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 .
Dr. Francis Neuffer
Department of Radiology
CT, MR, Ultrasound, Angiography
Multiple sectional images are obtained from a preliminary
scout image showing the beginning and end of the scan.
IV IODINE CONTRAST
Selected images from CT scans posterior fossa level
Hydrogen protons align in magnetic field
No ionizing radiation
SCANS ARE DESIGNED TO SHOW SPECIFIC TISSUE
AND SPECIFIC PATHOLOGY
Thetissuesignalvariesdependingonthetype of scanperformed.
Flow is seen at the common carotid bifurcation on contrast
X- ray arteriography and B-mode ultrasound.
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.
Images of vessels at the Circle of Willis
MR Angiogram- venous injection
Images can be obtained at MR by injecting gadolinium and imaging rapidly as the agent circulates through the arterial circuit.
1 DAY POST
2 DAY POST
Note increase in edema
Anterior Cerebral Artery
Middle Cerebral Artery
Posterior Cerebral Artery
The different vascular distributions of cerebral territories are
represented on color coded CT diagrams
The supra sellar cisterniswhiteduetothebloodmixedwiththe CSF.
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.
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
Acute Blood is dense on
Non contrast CT
IS AN IMPORTANT CAUSE OF SPONTANEOUS CORTICAL- SUBCORTICAL INTRACRANIAL HEMORRHAGE (ICH) IN THE NORMOTENSIVE ELDERLY.
Chao C P et al. Radiographics 2006;26:1517-1531
Withreperfusiononinfarctareathereishemorrhageintoinfarctzonewith local masseffect and midlineshift.
GOAL FOR IMAGING
Thrombolytic therapy to salvage ischemic brain at the border of the infarct zone (ischemic penumbra).
Who benefits and how to select?
3-6 hour window
Risk of hemorrhagic conversionSTROKE INTERVENTION
Typically 3hrs sinceonsetisthelimitforinitiation of venousthrombolytictherapy. With arterial therapythewindow of action can be extended . Therisk of bleedingintotheinfarctzonewithreperfusionis a complicationthat can worsen prognosis.
Note acute occlusion of Rt. MCA circulation and edema in Rt. hemisphere on CT. Comparison of the normal Lt. side is shown.
Catheter is advanced for thrombolysis of the MCA thrombus with improved perfusion on last injection of contrast.
?Abnormality on CT
Questionable lesion on CT in a Rt. periventricular location.
diffusion weighted better show
the acute evolving ischemic infarction
Venous bleeding from “bridging veins” which connect cerebral cortex to Dural sinuses
Concave inner margin
Older patient –atrophy enlarged subdural space
Pediatric patient –shaken baby/child abuse
small subdural space can lead to herniation
Over time thebloodbreaksdown and decreases in density.
Hit head on RT. With superficial scalp hematoma
Subdural hematoma on LT due to tearing of bridging veins with
Deceleration with fall.
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.
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
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
AIR IN FRONTAL SINUS
FRONTAL LOBE CONTUSION
NORMAL CHORIOD PLEXUS
Air extends intracranially from fracture of the skull or through the sinuses.
Spread of sinus infection to the epidural space can occur.
JC virus reactivated-fatal-rapid
Patients with altered immunity are subject to many atypical infections.
Toxoplasmosis is rarely seen in immunocompetent patients.
Metastatic disease- 50/50 -Primary malignancy
The ring enhancing lesion is the site of abnormal blood/brain barrier.
The low density center often is necrotic tissue.
CT WITH CONTRAST
Axial section MR
with gadolineum contrast
DURAL BASED LESIONS
CAN BE LARGE.
INCREASED DENSITY is due to calcium and not bleeding
impinge on optic chiasm
Conduction vs sensory
Weber and Rinne test
INTERNAL AUDITORY MEATUS LESION
Bilateral lesions associated with Neurofibromatosis 2.
CHRONIC NEUROLOGIC SYMPTOMS
Alzheimers, Multi infarct, Hydrocephalus
With Alzheimer’s disease little is seen on MR and CT except atrophy as a nonspecific finding.
NORMAL PRESSURE HYDROCEPHALUS
CHRONIC NEUROLOGIC SYMPTOMS
DUE TO DEMYELINAZATION
? MULTIPLE SCLEROSIS
Focal white matter lesions show increased water due to breakdown on myelin at sites of involvement.
THERE’S STILL HOPE
Ultrasound- vascular screening