2By the end of this tutorial, you will be able to recognize some of the common radiologic problems most often seen by physicians. Hopefully, you will also become more aware of what tests to order and when to order them. We also hope that you will have a little fun in the process!
3CT Anatomy (you kind of need to know this) A = Frontal sinusB = OrbitC = Frontal lobeD = Sphenoid sinusE = Temporal lobeF = External auditory canalG = Mastoid air cellsH = Cerebellar tonsilI = Foramen magnum
14Coronal MRI Anatomy A = Intrahemispheric fissure B = Corpus callosum C = Lateral ventricleD = Suprasellar cisternE = Temporal lobeF = Insular cortexG = Sylvian fissure
15A = Superior sagittal sinus B = Corpus callosumC = Septum pellucidumD = Lateral ventricleE = Caudate nucleusF = Internal capsuleG = Interventricular foramen of MonroH = Third ventricleI = Insular cortex
16A = Corpus callosum (splenium) B = Choroid plexus of the lateral ventricleC = Hippocampal formationD = Quadrigeminal cisternE = Fourth ventricleF = Cerebellar hemisphereG = Tentorium cerebelli
17Sagittal MRI Anatomy A = Corpus callosum B = Fornix C = Thalamus D = Optic chiasmE = Pituitary glandF = PonsG = Dens (C2 vertebra)H = Spinal cordI = Pineal glandJ = Tectum (midbrain)K = Cerebral aqueductL = Tegmentum (midbrain)M = Fourth ventricleN = Medulla
18Circle of Willis A = Basilar artery B = Posterior cerebral artery C = ThalamoperforatorsD = Posterior communicating arteryE = Internal carotid arteryF = Middle cerebral arteryG = Anterior cerebral arteryH = Anterior communicating artery
19Vascular Territories A = Anterior cerebral artery B = Middle cerebral arteryC = Posterior cerebral arteryD = Lenticulostriate arteries
20A 82 y/o female presents with sudden onset of right-sided weakness and garbled speech for 3 hours. What, if any, radiologic test would you order, and why?Read about the following imaging techniques to help you formulate an answer:
22CT vs. MRI: What to order? MRI CT Acute neurological events: StrokeTraumaWorst HA of lifeAcute mental status changeFirst seizureNeurosurgery immediate post-opFollow up:Acute infarctsHemorrhageHydrocephalusMRIAcute (usually after CT):StrokeEncephalitisSubacute and chronic:Progressive, subacute, or chronic neurological deficitTIAs, h/o of strokeBrain tumorsMetastatic diseaseDementiaEpilepsyChronic headachesMSDevelopmental delayPituitary disordersCranial nerve dysfunction
23CT Head For acute neurologic eventsCT of the head without IV contrast The most frequent reason that a CT head is ordered is for the diagnosis of CVA’s and ICHDoes not exclude infarct in acute stage of a stroke, but is useful to exclude a bleed (so anticoagulant medication can be commenced)IV contrast is not routinely used, but may be useful for evaluating tumors, cerebral infections, and sometimes for the evaluation of stroke patients.
24CT HeadCT can also be used to detect increases in intracranial pressure, e.g. before lumbar puncture or to evaluate the functioning of a VP shunt.CT is used in trauma for evaluating facial and skull fractures.In order to prevent unnecessary irradiation of the orbits and especially the lenses, head CTs are performed at an angle parallel to the base of the skull, with the patient in the supine position.Slice thickness generally is between 5 and 10 mm
25MRI Currently, MRI with Diffusion Weighted Imaging: MRI is also performed for possible brain stem and posterior brain pathology, that is not readily seen on CTCurrently, MRI with Diffusion Weighted Imaging:Is superior to CT in detecting acute infarctsIs less sensitive than CT for SAH and hyperacuteparenchymal hemorrhageHas no exposure to radiation, but takes longer to get study done
26Imaging Techniques CT MRI-T1 MRI-T2 Bone Bright Dark Air Fat Water BrainIntermedGray=grayWhite=white
29CT Angiography (CTA) Advantages: Disadvantages: Noninvasive Faster than MRA or AngiographyExcellent for measuring lesionsEasily demonstrates intraluminal clots and extravascular hematomasDisadvantages:Radiation exposureUse of contrast materialCan be diagnostic, but may require invasive therapeutic measures
30Magnetic Resonance Angiography (MRA) Advantages:-Noninvasive-Iodinated Contrast not needed-Safe for patients with renal insufficiency-Images can be reconstructed in any plain-Does not require the use of radiation-Depicts both anatomy and flow rateDisadvantages:-Can not be used in patients with pacemakers or certain hardware-Long acquisition time-Poor spatial relations-Can be diagnostic but may require invasive therapeutic measures
31Angiogram Advantages: Disadvantages: Can be diagnostic and theurapeuticAlthough invasive, if a clot or aneurysm is seen, intervention can be done at the time of the procedureDisadvantages:InvasiveUse of Contrast MaterialPossible Kidney failureLengthy post-procedure precautions for bleeding from insertion site
32A 82 y/o female presents with sudden onset of right-sided weakness and garbled speech for 3 hours. What, if any, radiologic test would you order, and why?Answer: CT of head without IV contrast. Why, you ask? As you can see from the above info, both IV contrast and an acute bleed will show up bright on CT. You must first rule out hemorrhage in any acute stroke patient, so that appropriate therapy can be started. You wouldn’t want to start thrombolytic therapy on someone who is actively bleeding!!!
33Mini QuizWhich of the following is NOT true concerning the process of performing a head CT? A. Head CTs are performed at an angle parallel to the base of the skull. B. Slice thickness is generally between 5 and 10 mm. C. Intravenous contrast is routinely used. D. The patient is placed in a supine position on the table.
3568 y/o with left-sided weakness and confusion CT Head w/o Contrast
36Ischemic Stroke Ischemic strokes account for 84% of all strokes Causes:ThrombosisBlood clot forms in one of the cerebral arteries from hypercoagulable state, rupture of atherosclerotic plaque, or underlying stenosisMay be preceded by transient ischemic attack (TIA)EmbolismDetached clot from heart or large vessels such as carotidAfib is a common causeHypoperfusionProximal stenosis of cerebral arteryCardiac or respiratory failureLacunar infarctionswalls of small arteries thicken and cause the occlusion of the arteryinvolve the small perforating vessels of the brain and result in lesions that are less than 1.5 cm in size.Sharply circumscribed hypodense edema (arrowheads) in the right middle cerebral artery territory
37Early CT findings in acute infarct May be normal in first ~ 12 hoursLoss of gray-white matter differentiationLoss of bright cortical ribbonSubtle hypodensity (cytotoxic edema)Loss of bright basal gangliaSwelling/sulcal effacementHyperdense artery signArtery must be brighter than other Circle of Willis arteriesArtery in question must fit clinical pictureCT showing acute infarct with loss of gray-white matter differentiation (arrows) and sulcal effacement
3879 y/o female with HA and ataxia CT Head w/o contrast
39Hemorrhage in the left posterior parietal lobe (arrow) Hemorrhagic StrokeHemorrhagic strokes are due to rupture of a cerebral blood vessel that causes bleeding into or around the brain.2 Types (intracerebral and subarachnoid)IntracerebralHypertensive hemorrhage (most common cause)Predilection for deep structures of the brain, such as thalamus, pons, cerebellum, and basal gangliaAmyloid angiopathyRuptured vascular malformationCoagulopathyHemorrhage into a tumorDrug AbuseHemorrhage in the left posterior parietal lobe (arrow)
4028 y/o female with “worst HA of my life” CT head w/o contrast
41Subarachnoid Hemorrhage Main causes:Trauma #1Ruptured cerebral aneurysmOther Causes:AVM ruptureCoagulopathyVasculitisNeoplasmPituitary apoplexyHypertensionVenous rupture/venous thrombosisNONCONTRAST CT is the imaging of choice for nontraumatic SAHIf CT is negative and there is still a strong clinical suspicion→ LP may be used for the diagnosisDetection of a subarachnoid hemorrhage is crucial because the rehemorrhage rate of ruptured aneurysms is high and rehemorrhage is often fatal.On CT, a subarachnoid hemorrhage appears as high density within sulci and cisterns.High density blood fills the third ventricle and is in the sylvian fissure in this subarachnoid hemorrhage.
42After positive SAH on CT or lumbar puncture: Cerebral (catheter) angiography: “Gold standard”InvasiveTime and labor intensiveSmall risk of complications (stroke, contrast reaction)CTA—best first exam; replaces cerebral angiography in many casesMinimally invasive (IV injection)Very fastModerately labor intensiveMay still need catheter angiography if CTA is negative, or aneurysm not well delineatedIodinated contrast risk
4325 y/o with new onset seizures CT head w/o contrast
44Arteriovenous Malformation with Hemorrhage Underlying AVM may or may not be visible on CT scanProminent vessels adjacent to the hematoma suggest an underlying arteriovenous malformationSome arteriovenous malformations contain dysplastic areas of calcification and may be visible as serpentine enhancing structures after contrast administration.The CT on the top shows hemorrhage (arrow) due to underlying AVM (arrowheads). The arteriogram on the left shows the tangle of vessels (arrowheads) of the AVM. This lesion would be considered for intravascular embolic therapy.
45The most important issue to determine when imaging a stroke patient is whether a hemorrhagic or ischemic event has occurred.B. FalseA. True
46Which of the following is NOT true concerning stroke? B. An embolic stroke occurs when a detached clot flows into and blocks a cerebral artery. C. Global anoxia presents an ischemic challenge to the brain and is classified as a hypoperfusion infarction. D. The most common cause of non-traumatic intracerebral hematoma is hypertensive hemorrhage.A. Hemorrhagic stroke is more common than ischemic stroke.
47In which of the following locations is hypertensive hemorrhage LEAST LIKELY to occur? A. Thalamus B. Cerebellum C. Basal Ganglia D. PonsE. Occipital Lobe
48Which of the following is NOT true concerning CT of a stroke patient? A. Patients who have a hypertensive hemorrhage may have extension of blood into the ventricular system. B. An acute infarct may be normal on CT for the first 12 hours.D. On CT, prominent vessels adjacent to a hematoma suggest an underlying arteriovenous malformation.C. The underlying arteriovenous malformation causingstroke is almost always visible on CT scan.
49Which of the following is NOT a CT finding in an acute infarct. A Which of the following is NOT a CT finding in an acute infarct? A. Loss of gray-white distinctionB. Subtle hypodensity due to cytotoxic edemaC. Hyperdensedense basilar or middle cerebral artery corresponding to thrombus in the affected vessel.E. Sulcal effacementD. Dysplastic areas of calcification
50Which of the following is NOT true concerning subarachnoid hemorrhage Which of the following is NOT true concerning subarachnoid hemorrhage? A. Appears as high density within sulci and cisterns. B. Noncontrast CT is the imaging of choice for suspected SAH. D. Cerebral angiography is the “gold standard.” E. Subarachnoid hemorrhage occurs most commonly with traumaC. The rehemorrhage rate of a SAH is low.
53Linear skull fracture of the right parietal bone (arrows). The bone windows must be examined carefully.A skull fracture is most clinically significant if the paranasal sinus or skull base is involved.Raccoon EyesBattle’s SignSkull fractures are categorized as linear or depressedLinear fractures are more common, resembling a thin line w/o distortion or depression of boneDepressed fractures are breaks in bone with depression of bone in towards brainFractures must be distinguished from sutures that occur in anatomical locations (sagittal, coronal, lambdoidal) and venous channels.Sutures have undulating marginsBoth sutures and venous channels have sclerotic margins.Venous channels have undulating sidesLinear skull fracture of the right parietal bone (arrows).
55Traumatic Intraventricular Hemorrhage Traumatic intraventricular hemorrhage is associated with diffuse axonal injury, deep gray matter injury, and brainstem contusion.An isolated intraventricular hemorrhage may be due to rupture of subependymal veins.As you can see, this patient also has a SAH, which, if you remember, is most commonly caused by TRAUMA!-The ruptured vessel bleeds into the space between the pia and arachnoid matter.-The most common location of posttraumatic subarachnoid hemorrhage is over the cerebral convexity.-This may be the only indication of cerebral injury.Intraventricular hemorrhage (arrow) found in a trauma patient. Note the subarachnoid hemorrhage in the sulci in the subarachnoid space (arrowheads).
5647 y/o alcoholic “found down” CT head w/o contrast
57Subdural HematomaDeceleration and acceleration or rotational forces that tear bridging veins can cause an acute subdural hematoma.The blood collects in the space between the arachnoid matter and the dura matter.SubacuteCompressed lateral ventricleEffaced sulciWhite matter “buckling”Thick cortical “mantle”AcuteCrescent shaped, concave toward brainTapering edgesCrosses suture linesMay extend into interhemispheric fissureFracture may or may not be presentHyperdense, may contain hypodense foci due to serum, CSF or active bleedingHigh density, crescent shaped hematoma overlying the left cerebral hemisphere. Note the shift of the normally midline septum pellucidum due to the mass effect
5819 y/o post fist fight-5 hours later has acute LOC CT head w/o contrast
59Epidural HematomaAn epidural hematoma is usually associated with a skull fracture.The fractured bone lacerates a dural artery or a venous sinus.Most common artery involved is the middle meningeal arteryThe blood from the ruptured vessel collects between the skull and dura.Hyperdense, lens shaped (lenticellular) biconvex massAbrupt edgesDoes not cross suturesCannot extend into interhemispheric fissureBiconvex mixed hyperdense and hypodense lesion overlying the left frontal cortex. Notice that it does not cross suture lines.
6047 y/o status-post car vs. tree CT head w/o contrast
61Diffuse Axonal InjuryDiffuse axonal injury is often referred to as "shear injury“, caused by acceleration, deceleration, and rotational forcesPortions of the brain with different densities move relative to each other resulting in the deformation and tearing of axons.Immediate loss of consciousness is typical of these injuries.The CT of a patient with diffuse axonal injury may be normal despite the patient's presentation with a profound neurological deficit.May appear as ill-defined areas of high density or hemorrhage in characteristic locations, listed from most likely location first followed by successively less likely locations: - Subcortical white matter - Posterior limb internal capsule - Corpus callosum - Dorsolateral midbrainHemorrhage of the posterior limb of the internal capsule (arrow) and hemorrhage of the thalamus (arrowhead).
6292 y/o restrained driver in MVA CT head w/o contrast
63Cerebral ContusionsCerebral contusions are the most common primary intra-axial injury, caused by coup/contrecoup injuryThey often occur when the brain impacts an osseous ridge or a dural fold. Multiple petechial hemorrhage or edema are located along gyral crests.The following are common locations: - Temporal lobe - anterior tip, inferior surface, sylvian region - Frontal lobe - anterior pole, inferior surface - Dorsolateral midbrain - Inferior cerebellumOn CT, cerebral contusion appears as an ill-defined hypodense area mixed with foci of hemorrhage.After hours, hemorrhagic transformation or coalescence of petechial hemorrhages into a rounded hematoma is common.Multiple foci of high density corresponding to hemorrhage (arrows) in an area of low density (arrowheads) in the left frontal lobe due to cerebral contusions.
64Which of the following is NOT true concerning acute subdural hematoma Which of the following is NOT true concerning acute subdural hematoma? A. Tearing of bridging veins causes acute subdural hematoma. C. The hematoma is crescent shaped on CT. D. The hematoma may extend into hemispheric fissureB. The hematoma is lenticellular in shape on CT.
65The most common cause of subarachnoid hemorrhage is trauma. B. FalseA. True
66Which of the following is NOT a characteristic of subacute subdural hematoma? A. Compression of the lateral ventricle on the side of the hematoma. B. Effaced sulci. C. White matter buckling. D. Thick cortical mantle.E. Insular ribbon sign.
67Which of the following is NOT true regarding a epidural hematoma? A. Caused by laceration of dural artery or venous sinusC. Blood collects between the skull and the duraD. Blood does not cross suture linesB. Not usually associated with a skull fracture.
68Which of the following is NOT true concerning subacute subdural hematoma? B. It should be suspected when there is a midline shift of structures without an obvious mass present. C. On CT, the hemorrhage is hyperdense to normal gray matter. D. Blood collects in the space between the arachnoid matter and the dura matter.A. Contrast is often used to visualize the hematoma on CT.
7065 y/o WM with mental status changes and left sided weakness CT head w/o contrastCT head with contrast
71Glioblastoma Multiforme Glioblastoma Multiforme is the most aggressive grade of astrocytoma.On CT, GBM is characterized by necrosis and irregular enhancement.It is one of very few lesions that frequently cross the corpus callosum.Differentiating Intra-axial tumors:Tumor completely surrounded by brainEffaced CSF spacesGray–white junction not displaced inwardCortical vessels not displaced inwardBone normal(rare: remodeling of inner table in cortical tumors)An image post contrast administration in the same patient reveals patchy enhancement, a portion of which is crossing the corpus callosum (arrow).
73MeningiomaMeningiomas are the most common extra-axial neoplasm of the brain.Twenty percent of meningiomas calcify.On CT, meningiomas are usually isointense to gray matter.Differentiating Extra-axial tumorsTumor borders on CSF spaceEnlarged CSF spaces at edges of massGray–white junction displaced inwardCortical vessels displaced inwardBone may have hyperostosis (meningioma) or remodelingOn this T2 weighted MRI this meningioma is extra-axial and compressing adjacent brain structures, displacing the gray-white junction inward. Notice the “crinkling” of the displaced brain.
7453 y/o male with hx of melanoma, with headache and gait disturbance CT head w/o contrastCT head with contrast
75Metastatic TumorsMetastatic tumors are the most common intracranial tumors in adults.Most common sites are from lung, breasts, melanoma, renal, and colon.Mets commonly occur at the corticomedullary junction, and the edema pattern is usually larger than the tumorUnenhanced and enhanced CT show multiple high attenuation lesions without contrast, with enhancement after contrast, as well as surrounding edema
76True or False1. Lymphomas are the most common extra-axial neoplasm of the brain. A. True2. On CT, meningiomas are usually isointense to gray matter. B. False3. MRI is more sensitive than CT for meningioma. B. False4. Like most tumors, glioblastoma multiforme does not cross the corpus callosum. A. True5. On CT, glioblastoma multiforme is characterized by necrosis and irregular enhancement.B. FalseB. FalseA. TrueA. TrueB. FalseA. True
7874 y/o male with chronic memory loss and impaired executive function CT head w/o contrast
79Alzheimer’sBecause of its low sensitivity and specificity for the diagnosis of Alzheimer's disease, imaging is typically not used to rule in Alzheimer's disease but rather to rule out other causes of dementia.Nevertheless, in the right clinical context Alzheimer's disease appears radiographically as diffuse cerebral atrophy with enlarged lateral ventricles and widened sulci on CT.Large cortical neurons in the transentorhinal region are the major types of neurons that undergo this degeneration. This process begins focally in the fronto/temporal lobes (primarily the entorhinal cortex and hippocampal regions) succeeded by the parietal lobes and finally the occipital lobes.The neuronal loss is severe resulting in marked, diffuse atrophy that may be as much as 10-30% of the total brain massIn this CT, you can see enlarged ventricles with atrophy of the cerebral hemispheres without any other visible causes of the dementia
81Cerebral AtrophyCerebral atrophy refers to the wasting away of brain tissue and cells that occurs as part of normal agingIt is important to distinguish if atrohy is “normal for patient age”See widening of sulci and narrowing of the gyriCerebral atrophy can also be secondary toStrokeAlzheimer’sPick’s DiseaseInfectiousHuntington’sCerebral palsyDrugsHIVCT shows diffuse atrophy with widened Sylvian cisterns
8265 y/o male with resting tremor and masked facies T2-MRI
83Parkinson’s DiseaseA clinical syndrome, Parkinson's disease is clinically evident by its triad of bradykinesia and hypokinesia, resting tremor, and increased tonicity of voluntary musculature and loss of postural reflexes.There is a selective loss of neuromelanin containing dopaminergic neurons within the pars compacta of the substantia nigra, and the disease manifests itself when 80% of these neurons are lost.Radiographically Parkinson’s disease appears as nonspecific atrophy with enlarged lateral ventricles and widened sulci on CT.On MR, decreased width of the pars compacta between the pars reticularis and the red nucleus may be evident.There is no cure for Parkinson's disease.The arrows indicate areas of decreased width of the low signal intensity pars compacta within the substantia nigra.
8452 y/o male with spastic flailing of extremities CT head w/o contrast
85Huntington’s DiseaseHuntington’s disease is a progressive neurodegenerative disorder characterized by choreoathetoid movements, behavioral disturbances, and progressive dementia.Huntington's disease is a known genetically linked disorder with autosomal dominant inheritance and complete penetrance.Huntington's disease is caused by a trinucleotide repeat that is found within the huntingtin gene located on chromosome 4.Grossly changes are initially manifested by striatal atrophyDegeneration occurs most prominently in the caudate tail followed by the body, head, and eventually the putamen and nucleus accumbens.By the time the disease reaches its terminal phases, 20-30% of the total brain mass may be reduced.There is no cure for Huntington's disease, and it is universally fatal.The image on the left exhibits bilateral caudate head atrophy (red arrowheads), as seen by a decrease in the medial convexities, & lateral ventricle dilatation. Generalized atrophy evident as diffusely widened sulci is also apparent in the image on the left
8672 y/o male preacher with seductive behaviors, cussing, and dementia CT head w/o contrast
87Pick’s DiseasePick’s Disease is a neurodegenerative disorder that is clinically evident as behavioral and language disturbances out of proportion to memory deficits.Following Alzheimer’s disease and diffuse Lewy body disease, Pick’s disease is the third most common neurodegenerative cortical dementia.Due to severe neuronal loss and gliosis, atrophy becomes readily apparent in those regions of the cortex most commonly affected, the frontal and temporal lobes.This atrophy may be asymmetric.Currently there is no treatment.Focal bifrontotemporal atrophy can be seen, as exhibited by marked widening of the frontal and temporal sulci, dilation of the lateral ventricles, and the "knife-like" projections of the gyri.
88Imaging is typically used to rule in the diagnosis of Alzheimer's disease. A. TrueB. False
89Huntington's disease is characterized by the selective degeneration of neurons within the striatum. B. FalseA. True
90The process responsible for Alzheimer's disease begins focally in the _______________. A. parietal lobesB. occipital lobesD. brainstemC. fronto/temporal lobes
91On axial T2-weighted MRI, decreased width of the pars compacta may be evident in patients with Parkinson's disease.B. FalseA. True
92On CT, Huntington's disease appears as _________________________________. B. Decrease in the relative volume of the lateral ventricles.C. Both A and B.D. Neither A nor B.A. Decrease in the convexity of the caudate heads bilaterally.
93On CT in Pick's disease, one might observe which of the following? A. widening of the Sylvian fissureB. atrophy of the inferior frontal and superior temporal lobesC. sulcal prominenceD. enlargement of the frontal horns of the lateral ventriclesE. all of the above
955 month old with HA, neck stiffness, and photophobia
96Diffuse leptomeningeal enhancement can be seen overlying the cortex MeningitisThree subtypes of meningitis.Acute pyogenic meningitis is usually bacterial.Lymphocytic meningitis is usually viral, benign and self-limited.Chronic meningitis is often seen in immunocompromised hosts and may be fungal or parasitic.Imaging usually on done to look for complications and assess for safety of LPImaging is usually normal, so it is not usually performed for diagnosisDiffuse leptomeningeal enhancement can be seen overlying the cortex
97MeningitisCommon complications of meningitis that can be seen using imaging techniques:HydrocephalusVentriculitis/ EpendymitisSubdural effusionSubdural empyemaCerebritis/ AbscessVasospasmThe development of cerebrovascular problems is the most common complication of meningitis.Arterial infarction can occur which often affects the basal ganglia due to the occlusion of small perforating vessels.Hemispheric infarction can also occur due to major vessel spasm.Venous infarctions are also common and can include cortical venous occlusion or the involvement of the superior sagittal sinus.
9823 y/o male with acute mental status change CT head w/o contrastDWI-MR
99Herpes Encephalitis MRI with DWI highly sensitive CT may be negative or misinterpreted as infarct/tumor early in courseAnterior temporal lobes, basal frontal lobes, cingulate cortex, insular cortex (limbic system)Spares basal gangliaBilateral ~ 50%Hemorrhage or enhancement not until subacute or chronic phaseAs you can see, CT appears normal, but on DWI MR, the right temporal lobe lights up (arrow)
10019 y/o male with hx of meningitis with continued fever and confusion CT head with contrast
101Ventriculitis/Ependymitis Ventriculitis is characterized by inflammation and enlargement of the ventricles.Ependymitis shows hydrocephalus with damage to the ependymal lining and proliferation of subependymal glia.A CT of patients with these conditions reveals the presence of periventricular edema and subependymal enhancement.Ventriculitis and Ependymitis affect approximately 30% of the adult patients and 90% of the pediatric patients with meningitis.In this post contrast CT scan, note the ring enhancing brain abscess (arrowheads) and enhancement of the ependymal lining of the atrium by the left lateral ventricle (arrow)
10235 y/o female with HA and fever T1-MRI with Gad
103Notice the mass ring enhancing mass (arrows) with surrounding edema Brain AbscessRing enhancing mass(es) with edemaLocation: anywhere, often gray-white junctionWall of abscess uniform width; may be thinner at deep marginDdx: Necrotic glioma, metastases (irregularly thick, nodular walls)CT & MR with contrast both highly sensitiveDWI: very bright in abscessDdx: necrotic tumorMR spectroscopy accurate for abscess vs. necrotic tumorNotice the mass ring enhancing mass (arrows) with surrounding edema
10435 y/o AIDS patient with fever, HA, and seizures
105Multiple ring enhancing lesions seen at many levels (arrows) ToxoplasmosisCaused by a single celled parasite called Toxoplasma gondiiTypically seen in immunocompromised or infants born to mothers with an active infection during pregnancyMay infect the brain, lung, heart, eyes, or liverMay appear as multiple ring enhancing lesionsMRI is considered the best imaging technique for toxoplasmic encephalitisMultiple ring enhancing lesions seen at many levels (arrows)
106Ring-enhancing brain lesions Lots of things can show up as ring-enhancing lesions, so even though it sounded really cool in medical school, it is really not very specific!“MAGICAL DR”MetastasisAbscessGlioblastoma/high grade glial neoplasmInfarct (subacute; esp. in deep gray nuclei)Contusion (subacute)AIDS (Toxo)Lymphoma (in immunocompromised)Demyelinating lesionResolving hematoma (subacute)
107Imaging studies of patients with meningitis are frequently normal despite the presence of the disease. B. FalseA. True
108Typical findings on CT of patients with ventriculitis or ependymitis are periventricular edema and subependymal enhancement.B. FalseA. True
109Which of the following is NOT true concerning cerebrovascular complications of meningitis? A. The development of cerebrovascular problems is the most common complication of meningitis. B. Arterial infarction can occur and often affects the basal ganglia. C. Major vessel spasm can occur causing hemispheric infarction. D. Complications of meningitis can include cortical venous occlusion.E. Venous infarctions resulting from meningitis do not involve the superior sagittal sinus.
110A ring enhancing lesion is diagnostic of toxoplasmosis A. TrueB. False
11267 y/o male with gait disturbance, dementia, and urinary incontinence CT head w/o contrast
113Hydrocephalus Abnormal buildup of CSF in the brain Two types CommunicatingInadequate reabsorption of CSFNonobstructingNoncommunicatingBlockage of CSFCan be associated withTumorsTraumaMeningitisArachnoid cystsCongenitalSAHNormal pressure hydrocephalusCT shows enlargement of bilateral lateral ventricles with shrinking of adjacent brain matter
11438 y/o female with numbness in LUE T2 MRIT2 MRI
115Multiple Sclerosis MRI: imaging study of choice MS is due to myelin loss in multiple areas leading to sclerosisSmall, discrete white matter lesions:Periventricular (esp. perpendicular to ventricle)Peripheral brainstemUndersurface of corpus callosumSubcortical white matterVariable enhancement; usually no edemaT2 weighted MRI showing “plaques” (arrows) in both the brain and the spinal cord
116Final Quiz (cross your fingers, because you’re almost done!)
117B. The hematoma may cross suture lines. Question 1: Which of the following is NOT true concerning epidural hematoma? A. Epidural hematoma is caused by the laceration of a dural artery or venous sinus by a fracture.C. On CT, the hematoma forms a hyperdense, biconvex mass. D. On CT, the hematoma may contain hyperdense foci due to active bleeding. E. The hematoma may cross dural reflections.B. The hematoma may cross suture lines.Explanation: An epidural hematoma occurs when an artery ruptures and blood collects between the dura and the skull. At suture lines, the dura tightly adheres to the calvarium. Since an epidural hematoma does not cross these tight junctions occur, it is not seen crossing suture lines.
118Question 2: Which of the following is NOT true concerning cerebral contusion? A. Cerebral contusion often occurs when the brain impacts an osseous ridge or dural fold. B. On CT, cerebral contusions appear as ill-defined hypodense areas. C. On CT, cerebral contusions are often mixed with foci of hemorrhage. D. After 1 to 2 days, coalescence of petechial hemorrhages into a rounded hematoma is common.E. The occipital, temporal, and parietal lobes are the most common locations of cerebral contusion.Explanation: Cerebral contusions most commonly occur in the anterior tip, the inferior surface and sylvian region of the temporal lobe, the anterior pole and inferior surface of the frontal lobe, the dorsolateral midbrain, and the inferior cerebellum.
119Question 3: Which of the following is NOT true concerning diffuse axonal injury? A. Diffuse axonal injury can present with a normal head CT. B. Diffuse axonal injury is the most common cause of morbidity in CNS trauma. C. Diffuse axonal injury is often associated with intraventricular hemorrhage.E. Acceleration, deceleration, and rotational forces cause diffuse axonal injury.D. On CT, diffuse axonal injury appears as ill-defined areas of high density or hemorrhage.Explanation: On CT, diffuse axonal injury occurs as ill-defined areas of low density. The often accompanying hemorrhage appears as bright spots of high density.
120B. Subarachnoid hemorrhage over cerebral convexities. Question 4: Given the following CT, the most likely diagnosis is: A. Diffuse axonal injury.C. Subdural hematoma. D. Hypertensive hemorrhage in the occipital lobe.B. Subarachnoid hemorrhage over cerebral convexities.Explanation: The arrows in the image indicate the areas of high density that correspond to hemorrhage over cerebral convexities.
121C. Glioblastoma multiforme Question 5: The CT on the top, taken prior to contrast administration and the CT on the bottom, taken after contrast administration, show: A. Epidural hematoma. B. Subarachnoid hemorrhage. D. Subdural empyema.C. Glioblastoma multiformeExplanation: The gliobastoma in the right frontal lobe is outlined by arrows in the images here. Notice the enhancement of the edges of the tumor upon contrast administration (bottom), and how the tumor crosses into the left hemisphere.
122Question 6: Given the following head CT, the most likely diagnosis is: B. Epidural hematoma. C. Chronic subdural hematoma. D. Subarachnoid hemorrhage.A. Acute subdural hematoma.Explanation: The arrowheads outline the high-density, crescent-shaped hematoma overlying the right cerebral hemisphere. Note the hypodense region (red arrow) within the high-density hematoma (blue arrows), which may indicate active bleeding. The high density and active bleeding are indicative of an acute subdural hematoma.
123C. Diffuse axonal injury. Question 7: Given the following head CT, the most likely diagnosis is: A. Hypertensive hemorrhage in the frontal lobe. B. Subarachnoid hemorrhage over cerebral convexities.D. Intracranial tumors.C. Diffuse axonal injury.Explanation: The arrows indicate the hemorrhage in the subcortical white matter of the left frontal lobe. Such hemorrhage often accompanies diffuse axonal injury, the direct evidence of which (ill-defined areas of low density) is not always apparent on CT. (see question 3)
124D. Diffuse axonal injury Question 8: Which of the following is NOT shown in this CT? A. Intraventricular hemorrhage B. Subarachnoid hemorrhage C. Diffuse hypodensityD. Diffuse axonal injuryExplanation: The intraventricular hemorrhage is clearly visible as the high density blood in the left lateral ventricle. The area of high density in the left cerebral hemisphere is the location of the subarachnoid hemorrhage (red arrow). Areas of low density around the subarachnoid hemorrhage are diffuse hypodensity as a result of edema (blue arrow).
125A. CT can be rapidly performed. Question 9: Which of the following is NOT an advantage to performing a CT scan for stroke?A. CT can be rapidly performed.C. CT allows easy exclusion of hemorrhage. D. CT allows the assessment of parenchymal damage.B. It is always possible to distinguish between old and new infarcts.Explanation: It is not always easy to distinguish between old and new infarcts. MR is a better in this regard. Other disadvantages of CT are its current lack of functional information and limited ability to evaluate the vertebrobasilar system.
126Question 10: Which of the following is NOT true concerning CT? A. CT is the imaging modality of choice for the detectiing of subarachnoid hemorrhage.B. Small subarachnoid bleeds may be inapparent. C. On CT, subarachnoid hemorrhage appears as high density within sulci and CSF cisterns.D. CT becomes more sensitive days to weeks after the acute phase of a subarachnoid hemorrhage.Explanation: Blood is reabsorbed from CSF days to weeks after the acute phase of a subarachnoid hemorrhage. As this occurs, the hemorrhage becomes isodense to the brain. Thus, CT becomes less sensitive in detecting subarchnoid hemorrhage.