Dr Krishna Kiran MD,DNB,FRCRRadiologist

Calicut

Tools available.What is normal.?What to use and when..?

Available tools.Xray skull

NeurosonogramCT brainMRI brainPET CTDigital subtraction angiography.

AP view Towne `s view

Skull radiographs

AP view Towne `s view

Sagittal suture

Lambdoid suture

Coronal suture

Lateral

Lateral

Lambdoid suture

Coronal suture

Skull Xrays have few indications.No longer used in trauma.

Neurosonogram

Refers to performance of high

frequency ultrasound across

open fontanelle.

Critical in premature babies.

Used mainly for intraventricular

hemorrhage , hydrocephalus ,

HIE assessment.

Neurosonogram For Against Bedside.Economical.No radiation.Equals or better than CT in

good operators

Possible only in first year.Operator dependent.Usually needs CT

confirmation.

CT brain

Employs X rays and computer to deliver cross sectional images of body.

CT brainFor Against Established technique to

detect brain pathology.Widely available.Less cost.Very good to detect

hemorrhage , fracture etc.

Radiation risk.Not as sensitive as MRI.Not good in assessing White

matter disease.

What is radiation risk..?For a cumulative dose of 50-60 mGy (milli Gray a unit

of radiation absorbed dose) there is 3 fold increase in

brain tumors when performing brain CT , 3 fold

increase in leukemia when red marrow is exposed.

What is radiation risk..?In a typical CT scanner , 2-3 head scans will give a

dose of 50-60 mGy to a child.

Berrington de González A, Mahesh M, Kim KP, Bhargavan M, Lewis R, Mettler F, Land C. Projected cancer risks from computed tomographic scans performed in the United States in 2007. Archives of Internal Medicine 2009; 169: 2071-7.

Why is radiation risk important to children..?Children live longer than adults , hence more time

for radiation effects to manifest. It takes 20-40 years

for cancer to manifest after exposure.

If not careful , children may get same dose as adults.

Children more sensitive to radiation.

Also increased risk of radiation induced cataract.

However remember that CT study can be lifesaving many times.

Hence use judiciously.

MRI

What`s so special about MRI..

Its unique multiecho technique gives tremendous insight to living body in health and disease.

Two men watching a statue in a candle. Just imagine there were multiple candles at different angles would not picture be clear..? This is what MRI does.

What is T1 sequence..

T1 refers to time taken for return of net magnetization.

A T1 weighted image is produced by this property.

Practically , we need to identify T1 weighted image.

Remember FLUID IS BLACK on T1.

T1 image of brain

What is T2 sequence..T2 image of brain

T2 refers to loss of transverse magnetization.

A T2 weighted image is produced by using this property.

Practically we need to know FLUID IS BRIGHT on T2

More than 100 different sequences are there FLAIR ,STIR,CISS,SPACE,GRE,SSSFE , FSE,TSE………..

MRI BRAINFor Against Gold standard in detection

of pathology.No radiation.Images can be obtained in all

planes.

Children need sedation.Not widely available.

MRI slices through brain , compared to an expert slicing through bread cutting uniform pieces !.

Let us see some clinical situations…

Case 1 9 year old with history of road traffic accident one

hour back.Child is vomiting , also complains of headache.Investigation of choice EMERGENCY CT BRAIN

Epidural hematomaSkull fracture

Contd..Neurosurgeon decided not to operate.Child was managed conservatively , they also took 2

more CT brain scans.Child was discharged with request to do brain

imaging after 6 weeks.Which is the appropriate test..?MRI brain is the more appropriate test here.

CT brain is the first modality in trauma.It depicts hemorrhage and skull fractures well.MRI is second line investigation in head trauma.

Fractures may be missed on MRI.

Case 25 year old child with headache , early morning

projectile vomiting.You suspect an SOL.MRI with contrast is the ideal test.

Posterior fossa midline tumor , most consistent with medulloblastoma. Also see hydrocephalus.

Case 37 year old boy with deterioration in school

performance , vision deterioration , reduced hearing.? Leukodystrophy.MRI brain is the investigation of choice.

Flair

Abnormality in posterior white matter. Typical 3 zone appearance on contrast scan. MRI features consistent with adrenoleukodystrophy.

Case 410 year old child with chronic headache.Clinical examination- normal. Fundus- normal.Parents insist on SCAN..In this setting where clinical suspicion is low , both

MRI or CT may be used.

Case 5First episode of right focal seizures followed by

generalized tonic clonic seizures.Again MRI is the modality of choice

Contrast

MRI shows nodular enhancing lesion , probably tuberculoma.

How accurate is MRI ..?Depending upon signal , enhancement pattern MRI

gives approximate diagnosis.One needs to be watchful , plan for histopathology

confirmation when warranted.

How does cysticercus look on MRI..?

Demonstration of scolex in a cyst is considered key in cysticercosis.

Case 6Premature baby in NICU , you sudden notice sudden

drop in hematocrit , bulging fontanelle.You are not inclined to shift baby out of NICU. Bedside NEUROSONOGRAM is the ideal test.

Coronal Sagittal

Coronal Sagittal

Intraventricular hemorrhage in right lateral ventricle

Coronal Sagittal

Normal neurosonogram

Conclusion Appropriate use of imaging is essential.

CT brain can be lifesaving., particularly in trauma. But

use it sparingly. Remember radiation effects.

MRI brain is modality of choice in most chronic

pediatric neuro conditions.

Less than 1 year think of neurosonogram.