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PEDIATRIC NEURO-RADIOLOGYESSENTIALS
Guided by Dr. N. bajaj
Dr. jyoti prajapati
INTRODUCTION
• 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 correct diagnosis.
MODALITIES
• Plain Film
• CT
• US
• MRI
• Interventional– Angiography
– Myelography
– Biopsy
• Nuclear Medicine-SPECT,PET SCAN,PET CT
PLAIN RADIOGRAPHS• 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 management.
• Intracranial calcification, suture separation
Use of x ray in Neuro-radiology
• Intracranial calcification
• Raised ICT
• intracranial tumors
• Head trauma
The radiological signs of raised intracranial pressure
• 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 informative)
Suture separation
Sellar erosionNormal sella
Increased convolutional markings
SIGNS OF INTRACRANIAL TUMOR
• Intracranial calcification
• Skull erosion
• Hyperostosis
• Abnormal vascular markings
• Penial displacement
Causes of intracranial calcification• 1. Neoplasms• Craniopharyngioma
• Glioma
• Meningioma
• Ependymoma
• Papilloma of the choroid plexus
• Pinealoma
• Chordoma
• Dermoid, epidermoid, and teratoma
• Hamartoma
• Lipoma
• Metastasis (rarely)
2. Vascular
• Atheroma
• Aneurysm
• Angioma
• Subdural haematoma
• Intracranial haematoma
3. Infections and infestations
• Toxoplasmosis• Cytomegalic inclusion body disease• Herpes• Rubella• Tuberculosis• Pyogenic abscess• Cysticercosis• Hydatid cyst• Porogonimus abscesses• Trichinosis• Torulosis• Coccidioides
INTRACRANIAL CALCIFICATION PATTERN
• Infection – TORCH Toxoplasmosis often scattered, irregular, flaky
• Rubella is massive or punctate
• CMV often curvilinear and paraventricular
• Herpes - involves entire brain
toxoplasmosis
Calcified basal exudate above the sella in a patient withhealed tuberculous meningitis (arrowheads).
Cysticercosis. There are multiple small calcified lesions2-3 mm in diameter (arrowheads).
sturge weber syndrome
Tuberous sclerosis
Metastasis(multiple lytic lesion)
Bilateral hypertrophy of the middle meningeal vascular markings in a patient with a large angiomatous malformation.
Computerized TomographyCT
• 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 patients.
• Provides fine details of the bony structures.
• Can be used in emergency and in pt with pacemaker
Indication
• Subarachnoid heamorrage
• Fractures
• Headtrauma
• 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 insideMake 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 sliceCheck the soft tissues of skullCheck the bony calvariumCheck the cortical sulciCheck the basal gangliaCheck the ventricular size/shape/position
Normal CT of brain
Ventricles are normal sized,
the grey versus white
distinction
is clear.
Midline is straight.
Sulci are symmetrical on both
sides.
Skull is intact with no
scalp edema.
NEONATAL BRAIN• The neonatal brain In CT images the density
of the brain is dependent on the stage of maturation
• 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 sulci.
• 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.
1 day 1 year 2 years
mri
3D CT
CT Terminology
• 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
NORMAL CT
• Contrast within the image varies from white (high attenuation) to black (low attenuation) with the type of tissue within the voxel:– Bone(white)
– Soft tissue(white)• Gray matter
• White matter
– Water(csf)-(black)
– Fat(black)
– Air(black)
• Pathological processes are identified by alterations in anatomy and attenuation.
• Pathological processes typically increase the water content in tissue it makes them hypodense.
• 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 the voxel.
• 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 neighboring protons.
• T1 weighted images - cortical anatomy
• Proton density weighted images - brainstem and basal ganglia
• T2 weighted images - Ventricles, cisterns and vasculature, edema
T1 weighting
• Tissue contrast•dense bone - dark (few hydrogen protons)•air - dark (few hydrogen protons)•water (CSF) – dark( black)•brain - anatomical–Gray matter - gray–White matter - whiter
T2 WIGHTING• dense bone - dark (few hydrogen
protons)• air - dark (few hydrogen protons)• water (CSF) – bright(hyperdense)• brain
–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 showingnormal 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.
MRI
T1 T2
MRI
• When protons are placed in a magnetic field they become capable of receiving and transmitting radiofrequency(rf) electromagnetic waves.
• 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.
MRI indication• Neoplasm- asessment of size,extent & effect
on normal brain.
• developmental anomalies of the brain.
• Neurodegenerative/ demylinating disorders
• vascular anomalies of the head (aneurysm )
• stroke
• trauma patients (after 24 hr).
Cont.
• disease in the pituitary gland.
• Inflammatory & infectious deseases (most sensitive for detection for demylinating plaque)
• Headache
• Chronic encephalopathies
• Cyst & hydrocephalous
• Myelopathy & degenerative disorders of spinal cord
• MRI is less sensitive than CT in detection subarachnoid heamorrage ,bony abnormalities, calcification, and can not be performed in pt with pacemaker & mettalicprosthesis
Normal MRI
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.
Normal tissue
MR-T1 MR-T2 CTenhancement
infarct dark bright Dark subacute
bleed Bright bright Bright no
tumor Dark bright dark Yes
MS plaque Dark Bright dark acute
Abnormal tissue
CT MRI
Time taken for
complete scan:
Usually completed within 5
minutes
Scanning typically run
for about 30 -40min
Details of bony
structures:
Provides good details
about bony structures
Less detailed compared
to CT scan
Effects on the
body:
More less
Principle used for
emaging
X-ray Uses large external field,RF pulse
Details of soft
tissues:
Less tissue contrast Much higher detail in
the soft tissues
Radiation
exposure:
Moderate to high radiation None
COST medium high
d/b gray & white
matter
good excelent
awailability Easily awailable less
CT ANGIOGRAPHY
INDICATION- arteriovenous malformation
• Old cases of stroke
• Aneurism
• Cerebral thromboembolism
• Vascular tumor
Normal carotid angiogram
Arteriovenous malformation
Vertebral arteriogram showing dissecting aneurysm of a posterior
interior cerebellar artery (MR study).
Aneurism in MR angiography
Cantrst enhanced MR Angiography
CT angio of giant unruptured MCA aneurysm
PET SCAN• 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 for cancers.
PET- SCAN
• 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
• Parkinsonism
• Dementia
• Neurodegenerative disoder
• Brain & spinal cord tumor
• Neuroendocrine tumors
Acadeny of medicine singapur
• Epilepsy• Between seizures, a PET scan displays
decreased metabolism in the area of the seizure and increased metabolism in the same area during a seizure.
CRANIAL USG
• CUS helps in demonstration of cerebral pathologies in premature and sick newborn babies like hemorrhage, ischemia and ventricular dilatation.
• 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 or infarct.
• In the sagittal images check the caudothalamic grooves for signs of hemorrhage, check the midline for the corpus callosum and the cerebellum
Pattern of injury in TF-USGThe 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 necrosis).
• b. Focal ischemic lesion may be evident as echodensity in an area of vascular distribution associated with loss of pulsations in the affected vessel.
• 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 nicuthough 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.
Coronal Midline sagittal
Angled para sagittal
Tangential parasaggital
frontal Ant horn of 3rd
ventricle
trigone
Occipital
Cranial usg
Sagital view
Cranial usg coronal view frontal lobe
Early periventricularleucomalacia:ultrasonography shows increased
echogenicity in B/L frontal and left parietal region
Grading of neonatal intracranial haemorrhage
• 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
thecaudothalamic groove– 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
hydrocephalus
Cranial Usg in metabolic disorder
Coronal view
Hemiparetic CP
BRAIN ABSCES
necrotic, supprative center encapsulated by a peripheral rim of hyperemic granulation tissue.
It is normally located at the gray matter / white matter junction, and is surrounded by edema.
The granulation tissue shows ring enhancement with contrast.
Cerebral abscesses from endocarditis
DEMYLINATING DISORDERS
MS-axial T2-weighted image. Plaques are mainly periventricular, oval shaped with a major transverse axis, hyperintense with respect to normal parenchymaRING ENHANCEMENT FOLLOWINF GADOLLIUM INJECTION
INFARCTION
INFECTION & INFLAMATION
• The lesion is poorly defined, usually hypodense at CT and on MRI it is hypointense in T1 and hyperintense in T2.
• MeningitisBoth CT and MRI may show leptomeningeal enhancement and associated cortical or brain involvement.
abscess formation in a patient with bacterial meningitis. This contrast-enhanced, axial T1-weighted magnetic resonance image shows a right frontal parenchymal low intensity (edema), leptomeningitis(arrowheads), and a lentiform-shaped subdural empyema(arrows).
Bacterial meningitis. Axial Nonenhanced CT
scan shows mild ventriculomegaly and
sulcal effacement
Microbacteria and fungi produce abscesses and granulomas with or without meningeal involvement;
both CT and MRI are sensitive in demonstrating the lesions, particularly following contrast injection.
TBM may show enhancing liesion after contrast injection.
Parasitic infections
• 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 encountered.
Hole with dot on CT
SWISS CHEES
MRI
TBM
• On CT scan, the most common finding in cranial tuberculous
• meningitis (TBM) is obliteration of the basal cisterns by isodense or mildly hyperdenseexudate.
• After the administration of contrast medium, there is dense homogeneous enhancement of the basal meninges.
TBM
• Contrast-enhanced computed tomography scan shows dense enhancement of
• the thickened inflamed basal meninges.
MILIARY TB
VentriculitisBRAIN STEM CEREBRITIS
Granulomatoustuberculousmeningitis,
ventriculitis, andspinal
arachnoiditis
Caseatingtuberculosis
granuloma involving the left
thalamus and causing obstructive
hydrocephalus in
Viral infections
• 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.
Herpes encephalitis
Bi-temporal distribution is typical.
Thought to occur by re-activation
of herpes virus much like “cold sores”
Except through different nerve
Distribution.
HSV ENCEPHALITIS
CONGENITAL ABNORMALITEIS
DANDY WALKER SYNDROME
PORENCEPHALY
Neurocutaneous syndrome
Tuberous sclerosis MRI
Sturge weber syndrome
Brain tumors
• 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% of patients.
• Low-grade gliomas typically are nonenhancinglesions 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.
Brain tumor
T2
Stroke
• Intra parenchymal
• Subarachnoid heamorrhage
• Subdural heamatoma
• Epidural heamatoma
• Lacunar infarcts
• Ventricular bleed
MCA Stroke“Dense MCA”
Case 2
Epidural heamotoma
Subarachnoid heamorrhage
Subarachnoid Hemorrhage
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).
Intraparenchymal bleed into ventricles
Intraventricular bleed
Radiation risk
• Relative values of CT exam exposure
– Background radiation is 3 mSv/year
• Water, food, air, solar
• In Denver (altitude 5280 ft.) 10 mSv/year
– CXR = 0.1 mSv
– CT head = 2 mSv
– CT Chest = 8 mSv
– CT Abdomen and Pelvis = 20 mSv-The equivalent of 200 CXR
Thanks for listening
References;-nelson
suttons radiology
neuroradiology –robert
caffeys
pediatric radiology donnelly
various websites