasserberg and Mr. B. Mitchell
  •  Noncontrast study is standard  A contrast study will be so designated on the CT images Most scanners are now “ultrafast” and can perform a head CT in less than one minute Scan spans from the base of the occiput to the top of the vertex in 5-mm increments Three sets of data are derived from the primary scan:  Bone windows (fractures)  Tissue windows (gray/white matter density)  Subdural windows (brain bleed)
  •  Evaluation of head trauma ▪ Cerebral hemorrhages ▪ Skull fracture Suspected cerebrovascular accident (CVA) Suspected brain tumor Hydrocephalus
  •  Clinical syndromes CT indications versus MRI
  •  Progressive headaches associated with:  Vomiting (especially early AM)  Behavior changes
  • CT MRI Fast, easy, available, and  Slower and more expensive relatively cheap  Soft tissue and joints Study of choice for  Spine and spinal cord  Posterior fossa and orbits suspected brain bleed  Better for CNS Generally good for solid developmental organs and bleeds applications Good study for chest,  Can’t be used with certain abdomen, and pelvis pacemakers and (metal) pathology implants Radiation exposure
  •  Relative Density (Attenuation) Radiation Exposure CT protocols  Noncontrast (“standard”)  With contrast (“enhanced”)
  •  IV contrast – general considerations Clinical indications Contraindications
  •  I.V. contrast is given to differentiate blood vessels from soft tissue and organs  Blood and falx appear white with contrast Original ionic contrast agents have largely been replaced with nonionic agents (fewer reactions)  Iodine reactions were actually responses to the carrier molecule of the contrast rather than iodine Risk related to IV contrast:  Anaphylaxis ~ 1:10,000  Death ~ 1:40,000 – 100,000 NPO X 4 hours before administration of IV contrast  Depends on urgency of exam
  •  Quick Easy Available Inexpensive (fairly) Standard of care for closed head injury evaluation  Shows bony calvarium well ▪ Bone windows can show fractures easily
  • “The five B’s” “Blood Can Be Very Bad” Blood  Blood = blood Brain  Can = cisterns Bone  Be = brain Balloons (ventricles)  Very = ventricles Boxes (cisterns)  Bad = bone
  •  Just like a standard X-ray, the CT shows dense objects (bone) as white and less dense objects (air) as black. The concept of relative density is known as attenuation and is measured in Hounsfield Units (HU)
  • Structure Hounsfield Units Bone + 1,000 Blood + 50-100 Gray matter + 32 - 46 White matter + 22 - 36 CSF + 4 - 10 Water 0 Air -1,000 Clincal caveat: The radioglogist can place the computer cursor on any part of the CT image and determine the exact HU density – a real time way to differentiate blood from abscess from CSF, etc.
  •  The CT scan is a sophisticated x-ray that literally takes a continuous x-ray as it moves around the patient (tomogram) The X-ray source and detector unit are situated opposite of each other  360 degree movement around the patient  Very thin x-ray beams are utilized The CT computer integrates the assembled x- ray information and produces a “relative density” map that we view as a gray-scale image.
  • Type of Exposure Dosage (mSv) Background radiation 3 mSv/year CXR 0.1 mSv CT head 2 mSv CT chest 8 mSv CT abdomen and pelvis 20mSv Caveat: A CT head is the equivalent of 20 CXRs, while a CT abdomen & pelvis equals 200 CXRs! Yikes!
  •  General considerations CT Description CT images  Normal supracellar cistern  Normal quadrigeminal cistern  Compression of supracellar cistern (early)
  • Notice how the right uncus is pushing into the supracellar cistern.Dx: Early uncal herniation from increased intracranial pressure
  •  From Latin (“box”) Collections of CSF within the subarachnoid space (between the pia and arachnoid membranes) Cistern pathology is usually seen on CT as compression or presence of blood  Compression ▪ Increased intracranial pressure (herniation symndrome) ▪ Mass effect (tumor)
  •  Several cisterns are described but two are of importance in the CT head:  Supracellar cistern ▪ Star-shaped (“super star”) ▪ Location = Circle of Willis  Quadrigeminal cistern ▪ W-shaped (looks like a baby’s bottom) ▪ Location = Level of tentorium cerebelli
  • A. Falx CerebriB. Frontal LobeC. Anterior Horn of Lateral VentricleD. Third VentricleE. Quadrigemina CisternF. Cerebellum Can you visualize the “baby’s bottom”?
  •  Notice how the falx is deviated (white arrow) due to a space filling lesion (red outline)
  •  Developed from a series of patients ( > 16 years-of-age) presenting with minor head injury (defined as GCS score of 13-15 after loss of consciousness, definite amnesia, or witnessed disorientation from trauma) Clinical criteria consist of five high-risk and two moderate-risk factors.
  • Obtain CT Head if patient has > one the following seven: GCS score lower than 15 two hours after injury Suspected open or depressed skull fracture Any sign of basal skull fracture Two or more episodes of vomiting Age 65 years or older Retrograde amnesia > 30 minutes Dangerous mechanism  Motor vehicle involved  Fall from a height of at least three ft or five stairs
  •  CT is needed if the patient > one of the following:  Headache  Vomiting  Age older than 60 years  Drug or alcohol intoxication  Persistent anterograde amnesia (deficits in short-term memory)  Visible trauma above the clavicle  Seizure *Applicable for adults with a normal Glasgow Coma Scale score of 15 and blunt head trauma that occurred within the previous 24 hours that caused loss of consciousness, definite amnesia, or witnessed disorientation.
  •  Evaluate the significance of the injury by physical findings AND mechanism of injury Kids have heavy heads and weak necks  Younger children are less likely to be symptomatic Signs of significant head injury can be subtle (persistent irritability) Scalp hematomas in infants and toddlers suggest significant injury
  •  All moderate and severe head trauma Any loss of consciousness Age under 3 months  Skull fracture (intracranial injury in 15-30%)  Scalp hematoma predicts fracture (>80% sensitivity) Depressed mental status Focal neurologic deficits Bulging fontanelle Persistent irritability after head injury Seizure following head injury Recurrent vomiting after injury
  •  Bone windows for fractures Brain tissue  Hemorrhage or masses  Symmetry  Midline shift  Edema Ventricles  Compression, blood, or hydrocephalus Subarachnoid cistern compression
  •  The head contains four things (skull, brain, blood, spinal fluid)  The CT is reviewed to make sure all four are in the right amount and location The brain is symmetrical; asymmetry is abnormal The cerebral hemispheres are mirror image structures - what is on the left should be on the right
  •  Prior contrast reaction (“iodine allergy”) Poor renal function  Creatinine > 2.0 Lack of consent Suspend breast feedings for 24 hours following I.V. contrast Shellfish and/or Betadyne allergies are not contraindications
  • A. Orbit B. Sphenoid Sinus C. Temporal Lobe D. External Auditory Canal A. Orbit E. E. Mastoid Air Cells Mastoid Air Cells B. Sphenoid Sinus F. F. Cerebellar Hemisphere Cerebellar Hemisphere C. Temporal Lobe D. External Auditory CanalUsed with permission University of Virginia Health Sciences Center
  • A. Frontal LobeB. Frontal Bone(Superior Surface of Orbit)C. Dorsum SellaeD. Basilar ArteryE. Temporal LobeF. Mastoid Air CellsG. Cerebellar Hemisphere
  • A. Frontal Lobe B. Sylvian Fissure C. Temporal Lobe D. Suprasellar Cistern E. Midbrain F. Fourth Ventricle G. Cerebellar HemisphereUsed with permission University of Virginia Health Sciences Center
  • A. Frontal Lobe B. Falx Cerebri C. Anterior Horn of Lateral Ventricle D. Third Ventricle E. Quadrigeminal Plate Cistern F. CerebellumUsed with permission University of Virginia Health Sciences Center
  • A. Anterior Horn of the Lateral Ventricle B. Caudate Nucleus C. Anterior Limb of the Internal Capsule D. Putamen and Globus Pallidus E. Posterior Limb of the Internal Capsule F. Third Ventricle G. Quadrigeminal Plate Cistern H. Cerebellar Vermis I. Occipital LobeUsed with permission University of Virginia Health Sciences Center
  • A. Genu of the Corpus Callosum B. Anterior Horn of the Lateral Ventricle C. Internal Capsule D. Thalamus E. Pineal Gland F. Choroid Plexus G. Straight SinusUsed with permission University of Virginia Health Sciences Center
  • A. Falx Cerebri B. Frontal Lobe C. Body of the Lateral Ventricle D. Splenium of the Corpus Callosum E. Parietal Lobe F. Occipital Lobe G. Superior Sagittal SinusUsed with permission University of Virginia Health Sciences Center
  • A. Falx Cerebri B. Sulcus C. Gyrus D. Superior Sagittal SinusUsed with permission University of Virginia Health Sciences Center
  • Supracellar cisterrn (can you visualize the “star” shape)Fourth Ventricle F = frontal lobes U = uncus (medial temporal lobes) Po = Pons
  • Dura (retracted) Bridging vein(s)
  • Subdural bleed
  • 1 - Anterior Fossa2- Posterior Fossa3- Frontal Sinus4- Esphenoid Sinus5- Tentorium Cerebelli
  •  Majority are due to aneurysms or arterioventricular malformations (AVM) Bleeding is into the CSF space Ability to diagnose with CT decreases with time: ▪ 95% positive at 12 hours ▪ 80% positive at 3 days ▪ 30% positive at two weeks
  • Berry aneurysm
  •  Below the dura but above the arachnoid Usually venous in origin  Commonly a ruptured bridging vein (dural drainage)  Cresent or sickle shaped pattern on CT Can cross suture lines Common in elderly or anti-coagulated Density of blood determines the age of the bleed:  Acute  Chronic
  •  aka “intracerebral” hemorrhage Can follow hypertensive stroke Can follow deceleration (“contusion”) injuries Can extend into the ventricles (intracerebral extension)
  •  Hemorrhage into the ventricular system Can be an extension of an intraparenchymal or subarachnoid bleed Can be secondary to trauma (poor outcome) Not uncommon in extremely premature infants Obstructive hydrocephalus can be a complication
  •  Arterial blood  Usually secondary to a linear skull fracture through an arterial channel (like the middle meningeal artery) Biconvex shape (lens shaped) Bleeding may cross the midline Bleeding won’t cross suture lines A subdural and an epidural may occur together Epi vs. sub doesn’t matter – but volume does  > 5 mm or > 10 mm in adults = surgical evacuation
  • Early ICP Findings Late ICP Findings Headache  Cushings triad Vomiting  Hypertension Vision distortion  Bradycardia Decreased sensorium Papilledema possible  Flexor/extensor posturing  Pupillary dysfunction
  •  Haydel MJ, Preston CA, Mills TJ, Luber S, Blaudeau E, DeBlieux PM. Indications for computed tomography in patients with minor head injury. N Engl J Med. 2000;343:100-5. Stiell IG, et al. Comparison of the Canadian CT Head Rule and the New Orleans Criteria in patients with minor head injury. JAMA. 2005;294:1511-8. www.aafp.org/online/en/home/clinical/clinica lrecs/headinjurychild.html
  •  Basic properties Skull fractures Suture lines versus fracture lines Basilar skull fracture Child abuse and skull fractures
  •  Fracture in any location other than parietal location Non-linear fracture Linear fracture length exceeding 6 cm Fracture crossing suture lines
  •  The bone windows information is part of the routine CT head and is ideal for viewing fractures Sinuses can be seen well with bone windows The scout film of the CT scan is roughly the equivalent of a lateral skull x-ray film – so look at it too Remember to look at the overlying soft tissue for swelling as it may point to an underlying skull fracture
  •  Skull fractures may be classified as either linear or comminuted  Inwardly displaced comminuted = depressed skull fx ▪ A depressed skull fracture requires immediate neurosurgical evaluation Cranial sutures can be confused with linear fractures
  • Suture Fracture Characteristic locations Usually temperoparietal Symmetrical line on other side Asymmetrical Same size throughout Widest at the center/ narrow at the end Graceful curvy lines Straight lines with angular turns
  •  A fracture of the orbital roof, sphenoid bone, or mastoid portion of temporal bone Usually resolve on their own but can be:  Displaced  Cranial nerve damage (II, VII, VIII)  CSF leak (otorhea or rhinorhea) “Classic” clinical findings may (or may not) be present
  •  Hemotympanum Periorbital bruising ("raccoon eyes“) Cerebrospinal fluid otorrhea or rhinorrhea Battles sign (Mastoid eccymoses) Pneumocephalus  (Air and fluid/levels in sinuses)
  •  Superior to inferior  Falx cerebri  Body of lateral ventricles  Internal capsule and thalamus  Caudate and third ventricle  3rd Ventricle and quadrigeminal cistern  Supracellar cistern and 4th ventricle
  • Extra-axial hemorrhage Intra-axial hemorrhage(outside the brain) (inside the brain)  Subarachnoid (SAH) Epidural  Below the arachnoid membrane  Below the skull  On the surface of the brain  “above” the dura  Intraparenchymal (IPH) Subdural  Within the substance of the  Below the dura brain  Above the thin, spidery-like  Intraventricular (IVH) arachnoid membrane  Within the ventricles
  •  CSF-filled balloons  CSF Direction of Flow: CSF is produced in the  Lateral ventricles choroid plexes,  Foramen of Monroe “circulates” through  Third ventricle the ventricular system,  Cerebral aqueduct percolates over the  Fourth ventricle surface of the cord and  Foramen (Magendie and brain, and is absorbed Lushka) in the arachnoid  Subarachnoid space granulations  Arachnoid granulations  Venous circulation
  •  Size  Large = too much fluid or brain atrophy  Small = Compression (edema or mass) Symmetry  Asymmetry = impingement from mass/edema, etc. Presence of blood  IVH can lead to secondary hydrocephalus Anatomic landmarks  Lateral and 3rd ventricle are supratentorial ▪ 3rd is located anterior to the pineal gland ▪ Looks like an exclamation point  4th ventricle is infratentorial ▪ Looks like a pith helmet (roundish)
  •  Considerations Ventricular system CSF circulation CT images:  Hydrocephalus  Asymmetry (impingement from tumor)  IVH
  •  A tough, fibrous structure separating the cerebrum above and the cerebellum and brain stem below Provides support for the cerebrum Structures above the tentorium are known as supratentorial or anterior fossa Structures below the tentorium are known as infratentorial or posterior fossa
  • 1 - Anterior Fossa2- Posterior Fossa3- Frontal Sinus4- Esphenoid Sinus5- Tentorium Cerebelli
  • Frontal Parietal Occipital Temporal
  • Note collection of blood above the dura mater Dura mater
  • Ruptured berry aneurysm
  •  Majority can be visualized without contrast  Contrast is indicated if brain tumor is suspected and not see on noncontrast study Appear as edematous, low density, poorly- defined lesions Classified as intraaxial (within the brain tissue) or extraaxial Adult tumors are usually supratentorial while pediatric tumors are usually infratentorial Many metastatic tumors will be located at the gray-white matter border(s)
  •  General considerations Brain tumors  Meningioma  Astrocytoma (pediatric)
  •  Cystic mass in the midline of the cerebellum (red arrows) Note early hydrocephalic changes secondary to tumor compression (yellow arrows)
  •  Red arrow points to a large cerebellar hemorrhageUsed with permission University of Virginia Health Sciences Center
  •  Cocaine induced hypertensive CVA  Note the large hemorrhagic lesion in the left cortical area as well as multiple smaller regions (redness) near the hippocampus and other cortical regions.www.utsa.edu/tsi/assign/anat/neuropat.htm
  •  Loss of the gray- white interface in the lateral margins of the insula The cortex of the left insular ribbon is not visualized (arrow). Right insular ribbon is outlined in yellow
  •  Contrast enhanced CT of meningioma (most common extraxial brain tumor)
  • Used with permission by the CRASH Trials with credit to Mr. J. Wasserberg and Mr. B. Mitchell
  • A. Falx Cerebri B. Frontal Lobe C. Body of the Lateral Ventricle D. Splenium of the Corpus Callosum E. Parietal Lobe F. Occipital Lobe G. Superior Sagittal SinusUsed with permission University of Virginia Health Sciences Center
  • Edema  The darker gray Edema areas represent Blood Blood edema while the white areas represent the intracerebral contrusion (“bruise”)Used with permission by the CRASH Trials with credit to Mr. J. Wasserberg and Mr. B. Mitchell
  • Used with permission by the CRASH Trials with credit to Mr. J. Wasserberg and Mr. B. Mitchell
  •  Small red arrows point to a biconvex epidural hematoma secondary to a skull fracture (large red arrow)Used with permission University of Virginia Health Sciences Center
  •  Red arrows denote blood within the sulci of the right cerebral convexityUsed with permission University of Virginia Health Sciences Center
  •  The large red arrow points to blood within the ventricle while the smaller red arrows point to blood in the sulci (subarachnoid hemorrhage)Used with permission University of Virginia Health Sciences Center
  •  Linear skull fracture (parietal location) found on bone windows image
  • Frontal Parietal Occipital Temporal
  •  The cortical areas of the brain devoted to motor (frontal motor strip) and sensory (parietal sensory strip) function can be represented as an “upside” down person. A disruption in cerebral blood flow to these areas will result in a corresponding sensory and/or motor deficit to the corresponding region.
  • Artery Lobes Supplied DeficitACA Frontal Leg weaknessMCA Frontal Speech Lateral Temporal Motor and sensory Lateral Parietal to hand and armPCA Temporal Visual defects Occipital
  • Normal MRIPatient MRI