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CPS Statements 2018-2020 > Imaging The Term Neontal Brain > Flashcards

Imaging The Term Neontal Brain Flashcards

1
Q

When is brain imaging indicated in infants?

A 
Neonatal encephalopathy 
Seizures 
Unexplained apnea’s 
Infections
Metabolic disorders 
Birth injuries 
Suspected brain abN
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2
Q

What are the advantages of US

A 
No ionizing radiation 
Portable 
Readily available 
Easily repeated 
Economical 
No special preparation 
Can measure cerebral blood flow
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3
Q

What are the limitations of U/S

A

May not visualise convex surfaces or the posterior fossa well
User dependent

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4
Q

What are the limitations to CT

A

Less likely to detect injuries to deep gray nuclei, brain stem and cerebellum
Less likely to detect strokes
Ionizing radiation required
Poor gray/white matter contrast due to lack of myelination

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5
Q

What does fat and water look like on MRI in

  1. T1 weighted images
  2. T2 weighted images
A
  1. Water = dark, fat = light

2. Water = lighter

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6
Q

What is MRI-DWI

A

Measures motion of water molecules when magnetic gradient is applied

Following cytotoxic oedema there is impaired movement of water molecules leading a diffusion restriction = allows calculation of apparent diffusion coffieicnet

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7
Q

How are the apparent diffusion cofficient maps used

A

Determines site and extent of injury

  • diffusion restricted areas = low ADC
    appear brighter on DWI, appear darker on ADC maps
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8
Q

What biochemical compound metabolism is assessed with MRS

A

N-acetylaspartate (NAA) = decrease with dysfunction/death

Lactate = increase with energy source failures

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9
Q

What are the advatnages to MRI for newborn brain imaging?

A

More sensitivity and specific for detecting brain abN
No ionizing radiation
Better diagnostic accuracy and patient safety
Few contraindications
More availability of MRI compatible equipment
Can help understand extent of injury, and scope of recovery and repair possible

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10
Q

What is neonatal encephalopathy?

A

A clinically defined syndrome of disturbed neurological function in the earliest day of life in the term infant

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11
Q

What are clinical features of NE

A

Apnea
AbN tone and reflexes
Altered consciousness
Seizures

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12
Q

What are causes of NE

A 
HIE
IEM 
Infection
Bilirubin toxicity
Metabolic disturbances 
Cerebral dysgenesis
Stroke
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13
Q

What patterns of injury are seen in HIE

A

Watershed

Basal ganglia/thalami

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14
Q

What are watershed injuries?

A

Affect areas between brain’s major arterial supplies, and deep in sulci leading to cortical edema/necrosis/infarction

Associated with prolonged partial HIE

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15
Q

How does watershed injury look on imaging

A

Day 3-5d MRI: restricted diffusion, lactate peak in watershed regions, T1/2 may be normal

Day 10-14: Maximal injury on T1/T2
- see increased signal intensity on T1 weighed

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16
Q

What are basal ganglia/thalamic injuries?

A

Seen in acute, profound HIE

Injury in the areas with highest metabolic rate and need for energy substrates

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17
Q

How does basal ganglia/thalamic injuries look on imaging

A

Day 3-5d MRI: restricted diffusion with hyper intense signal, lactate peak in regions, T1/2 may be normal OR if severe may see hyper intense signal already on T1

Day 10-14: Maximal injury on T1/T2
- see increased signal intensity on T1 weighed

18
Q

What are typical findings on MRI for basal ganglia/thalamic injuries

A

Higher signal intensity on T1 in basal ganglia (seen early at day 3-5)

Later higher signal intensity in the ventro-lateral nuclei of the thalami

Loss of normal signal intensity in the posterior limb of the internal capsule

19
Q

How many infants have watershed lesions, basal ganglia/thalamic lesions and normal MRI

A

watershed lesions = 52%
basal ganglia/thalamic lesions = 22%
normal MRI = 26%

With a known sentinel event - more have basal nuclei damage

20
Q

What can you see if there’s severe HIE ?

A

Effacement of sulcal markings
Closure of Sylvia fissures
Narrowing of interhemispheric fissures
Compression of anterior horns of lateral ventricles

  • may be seen on CT, MRI, US
21
Q

What type of MRI imaging is most sensitive for acute brain injury in the first 3 days of life

A

DWI

22
Q

When can imaging be done HIE

A
  • MRI + DWI + MRS: day 3-5 to diagnosis, repeat at date 10-14 if not consistent examination or if dx ambiguity
  • U/S - day 1 of life can see significant brain injury, at 24-36 with Doppler can see rebound cerebral blood flow (more so in moderate-severe watershed injuries)
  • CT: 72 +/- 12 hours after suspected insult - can see increasing edema, best sees basal ganglia/thalamic injury or total injury, may underestimate severity of white matter and cerebral cortex injury
23
Q

What brain injury patterns are associated with severe motor and cognitive disability?

A

Basal ganglia/thalamic lesions with abN intensity in the PLIC

(Watershed patterns more CI than motor - predictor of language outcome)

24
Q

What percent of children with moderate basal ganglia/thalamic injury have:

  1. CP
  2. CI (IQ<70)
A
  1. 60-70% (up to 90% with severe)

2. 35%

25
Q

What is the most accurate quantitative biomarker for predicting ND outcome after HIE

A

MRS - deep gray matter lactate and NAA measures
Sensitivity 82%
Specificity 92%

26
Q

When should infants who were cooled for HIE be imaged?

A

Days 4-5, after rewarmed

27
Q

What is the most sensitive modality for neonatal stroke imaging?

A

MRI - can look at vessels and branches

28
Q

What vessel branch is most commonly involved in neonatal stroke

A

left MCA

29
Q

What does a neonatal stroke look like on MRI acutely?

A

T1: loss of grey/white matter differentiation

DWI - hyperintense signal = restricted diffusion in the area of infarction

30
Q

What do you see on MRI at 1-2 mo of age in an infant who had a neonatal stroke?

A

Tissue loss, cyst formation at site of infarction

31
Q

What is the best modality for imaging infants with IEM

A

MRI

32
Q

What can you see on U/S with IEM?

A

Cysts
Calcifications
White matter changes
Structural abN

33
Q

In what IEM disorders is DWI and MRS helpful?

A

MSUD
nonketotic hyperglycinemia
Creatine deficiency

34
Q

In traumatic brain injury what do you see with

  1. U/S
  2. CT
  3. MRI
A
  1. ICH
  2. ICH, bone abN, fractures
  3. Delineates injury, best for parenchymal injury
35
Q

What imaging modality is the best if there’s suspicion for an underlying fracture

A

CT

36
Q

What is the preferred imaging modality in structural brain abN

A

MRI

37
Q

What changes do you see on MRI with bilirubin encephalopathy?

A

Acute: hyperintense signal on T1 in globus pallidus, subthalamic nuclei

Kernicterus: hyperintense signal in T2

38
Q

When should imaging be done with severe hyperbilirubinemia

A

Only if there’s encephalopathy

39
Q

When should an MRI be done in congenital infections

A

Suspected or proven congenital infections
Established CMV infection
AbN ultrasounds

40
Q

MRI is the preferred modality for which causes of neonatal encephalopathy

A 
HIE
Congenital infection
Bilirubin encephalopathy 
Structural brain abN
IEM
Neonatal stroke
41
Q

When is US a useful first imaging modality

A

Hemorrhage, major structural anomalies, calcification

BUT also ways needs to be confirmed with MRI

42
Q

When is CT a useful first imaging modality

A

Urgent situation
MRI is not available
Infant too unstable for MRI
If trauma or suspected skull fracture

CPS Statements 2018-2020 (16 decks)

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