Materials covered in lecture

Report
NEURO IMAGING
Dr. Francis Neuffer
Department of
Radiology
USC-SOM
GOALS AND OBJECTIVES
• Review major imaging modalities of neuro imaging.
CT, MR, Ultrasound, Angiography
• Review classic disease states of vascular, traumatic, infectious
and neoplastic diseases.
DIGITAL SCOUT FILM SHOWING BEGINNING AND END
OF CT SCAN.
Multiple sectional images are obtained from a preliminary
scout image showing the beginning and end of the scan.
iV Contrast enhancementNON-CONTRAST
STUDY
IV IODINE CONTRAST
STUDY
ANATOMY
Selected images from CT scans posterior fossa level
Basilar
Artery
Supracellar
Cistern
Temporal
Horn lateral
ventricle
4th
Ventricle
Pons
Cerebellum
ANATOMY
Thalamic level
3rd
ventricle
Sylvian
fissure
Atria
Lateral
Ventricle
Thalamus
Falx cerebri
ANATOMY
Internal capsule level
Anterior Horn
Lateral ventricle
Caudate Nucleus
Internal
capsule
Lentiform
nucleus
Occipital
Lobe
ANATOMY
Ventricle level
Anterior Horn
Lateral ventricle
Posteror
Horn Lateral
ventricle
ANATOMY
Lateral ventricle level
Frontal
lobe
Body lateral
ventricle
Parietal
lobe
Occipital
lobe
Falx cerebri
ANATOMY
Supraventricular level
Gyrus
Centrum
Semiovale
Sulcus
Superior
Sagittal Sinus
MAGNETIC RESONANCE
• Hydrogen protons align in
magnetic field
• Radio frequency(RF)
excitation and
transmission
• No ionizing radiation
MR SIGNAL
T1 SCAN
T2 SCAN
SCANS ARE DESIGNED TO SHOW SPECIFIC TISSUE
AND SPECIFIC PATHOLOGY
VARIOUS MRI SEQUENCES
T1
FLAIR (edema)
The tissue signal
varies
depending on
the type of scan
performed.
T2 (CSF/edema)
Diffusion
NORMAL
CEREBRAL ARTERIOGRAM
NORMAL
ULTRASOUND
Flow is seen at the common carotid bifurcation on contrast
X- ray arteriography and B-mode ultrasound.
CAROTID ARTERY
Color Doppler
The vessel lumen can be imaged with ultrasound and the velocity of the flow can be measured.
A stenotic lesion will show acceleration of flow through the narrowed lumen.
Catheter injection of
RT common carotid artery
ACA
MCA
ECA
ICA
CCA
•
•
•
•
•
CCA common carotid A.
ICA internal carotid A.
ECA external carotid A.
MCA middle cerebral A.
ACA anterior cerebral A.
VASCULAR ANATOMY
Images of vessels at the Circle of Willis
ACA
MCA
MR VASCULAR ANATOMY
Anterior cerebral
Middle
cerebral
Basilar
artery
ECA
ACA
MCA
Carotid
bulb
ICA
Vertebral
artery
CCA
ICA
MR Angiogram- venous injection
Images can be obtained at MR by injecting gadolinium and imaging rapidly as the agent circulates through the
arterial circuit.
WHO ARE THE PATIENTS ?
• VASCULAR ISCHEMIA
• TRAUMA
• INFECTIOUS WORKUP
• MALIGNANCY WORKUP
CT SCANNING
as initial sorting
•
Ischemia
– Global
–
Focal
Hemorrhage
–
–
–
–
Hypertensive hemorrhage
Amyloid angiopathy
Hemorrhagic infarction
Subarachnoid hemorhage
FOCAL DEFICIT OF 24 HRS
• ACUTE CVA
85% ISCHEMIC
15% HEMORRAGHIC
• TREATMENT DIFFERENCE
ANTICOAGULATION FOR ISCHEMIC CVA
STENOSIS
NORMAL
CT OF ISCHEMIC STROKE
1 DAY POST
2 DAY POST
Note increase in edema
LACUNAR INFARCT
Small vessel = lenticulostriate vessel
MCA proximal branch
basal ganglia-thalamic
VASCULAR DISTRIBUTIONS
Anterior Cerebral Artery
Middle Cerebral Artery
Posterior Cerebral Artery
The different vascular distributions of cerebral territories are
represented on color coded CT diagrams
CT SCANNING
as initial sorting
Hemorrhage
–
–
–
–
Hypertensive hemorrhage
Amyloid angiopathy
Hemorrhagic infarction
Subarachnoid hemorhage
SUBARACHNOID
HEMORHAGE
Increased density
Normal
The supra sellar cistern is white due to the blood mixed with the CSF.
SUBARACHNOID HEMORRHAGE
• Blood in the subarachnoid space
– Between the Pia & Arachnoid
– CT – acute blood, increased density
– Rupture of cerebral aneurysm
• “Worst Headache of Life”
• Location: basal cisterns, sylvian fissure, cortical sulci.
CAROTID ANEURYSM
Associated with Polycystic Renal disease
And Marfans Syndrome
Aneurysms are often at
vascular branch points and
show relative deficit of media
there which contributes to
vessel wall weakness
INTRACEREBRAL HEMORHAGE
HYPERTENSIVE EVENTS
Acute Blood is dense on
Non contrast CT
Pontine Hemorrhage
Thalamic Hemorrhage
CEREBRAL AMYLOID ANGIOPATHY
(CAA)
IS AN IMPORTANT CAUSE OF SPONTANEOUS CORTICALSUBCORTICAL INTRACRANIAL HEMORRHAGE (ICH) IN THE
NORMOTENSIVE ELDERLY.
Chao C P et al. Radiographics 2006;26:1517-1531
Hemorragic infarction—delayed several days
With reperfusion on infarct area there is hemorrhage into infarct
zone with local mass effect and midline shift.
CT SCANNING
as initial sorting
•
Ischemia
Hemorrhage
–
–
–
–
Hypertensive hemorrhage
Amyloid angiopathy
Hemorrhagic infarction
Subarachnoid hemorhage
GOAL FOR IMAGING
Comparison of infarct
zone and ischemic zone
to identify treatment candidates
STROKE INTERVENTION
• Thrombolytic therapy to salvage ischemic brain at
the border of the infarct zone (ischemic penumbra).
• Who benefits and how to select?
STROKE INTERVENTION
• Thrombolytic therapy
3-6 hour window
• Risk of hemorrhagic conversion
Typically 3hrs since onset is the limit for initiation of venous thrombolytic therapy. With arterial
therapy the window of action can be extended . The risk of bleeding into the infarct zone with
reperfusion is a complication that can worsen prognosis.
Lt
Rt
Note acute occlusion of Rt. MCA circulation and edema in Rt. hemisphere on CT.
Comparison of the normal Lt. side is shown.
catheter
Catheter is advanced for thrombolysis of the MCA
thrombus with improved perfusion on last injection of
contrast.
CT vs. MR
? Abnormality on CT
Questionable lesion on CT in a Rt. periventricular location.
Compared to CT--MR scans with T1, T2, and
diffusion weighted better show
the acute evolving ischemic infarction
T1
T2
Diffusion
MR vs. CT
IN EARLY CVA
MR LIMITATIONS
•
COMPLEX MR SIGNAL OF HEMORRHAGE
RELATED TO HEMAGLOBIN—Fe EFFECTS
•
UNSTABLE PATIENT-PATIENT MOTION
MORE A PROBLEM IN MR (LONGER SCAN TIME)
•
CT READILY VISUALIZES BLOOD PRODUCTS
•
ACCESS- CT IS AVAILABLE FOR ER PATIENTS
CT SCANNING
as initial sorting
•
Ischemia
– Global
–
Focal
Hemorrhage
–
–
–
–
Hypertensive hemorrhage
Amyloid angiopathy
Hemorrhagic infarction
Subarachnoid hemorhage
WHO ARE THE PATIENTS?
• HEAD TRAUMA
SUBDURAL HEMATOMA
• Venous bleeding from “bridging veins” which connect
cerebral cortex to Dural sinuses
• Concave inner margin
– Older patient –atrophy enlarged subdural space
unstable gait–falls
– Pediatric patient –shaken baby/child abuse
small subdural space can lead to herniation
SUBDURAL HEMATOMA
(ACUTE)
Over time the blood breaks down and decreases in density.
SUBDURAL HEMATOMA
Hit head on RT. With superficial scalp hematoma
Subdural hematoma on LT due to tearing of bridging veins with
Deceleration with fall.
FRACTURE
EPIDURAL
HEMATOMA
Cause: laceration of meningeal artery/vein adjacent to inner table.
Lucid interval post trauma –later cns injury due to mass effect
Epidural hematomas are more focal than subdurals since
the blood is more confined by the periosteum of the skull.
MIDDLE MENINGEAL ARTERY
SKULL BASE
FRACTURE
Can lead to cerebral spinal fluid leak and
risk of meningitis
The purple ecchymosis behind the ear is
called Battle sign described as a clinical
finding
“RACCOON EYES”
Periorbital ecchymosis is another sign of a basal skull fracture. Blood
tracks along the periosteum and can collect in soft tissues of the orbital lid.
CSF rhinorhea can occur with fractures extending through cribriform plate
CT HEAD TRAUMA
AIR IN FRONTAL SINUS
FRONTAL LOBE CONTUSION
NORMAL CHORIOD PLEXUS
CALCIFICATIONS
TRAUMATIC PNEUMOCEPHALUS
Air extends intracranially from fracture of the skull or through the sinuses.
INTRACERBRAL PRESSURE
HERNIATION
• Tonsillar - brainstem - cardiopulmonary arrest.
• Falcine - anterior cingulate gyrus –ACA infarct.
• Uncus- temporal lobe-- 3rd nerve
WHO ARE THE PATIENTS?
• CNS INFECTION
MENINGITIS
bacterial / viral
•
•
•
•
Little role for imaging-can delay treatment
Lumbar puncture and gram stain
Meningococcal Bacterial can be fatal
Headache, Stiff neck, Fever, Photophobia
SINUSITIS
AND
EPIDURAL ABSCESS
Spread of sinus infection to the epidural space can occur.
AIDS PATIENTS
• TOXOPLASMOSIS --ring enhancing lesions
•
•
•
Atrophy -- HIV viral effect
PML -- progressive multifocal leukodystrophy
JC virus reactivated-fatal-rapid
HIV AND TOXOPLASMOSIS
ring enhancing lesions on CT
noncontrast
contrast
Patients with altered immunity are subject to many atypical infections.
Toxoplasmosis is rarely seen in immunocompetent patients.
WHO ARE THE PATIENTS?
• CNS MALIGNANCY
• Metastatic disease- 50/50 -Primary malignancy
TUMORS
• Primary = Metastatic
•
Lung, Breast, Renal
• Adult- Supratentorial primary tumors
• Pediatric- Infratentorial primary tumors
METASTATIC LESIONS
HISTORY / MULTIPLE
enhance with contrast
The ring enhancing lesion is the site of
abnormal blood/brain barrier.
The low density center often is necrotic
tissue.
CT WITH CONTRAST
ADULTS
Glioblastoma Multiforme
• Malignant astrocytoma-supratentorial
• Can cross midline -corpus callosum
• Butterfly
Coronal section
GBM
Axial section MR
with gadolineum contrast
MENINGIOMA-benign
DURAL BASED LESIONS
CAN BE LARGE.
INCREASED DENSITY is due to
calcium and not bleeding
TUMORS
• Pediatric- Infratentorial primary tumors
PILOCYSTIC ASTROCYTOMA
•
•
•
•
•
Pediatric
Benign
Cystic with nodule
Posterior fossa
Cerebellum
MEDULLOBLASTOMA
• Pediatric-malignant-PNET
• Post fossa -cerebellum
• Spread via CSF
WHO ARE THE PATIENTS?
• VISUAL SYMPTOMS
Bitemporal hemianopsia
• PITUITARY LESIONS• impinge on optic chiasm
SKULL
MR- BRAIN
SELLA
NORMAL
PITUITARY
NORMAL
PITUITARY
ADENOMA
CRANIOPHARYNGIOMA
• Rathke’s pouch - grow from mouth to
between anterior and posterior pituitary
• Bitemporal hemianopsia
• Pediatric patient
• Calcify-Benign
WHO ARE THE PATIENTS?
• HEARING LOSS
• Conduction vs sensory
• Weber and Rinne test
SCHWANNOMA
INTERNAL AUDITORY MEATUS LESION
MR SCANS
WITH GADOLINIUM
WITHOUT GADOLINIUM
Bilateral lesions associated with Neurofibromatosis 2.
WHO ARE THE PATIENTS?
• CHRONIC NEUROLOGIC SYMPTOMS
• DEMENTIA
• Alzheimers, Multi infarct, Hydrocephalus
NORMAL
ATROPHY
With Alzheimer’s disease little is seen on MR and CT except atrophy as a nonspecific finding.
Coronal scans
NORMAL PRESSURE HYDROCEPHALUS
Dllated ventricles
NORMAL
NPH
NORMAL PRESSURE
HYDROCEPHALUS
•
•
•
•
•
CSF not absorbed by arachnoid granulations
Ventricles dilate
Stretch fibers around ventricles - corona radiata
Incontinence, Gate disturbance and Dementia
LP/Shunt improves symptoms
WHO ARE THE PATIENTS?
• CHRONIC NEUROLOGIC SYMPTOMS
• DEMYELINATING DISEASE
ABNORMAL WATER SIGNAL IN THE
CEREBRAL WHITE MATTER
NORMAL
DUE TO DEMYELINAZATION
? MULTIPLE SCLEROSIS
Focal white matter lesions show increased water due to breakdown on myelin at sites of involvement.
DEMYLINATION
MULTIPLE SCLEROSIS
•
•
•
•
•
•
Autoimmune- northern latitudes
Young adult- femaleBlurred vision –optic nerve
Internuclear ophthalmoplegia - CN 3 and 6
Sensory deficit
Autonomic dysfunction- bladder/bowel
IF YOU FEEL LOST
THERE’S STILL HOPE
CT -acute hemorrhage
MR- chronic
Ultrasound- vascular screening
Angiography- intervention

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