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Guided by Dr. N. bajaj
Dr. jyoti prajapati
• Several complimentary modalities are
currently available in neuroradiology.
• The invention of CT revolutionized imaging of
the brain and the spine.
• MRI further improved our diagnostic ability
and accuracy of CNS disorders.
• Knowledge in neuro-anatomy is essential for
• Plain X-ray is essential modality for initial assessment
of the spine.
• Good display of bony details
• Limited value in evolution of head trauma since it
may not reflect underlying CNS damage.
• Skull radiograph helps in classification of skull
fractures and its extent and therefore further
• Intracranial calcification, suture separation
Use of x ray in Neuro-radiology
• Intracranial calcification
• Raised ICT
• intracranial tumors
• Head trauma
The radiological signs of raised
• I. Suture diastasis-1ST & most important sign in
infants & children
• 2. Sellar erosion- more useful in adults,
chronic raised ICT
• 3. Pineal displacement- in adults
• 4. Increased convolutional markings(not much
Bilateral hypertrophy of the middle meningeal vascular marki
ngs in a patient with a large angiomatous malformation.
• Readily available fast modality for evaluation
of intracranial structures.
• Rapid acquisition of axial images.
• The procedure of choice for evaluation of
patients with head trauma and stroke
• Provides fine details of the bony structures.
• Can be used in emergency and in pt with
• Subarachnoid heamorrage
• Detection of calcification in lision
• Bony spinal stenosis
• When MRI is contraindicated
How to read CT
Overall go from the outside of the skull to the the
Make two passes through the study:
on the first one look at every structure on every
slice from the outside to the inside,
on the second looking at one structure at a time,
look at every slice
Check the soft tissues of skull
Check the bony calvarium
Check the cortical sulci
Check the basal ganglia
Check the ventricular size/shape/position
Normal CT of brain
Ventricles are normal sized,
the grey versus white
Midline is straight.
Sulci are symmetrical on both
Skull is intact with no
• The neonatal brain In CT images the density
of the brain is dependent on the stage of
• At full term the cortex shows convolutions ,the
cerebral sulci are well defined, and the cortex and
white matter are differentiated.
• In premature infants before 30 weeks the brain is
homogeneously low in attenuation with the
cortex appearing as a thin denser ring without
• The sylvian fissures are shallow and wide and the
ventricles appear relatively large.-smaller with
maturity and at term appear as narrow slits.
• During the same period there is progressive
differentiation between white and grey matter,
and the sulci and convolutions become defined.
• Contrast between cortex and medulla increases
as myelination progresses.
• Low attenuation of the white matter is a normal
finding in neonates and usually resolves in the
first 2 or 3 months.
Myelination begins in the brainstem and extends
into the internal capsules and optic radiations by
6 months of life, forceps major and minor by 1
year, and into the gyral convolutions as in the
adult by a year and a half.
• What we can see
– The brain is grey
• White matter is usually dark grey
• Grey matter is usually light grey
• CSF is black
• Things that are brite on CT(hyperdense)
– Bone or calcification
– Contrast agents
– Hemorrhage (Acute)
– Hypercellular masses
– Metallic foreign bodies
• Contrast within the image varies from white (high
attenuation) to black (low attenuation) with the
type of tissue within the voxel:
– Soft tissue(white)
• Gray matter
• White matter
• Pathological processes are identified by
alterations in anatomy and attenuation.
• Pathological processes typically increase the
water content in tissue it makes them
• Intravenous X-ray contrast dye has higher
attenuation than soft tissue.
• Due to the blood brain barrier, injecting X-ray
contrast normally only brightens blood vessels
and tissues without a blood brain barrier like
the choroid plexus.
• Pathological processes typically disturb the
blood brain barrier allowing contrast to enter.
• Proton Density - the pixel intensity is primarily
dependent on the density of protons within
• T1 weighting - pixel brightness dependent on
proton density and weighted towards those
protons that quickly retransmit rf energy
decaying to their baseline unexcited state.
• T2 weighting - pixel brightness dependent on
proton density and the behavior of
• T1 weighted images - cortical anatomy
• Proton density weighted images - brainstem
and basal ganglia
• T2 weighted images - Ventricles, cisterns and
• Tissue contrast
•dense bone - dark (few hydrogen
• air - dark (few hydrogen protons)
•water (CSF) – dark( black)
•brain - anatomical
–Gray matter - gray
–White matter - whiter
• dense bone - dark (few hydrogen
• air - dark (few hydrogen protons)
• water (CSF) – bright(hyperdense)
–Gray matter - gray
–White matter - darker than gray
– Proton Density - intermediate between T1
and T2 signals
• Gray matter - gray
• White matter - darker than gray
axial sections showing
normal anatomy. (A) T,-weighted section shows CSF black and clear
differentiation between white and grey matter. (B-G)
T2-weighted sections in another patient show CSF white and white matter
dark while grey matter remains grey.
• When protons are placed in a magnetic field
they become capable of receiving and
• After receiving rf energy the protons
retransmit rf energy proportional to the
density of protons.
• A pixel within an MRI image represents the
amplitude of the radio frequency signal
coming from the hydrogen nuclei (protons) in
the water and fat within the voxel.
• The timing of the rf pulses and gradients are
altered in different sequences to change the
relative weighting between the proton density
and factors in the microenvironment.
• Neoplasm- asessment of size,extent & effect
on normal brain.
• developmental anomalies of the brain.
• Neurodegenerative/ demylinating disorders
• vascular anomalies of the head (aneurysm )
• trauma patients (after 24 hr).
• disease in the pituitary gland.
• Inflammatory & infectious deseases (most
sensitive for detection for demylinating plaque)
• Chronic encephalopathies
• Cyst & hydrocephalous
• Myelopathy & degenerative disorders of spinal
• MRI is less sensitive than CT in detection
subarachnoid heamorrage ,bony
abnormalities, calcification, and can not be
performed in pt with pacemaker & mettalic
MR-T1 MR-T2 xray-CT
dense bone Dark Dark Bright
Air Dark Dark Dark
Fat Bright Bright Dark
Water Dark Bright Dark
Brain anatomical interm. interm.
MR-T1 MR-T2 CT
infarct dark bright Dark subacute
bleed Bright bright Bright no
tumor Dark bright dark Yes
MS plaque Dark Bright dark acute
Time taken for
Usually completed within 5
Scanning typically run
for about 30 -40min
Details of bony
Provides good details
about bony structures
Less detailed compared
to CT scan
Effects on the
Principle used for
X-ray Uses large external
Details of soft
Less tissue contrast Much higher detail in
the soft tissues
Moderate to high radiation None
COST medium high
d/b gray & white
awailability Easily awailable less
INDICATION- arteriovenous malformation
• Old cases of stroke
• Cerebral thromboembolism
• Vascular tumor
• Positron emission tomography (PET) is a non-invasive
diagnostic imaging procedure that assesses the level of
metabolic activity and perfusion in various organ
systems of the human body.
• A positron camera (tomograph) is used to produce
cross-sectional tomographic images, which are
obtained from positron emitting radioactive tracer
substances (radiopharmaceuticals) such as 2-[F-18]
fluoro-d-glucose (FDG) that are administered
intravenously to the pt.
• Most common indication is for diagnosis and staging
• Positron emission tomography (PET) proving
usefulness in certain aspects of brain deseases
by showing differences in local brain
metabolism but is expensive and is only
available at special centres.
Pet scan indication
• Most common indication is for diagnosis and
staging for cancers.
• Refractory epilepsy
• Neurodegenerative disoder
• Brain & spinal cord tumor
• Neuroendocrine tumors
Acadeny of medicine singapur
• Between seizures, a PET scan displays
decreased metabolism in the area of the
seizure and increased metabolism in the same
area during a seizure.
• CUS helps in demonstration of cerebral
pathologies in premature and sick newborn
babies like hemorrhage, ischemia and
• Also, knowledge of cerebral pathology aids in
predicting neurological outcome according to
the grade of injury.
What are the indications of doing CUS
in a neonate?
• a. Screening CUS in a premature baby
• b. Clinical suspicion of intracranial hemorrhage
• c. Neonatal seizures
• d. Evaluation of large or rapidly enlarging head
• e. Serial follow up of post hemorrhagic hydrocephalus
• f. Hypoxic Ischemic encephalopathy
how to read
In the coronal images, check the size, contents,
and position of the lateral ventricles, looking for
ventricular dilation, intraventricular hemorrhage,
and midline shift.
Look for parenchymal lesions such as hemorrhage
• In the sagittal images check the caudothalamic
grooves for signs of hemorrhage, check the
midline for the corpus callosum and the
Pattern of injury in TF-USG
The following pathologies may be detected by careful ultrasound examination in a
term baby with encephalopathy
• a. Basal ganglia injury may be evident as echodense
(hemorrhagic necrosis) or as echolucent lesions (non-hemorrhagic
• b. Focal ischemic lesion may be evident as
echodensity in an area of vascular distribution
associated with loss of pulsations in the affected
• c. Periventricular Injury, like in a premature baby,
may show up periventricular flare, cyst formation
and progressive ventricular dilatation.
CT MRI are not indicated routinely in nicu
though being extremely sensitive bcs of risk
of radiation and it takes time and baby can
not be monitored during procedure.
Currently, data available from class II studies
do not provide sufficient evidence that
routine MRI should be performed on all very
low birth weight (VLBW) infants for whom
results of screening cranial US are abnormal.
leucomalacia:ultrasonography shows increased
echogenicity in B/L frontal and left parietal
Grading of neonatal intracranial
• Several grading systems have been used for IVH .Commonly used is the one
proposed by Burstein and Papile et.al, which is a sonographic grading system
• grade I
– restricted to subependymal region / germinal matrix which is seen in
– overall good prognosis
• grade II
– extension into normal sized ventricles and typically fills less than 50 % of the
volume of the ventricle
– overall good prognosis
• grade III
– extension into dilated ventricles
– ~ 20 % mortality
• grade IV
– grade III with parenchymal haemorrhage
– 90 % mortality
– it should be noted that it is now thought that grade IV bleeds are not simply
extensions of germinal matrix haemorrhage into adjacent brain, but rather
represent sequelae of venous infarction
B/L grade III germinal matrix and
intraventricular hemorrhage with
Cranial Usg in metabolic disorder
necrotic, supprative center encapsulated by a
peripheral rim of hyperemic granulation
It is normally located at the gray matter / white
matter junction, and is surrounded by edema.
The granulation tissue shows ring enhancement
MS-axial T2-weighted image. Plaques are mainly
periventricular, oval shaped with a major transverse axis,
hyperintense with respect to normal parenchyma
RING ENHANCEMENT FOLLOWINF GADOLLIUM INJECTION
INFECTION & INFLAMATION
• The lesion is poorly defined, usually
hypodense at CT and on MRI it is hypointense
in T1 and hyperintense in T2.
Both CT and MRI may show leptomeningeal
enhancement and associated cortical or brain
abscess formation in a
patient with bacterial
meningitis. This contrast-enhanced,
resonance image shows
a right frontal
(arrowheads), and a
Microbacteria and fungi produce abscesses and
granulomas with or without meningeal
both CT and MRI are sensitive in demonstrating
the lesions, particularly following contrast
TBM may show enhancing liesion after contrast
• The most common parasitic infections are
cysticercosis and echinococcosis.
• In cysticercosis, both intraparenchymal and
meningeal cysts are found which at different
stages may include calcified nodules
• CT clearly demonstrates the calcification;
frequent meningeal enhancement is
• On CT scan, the most common finding in
• meningitis (TBM) is obliteration of the basal
cisterns by isodense or mildly hyperdense
• After the administration of contrast medium,
there is dense homogeneous enhancement of
the basal meninges.
• the thickened
• These may produce minimal changes
at CT and be better seen at MRI with non-specific
T2 hyperintensity both involving the
cortex and the white matter.
• Herpes simplex encephalitis may have
haemorrhagic components demonstrated
by CT and occurs usually bilaterally in specific
locations such as the temporal lobe, the
hippocampus and the insula.
Bi-temporal distribution is typical.
Thought to occur by re-activation
of herpes virus much like “cold sores”
Except through different nerve
• High-grade or malignant gliomas appear as
contrast-enhancing mass lesions, which arise
in white matter and are surrounded by edema
• Multifocal malignant gliomas are seen in ~ 5%
• Low-grade gliomas typically are nonenhancing
lesions that diffusely infiltrate brain tissue and
may involve a large region of brain.
• Low-grade gliomas are usually best
appreciated on T2-weighted MRI scans.
Blood shows white on CT.
Anterior Communicating Artery
aneurysm has burst, flooding the
basal structures under the brain
outside the brain parenchyma, but
will occasionally empty into a
Ventricle as it has on the left here
(see fluid level). Note typical
“bat wing” shape just above the
mid-brain (green arrow).