Ct & mri of central nervous system
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Ct & mri of central nervous system

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    Ct & mri of central nervous system Ct & mri of central nervous system Presentation Transcript

    • CT&MRI of Central nervous system Dept. Radiology, the 2nd affiliated hospital, Sun Yat-Sen University Huang Sui Qiao
    • CT Scanning
      • Plain CT
      • Contrast CT
    • CT scanner
    • CT characteristics of pictures
      • CT value : depending on different organ and tissues to X ray.
      • call HU ( Hounsfield Unit ) .
      Bone Soft tissue Water Fat Air
    • Magnetic Resonance Imaging
    • MRI----conventional sequences
      • SE sequence ( spin echo )
        • T1-weighted,T1-WI
        • TR: 200-800ms TE:15-30ms
        • T2-weighted,T2-WI
        • TR:1500-2000ms TE:60-150ms
        • Proton Density,N(H) )
        • TR:1500-2500ms TE:15-30ms
      • IR sequence ( inversion recovery sequence )
        • TR ( short ) TE ( short ) TI ( short )
    • MR signal characteristics
      • SE sequences :
        • T1-WI: highist signal on fat tissue ,better for showing anatomical structures
        • T2-WI: highist signal in liquid, better for detecting lesions
        • N ( H ) Density,N(H): for characteristics of lesions
      • GRE sequence : flip angle , fast scan
      • IR sequence : separation between of fat and liquid
    • MR signal charateristics T2WI T1WI
    • MR signal charateristics Fat supression Liquid supression
    • Normal anatomical structure of head on CT Brain stem; cerebellum;suprasellar cistern; lateral sulcus; quadrigeminal cistern; lateral ventricle; basilar ganglion
    • Normal anatomical structure of head on CT Gray matter; white matter; cortex; frontal lobe; occipital lobe; parietal lobe; temporal lobe; internal capsule ; thalamus; falx
    • Normal anatomical structure of head on MRI
    • T2WI
    • T1WI
    • Flair sequence
    • T2WI(coronal section )
    • T1WI ( sagittal section ) Corpus callosum; optic chiasm; pituitary gland; medulla oblongata
    • Intracranial tumors
      • ٭ primary (80%) : originating from cranial bone,
      • cranial meninges, brain tissues,
      • vessels, cranial nerves, pituitary
      • gland, etc.
      • glioma (50%) , mingioma(14%) , pituitary
      • tumor (11%) , acoustic neuroma(7%)
      • ٭ secondary (20%) : metastasis , involved by tumor
      • from near structures.
    • The types of intracranial tumors
      • Intraaxial brain tumors :
      • 1.glioma(astrocytoma and oligodendroglioma)
      • 2.ependymoma
      • 3.medulloblastoma
      • 4.hemangioblastoma
      • 5.papilloma choroideum
      • 6.metastases
    • The types of intracranial tumors
      • Extraaxial brain tumors
      • 1.meningioma
      • 2.craniopharyngioma
      • 3.pituitary tumor
      • 4.nerve sheath tumors-acoustic
      • schwannoma
      • 5.epidermorid cyst, dermoid cyst and
      • hamartomas
    • The rule for diagnosis of intracranial tumors
      • There are or not a tumor
      • The position of a tumor : intraaxial or
      • extraaxial
      • The type of a tumor
    • 一、 Direct signs 1. tumor or occupying lesion. 2. abnormal density or signal. 3. enhancement in different degree on enhanced scan. CT and MRI Signs for diagnosis of intracranial tumors 、
    • 二、 indirect signs 1. shift of near structures 2. edema in brain tissue near tumor 3. intratumoral bleed 4. intratumoral calcification 5. bone changes
    • astrocytoma lower grading of astrocytoma , grading I or II .
      • Often in adult (20~40 years ) -- more occult in cerebral hemisphere , grading II , solid
      • child– less see , more in cerebellum , grading I, cyst
    • astrocytoma
      • CT : low or slightly low density lesion , no or
      • slight occupying effect , no or slight
      • enhancement.
      • MR : Isointensity on T1WI , unclear border ,
      • high or slightly high signal intensity on T2WI
      • no or slight occupying effect , no or slight
      • enhancement.
    • Grading I astrocytoma Plain CT
    • Grading I astrocytoma T 1 WI T 2 WI
    • Grading I astrocytoma T2W Gd+ Gd+ MR:39547
    • astrocytoma high grading ( grading III or IV)
      • Fast growing
      • Occur in any age
    • Imaging appearances of high grading astrocytoma
      • Obvious occupying effects ,infiltrating growing with unclear margin , growing across lobe and hemisphere.
      • Necrosis, cyst , bleed.
      • Obvious brain edema around tumor.
      • Obvious uneven or ring-like enhancement.
    • Grading IV astrocytoma MR:39985 T2W T1W Gd+
    • Grading IV astrocytoma MR:39985 T2W Gd+ T2W Gd+
    • MR : 53847 Grading IV astrocytoma
    • Brain metastasis
      • Old age
      • Single or multiple
      • Multiple appearances on CT or MR, but often shown in nodule
      • Heterogeneous density or signal, central necrosis with lower density or signal on T1WI.
      • Ring-like or even enhancement
      • Obviously finger-like peritumoral edema
    • Multiple metastases
    • Metastasis from lung cancer uncontrast contrast
    • Metastasis from lung cancer uncontrast contrast
    • Lung cancer and brain metastases MR:39491
    • The types of intracranial tumors
      • Extraaxial brain tumors
      • 1.meningioma
      • 2.craniopharyngioma
      • 3.pituitary tumor
      • 4.nerve sheath tumors-acoustic
      • schwannoma
      • 5.epidermorid cyst, dermoid cyst and
      • hamartomas
    • meningioma
      • Most common nanglial intracranial tumor.
      • Mostly affect 40-70 adults.
      • Extraaxial mass attaching dura matter,about 90% occult on suppratentorium of cerebellum, few of them can occult in ventricles
    • Imaging of meningioma
      • Round or hemishere mass occur mostly in convexity of brain , especially sagittal sinus.
      • Mass with clear margin which was encysted with cerebral spinal fluid and/or vessels.
      • Iso- or slightly high density on plain CT and low signal on T1WI, iso- or slightly high signal on T2WI, which was enhanced obviously and evenly.
      • A broad thickened dural-based margin which was called “tail sign” .
      • Edema may be not or obvious.
      • Local bone changes including destruction, thin or thickness.
    • Left parietal meningioma Plain CT Contrast CT Round high density mass Obviously and evenly enhanced
    • Right parietal meningioma Plain T1WI Contrast T1WI
    • T2WI AND contrast T1WI
    • meningioma T2WI T1WI Gd-T1W
    • Acoustic schwannoma
      • Benign tumor, occur mostly at middle age people, approximately 7﹪~8﹪ of all primary intracranial neoplasms.
      • Ovoid or tubular tumors may occur in the internal auditory canal and cerebellopontine angle cistern .
      • Tumor may be part of solid and cystic .
      • On Plain CT, solid part of tumor was iso-density ,and cystic part was low density.
      • Iso-intensity or low signal intensity were seen in solid or cystic part of tumor on T1WI, but high or very high signal intensity on T2WI,.
      • Obvious enhancement was seen on solid tumor.
      • Enlargement of internal auditory canal.
    • Left acoustic schwannoma
    • Left acoustic schwannoma T2WI T1WI Contrast T1WI
    • Left acoustic schwannoma
    • Right acoustic schwannoma T1WI Contrast T1WI
    • Right acoustic schwannoma Contrast T1WI
    • CT and MRI diagnosis of brain vascular diseases
      • Bleed in high pressure patients
      • Intracranial aneurysm
      • Cerebral infarction
    • Brain bleed (hemorrhage)
      • Causes : high blood pressure, vascular malformation and tumor
      • Stage : acute, subacute, chronic
    • CT&MRI appearances of hemorrhage at different stage
      • CT was more sensitive for acute hemorrhage
      • CT - high density, CT value about 60 - 80Hu
      • MRI - iso-intensity on T1WI, slightly low or low
      • intensity on T2WI.
      • Subacute hemorrhage
      • CT - iso- or slightly high density.
      • MRI - iso- or high signal intensity on T1WI, iso- or
      • slightly high signal intensity on T2WI.
      • chronic hemorrhage
      • CT - iso- or low density
      • MRI - high signal intensity both on T1WI/T2WI.
    • Acute hemorrhage ( high density on CT )
    • Acute hemorrhage ( high density on CT )
    • Subacute hemorrhage Density lower than acute stage with unclear margin
    • acute/subacute hemorrhage acute subacute T2WI T1WI
    • Change from acute to subacute stage ( CT low density hemorrhage ) CT after bleed CT 2W latter MRI 2W latter
    • Chronic intracranial hemorrhage
    • Intracranial aneurysm
      • causes : congenital ; acquired (often high blood pressure )
      • type : according to morphology (saccular ,fusiform), size and location etc .
    • Aneurysm
      • ● Incidence : 0.2~1%.
      • ● Distribution of age: mid-old age(30~60years),seldon in youth.
      • ● morphology : saccular ( 95% ) ,fusiform .
      • ● size : <0.5cm small; 0.5~1.5cm middle;1.5~2.5 large
      • ; >2.5 huge
      • ● position : internal carotid A--41.3%; anterior communicating A--24.4%; middle cerebral A—20.8%; anterior cerebral A—9%; vertebral-basilar A--4.5% 。
    • CT appearances
      • Showing aneurysm directly, filing defect in large one ( thrombus )
      • Subarachnoid hemorrhage in ruptured aneurysm.
    • MR appearance
      • 1. aneurysm without thrombus: round or oval homogeneous
      • very low signal lesion both on T1 and T2WI.
      • 2. aneurysm with thrombus : heterogeneous both on T1
      • and T2WI , high signal in some area.
      • 3. enhanced scan : may be heterogeneously enhanced
    •  
    • Aneurysm at left internal carotid A
    • Aneurysm at left internal carotid A
    • T1WI-contrast T1WI-contrast
    • Aneurysm at left internal carotid A
    • Aneurysm at left middle cerebral A
    • CT&MRI diagnosis of cerebral infarction
    • CT appearances of cerebral infarction
      • Acute stage - onset within 4 - 6h.
      • normal/slightly low density and narrowing of sulcus on infarction area because of edema; low density after 12 - 24h , but no any abnormal finding within 24h.
      • Subacute stage - within 1 week , typical CT
      • appearance.
      • Low density on infarction area with mass effect.
      • After 2 - 3 weeks , iso- or slightly low density with unclear margin, enhancement at border area in contrast scan.
      • Chronic stage - even low density with clear margin. Atrophy of local brain.
    • MR appearances of cerebral infarction
      • High signal intensity at Acute , subacute and chronic stage on T2WI because of increment of fluid at infarction.
      • Iso-intensity at acute stage , iso- or slightly low intensity at subacte stage, low intensity at chronic stage on T1WI.
      • Flair and DWI sequences are more sensitive for detecting acute infarction.
    • MR:44396 Within 24h After 3 days After 2 weeks Acute cerebral infarction
    • MR:44396 MR&CT appearances of acute cerebral infarction Within 24h after 3 days after 2 weeks
    • MR:44396 MR&CT appearances of acute cerebral infarction T2WI T1WI Flair
    • MR:44396 MR&CT appearances of acute cerebral infarction Flair T1WI T2WI
    • Acute infarction MR : 66335 CT : 122740 M 39 , CT (-)
    • Acute infarction MR : 66335 CT : 122740 M 39 , CT (-)
    • Acute infarction MR : 66335 CT : 122740
    • Acute infarction DWI MR : 66335 CT : 122740
    • Subacute/chronic infarction—T2WI
    • T2WI--Cor
    • Chronic infarction at brain stem and cerebellum—T2WI
    • Chronic infarction at brain stem and cerebellum—T1WI
    • CT&MRI diagnosis of head trauma
    • The types of head trauma
      • 一、 Skull fracture
      • 二、 traumatic cerebral swelling
      • 三、 brain contusions
      • 四、 Intracranial bleed of trauma
      • ( 一 ) Epidural hematoma
      • ( 二 ) Subdural hematoma
      • ( 三 ) Subarachnoid hemorrhage
      • ( 四 ) intracerebral hematoma
    • CT&MR diagnosis of cranial trauma
      • Epidural hematoma :
      • ٭ direct violence on skull
      • ٭ skull fracture and deformation
      • ٭ direct laceration or tearing of meningeal arteries
      • ٭ local hematoma ,not across cranial suture
      • ٭ shape of duple convex mirror
    • CT appearances
      • ٭ local duple convex mirror with high density, CT value at 40~100Hu.
      • ٭ there are or not mass effect according the size of hematoma which compress gyri , ventricles. Midline is shifted to contralateral side.
      • ٭ the density of hematoma decrease during the time, become isodesity at about 2 weeks (subacute stage) and low density at about 1 month (chronic stage) .
    • acute epidural hematoma at left frontal lobe
    • acute epidural hematoma at right frontal lobe
    • Acute epidural hematoma at temporal-parietal lobe
    • MR appearances
      • ٭ shape of hematoma is seen like CT
      • ٭ signal intensity of hematoma varies greatly depending on times.
      • ٭ at acute stage ( 0~2 days ), iso-intensity on T1WI , low intensity on T2WI.
      • ٭ at subacute stage ( 3~14 days ), becoming high signal intensity from rim to center on T1WI, still low signal intensity at 6~8 days and high signal intensity after 8 day on T2WI.
      • ٭ at chronic stage (14 days later) , high signal intensity on both T1WI and T2WI for quite long times (may be several months)
    • Subacute hematoma at left frontal lobe
    • Subacute hematoma at left frontal lobe
    • Subacute hematoma at left frontal lobe
    • Subdural hematoma
      • ٭ location: supratentorial convexity.
      • ٭ caused by stretching and tearing of bridging veins.
      • ٭ hematoma is located between dura mater and arachnoid. Often quite large extent , across cranial suture.
      • ٭ CT appearances : crescentic high density. Dividing into acute, subacte and chronic stages . Density changes of hematoma at different stages similar to epidural hematoma.
      • ٭ MR appearances : shape of hematoma seen as CT , signal changes of hematoma similar to epidural hematoma at different stages.
    • Acute subdural hematoma at right frontal-temporal area
    • Subacute subdural hematoma at left frontal-temporal area
    • Subacute subdural hematoma at left frontal-temporal area
    • Subacute subdural hematoma at left frontal-temporal area
    • Subacute subdural hematoma at left frontal-temporal area
    • Chronic subdural hematoma at left frontal lobe
    • CT&MR diagnosis of brain contusion
      • ٭ Often involve the temporal and frontal lobe. Temporal lobe lesions tend to lie just above the petrous bone or posterior to the greater sphenoid wing. Frontal lobe lesions occur just above the cribriform plate, orbit, planum sphnoidale, and lesser sphenoid wing.
      • ٭ CT appearances : high density of hemorrhagic foci (vary in size ) scattered throughout the larger nonhemorrhagic
      • zone or lower density area (edema). May be or may not be mass effect.
    • Contusion at frontal lobe
    • Contusion at both sides of frontal base
    • Contusion at temporal lobe
    • MR appearances
      • ٭ MR is more sensitive than CT to find small contusion because of easy to find edema caused by contusion.
      • ٭ hemorrhagic foci appear petechia or multiple confluent regions with high signal intensity.
      • ٭ easy to find contusion at brain stem.
    • Contusion and epidural hemorrhage at both temporal lobe and frontal lobe
    • Contusion and epidural hemorrhage at both temporal lobe and frontal lobe
    • Multiple contusions at both sides of frontal and temporal lobes
    • Multiple contusions at both sides of frontal and temporal lobes
    • THANK YOU