Radiology Flashcards
How do CT scanners damage cells
The radiation from them creates ions and free radicals which have enough energy to break the covalent bonds between DNA strands.
The cell will try and repair this but may be unsuccessful leading to a mutation which is passed onto daughter cells
Why are children more at risk from CT scanners than adults
Children are more sensitive to radiation as they are still growing and have a higher cell production rate
They also have a longer life expectancy than adults, resulting in a larger window of opportunity for expressing radiation damage
May end up receiving a higher dose if the machine is not adjusted to a smaller body
How can we minimise CT radiation exposure in children
Only perform CTs when absolutely necessary
Use non-radiating methods like US or MRI where possible
Adjust machine to minimise dose - child size, organ system and target area
Exposure to ionising radiation as a child increases the risk of brain tumours - true or false
True
Approximately 3 times the risk
Gliomas, schwannomas, meningioma
Exposure to ionising radiation as a child increases the risk of leukaemia - true or false
True
Which neuroimaging procedures are considered safe in children
Cranial US
EEG
MRI (unless they have metal implants or need GA)
What is the main contraindication of X-ray in children
Must consider pregnancy in girls post menarche
Otherwise a relatively low dose of radiation
List conditions which could cause altered consciousness in a child
Sepsis Raised ICP Trauma Hypoglycemia Post-convulsive state DKA Shock Meningitis or encephalitis
What is the first line neuroimaging technique in children with altered consciousness
CT head
Especially in acute setting
Which conditions require neuroimaging in children
New-onset blackouts
History or signs of head trauma / haemorrhage
Acute clinical brain injuries
Raised Intracranial pressure
Intracranial abscess
Altered consciousness of unknown origin
What is the investigation of choice for seizures when EEG/clinical presentation is not diagnostic
MRI scan
MRI scans should be carried out in which children presenting with seizure
Diagnosed with epilepsy before 2 years of age
With a history/EEG suggestive of focal onset
In whom seizures persist following first-line therapy
Which underlying patholgies causing a seizure may be picked up on MRI
Brain haemorrhage - usually a few days post event (consider NAI)
Infection - meningeal enhancement may be seen in meningitis
Tumours - can cause focal seizures
How can CT scans be used in the investigation of seizures
In acute setting it can be used to determine if a seizure has been caused by an acute neurological lesion or illness
Can be used to find underlying pathology if MRI unavailable or contraindicated
CT scans can be useful if the child or young person would require general anaesthetic or sedation for an MRI but not for CT.
What is the primary investigation for head trauma in children
CT
MRI can be added after if more information about the injury is required
Which children should be sent for a CT head within 1hr of presentation
Suspicion of NAI
Post-traumatic seizure, but no history of epilepsy
GCS <14, or for children under 1 year GCS (paediatric) < 15 · At 2 hours after the injury GCS < 15
Suspected open or depressed skull injury or tense fontanelle
Any sign of basal skull fracture (haemotympanum ‘panda’ eyes, cerebrospinal fluid leakage from the ear or nose, Battle’s sign). ·
Focal neurological deficit ·
For children under 1 year, presence of bruise, swelling or laceration of more than 5 cm on the head
Children who do not require an urgent CT within 1hr but have a risk factor present should be monitored for how long
At least 4 hours post head injury
Then considered for CT or discharge depending on how they are
There are a second set of risk factors following head injury and if a child has more than one, they need a CT - what are they
Witnessed loss of consciousness > 5 minutes
Abnormal drowsiness
3 or more discrete episodes of vomiting
Dangerous mechanism of injury (high-speed road traffic accident either as a pedestrian, cyclist or vehicle occupant, fall from height of > 3 metres, high speed injury from an object
Amnesia (antegrade or retrograde) lasting > 5 minutes
Should be sent for CT within an hour of the risk factors being identified
When a child is being monitored post-head injury, which factors would make them eligible for a head CT
If during this observation period they experience further episodes of vomiting or abnormal drowsiness or their GCS drops below 15
What is the one condition that would require a head CT in a child with a head injury even if they didnt have any of the risk factors
If they are on anticoagulant therapy due to hemorrhage risk
All kids on these therapies should get a head CT within 8 hours of injury
When would a child get a skeletal survey
If there was suspected NAI
Which factors can pre-dispose a child to cervical spine injury
Trisomy 21, osteogenesis imperfecta, achondroplasia, and other rheumatological, congenital, metabolic or genetic conditions or previous cervical spine surgery
What are the criteria for X-ray in suspected C-spine injury
Unable safely assess range of movement
(cervical tenderness/intoxication/not alert)
Unable actively rotate neck 45 degrees
GCS 14-15
Dangerous mechanism injury:
What are the criteria for CT in C-spine injuries
Focal peripheral neurological deficit
Paraesthesia in upper or lower limbs
GCS < 14
XR inadequate/shows significant injury
Intubated
What are the screening tests for lower spinal injuries
AP and lateral XR of thoracic and lumbar spine
How might bronchiolitis present on a CXR
Overinflated lungs, otherwise normal
Perihilar haze
Scattered atelectasis
Rarely more diffuse opacification
How might bacterial pneumonia present on a CXR
Fluffy consolidation with air bronchograms
Rounded, lobar or multifocal patterns
Effusion
Pneumatocoele/pneumothorax
Which organisms commonly cause bacteral pneumonia in children
mycoplasma, pneumococcus, staph aureus, haemoph influenzae
How is the orientation of an inhaled foreign body affected by its site
Coronal if supraglottic or oesophageal
Sagittal if tracheal
How does inhaled foreign body present on CXR
Obviously might see the body itself if radioopaque
Lucent lung (black on XR) due to air trapping is common due to ball valve effect
Mediastinum displaces away from the affected side
Pattern exaggerated in expiration
Atelectasis of affected lung is less common
Which fracture patterns are specific to children and adolescents
Buckle fracture
Plastic Bowing
Softer bones tend to bend/bow rather than snap/splinter
Greenstick fracture -incomplete fracture
Growth plate injury
The growth plate or physis can appear like a fracture on XR - true or false
True
It appears as an area of lucency between the epiphysis and metaphysis and may simulate a fracture
Therefore need to know what normal looks like
Why is the growth plate prone to injury
It is the weakest part of the developing bone
How do you grade growth plate injuries
the ‘Salter-Harris’ classification
What is the correct tip position for an endotracheal tube in a neonate
2cm above the carina at about C2/3
How does neonatal pneumothorax present on CXR
Neonatal and infant CXRs are obtained supine, not erect
Pleural air collects anteriorly, rather than superiorly, adjacent to the heart in lateral costophrenic sulci
How does pneumomediastinum present on CXR
Air may outline the heart. thymus and mediastinal vessels
Gas may extend to the neck
What is the correct tip position for a nasogastric tube
In the stomach
If a NG tube cannot be passed in a neonate what might be the issue
Oesophageal atresia
What is the normal course for an umbilical vein catheter
from umbilicus to umbilical vein to left portal vein or ductus venosus to middle/left hepatic veins into IVC - correct tip position is at or just above the right hemidiaphragm
What is the normal course for an umbilical artery catheter
from umbilicus
to R or L internal iliac art
to common iliac artery
then into the aorta -
What is the correct low and high tip position for an umbilical artery catheter
correct low tip position is lower lumbar (L3/4, below renal arteries)
correct high tip position is between D6-10
Why do children produce poor CXR
inadequate inspiration and rotation simulate disease
The thymus is visible on CXR in infants - true or false
True
Visible on CXR up to 2 years age and often massive in neonates
Often has ‘angel wing’ morphology
Can simulate mediastinal mass or lung opacity
Sometimes nodular
List common causes of neonatal respiratory distress
Transient tachpnoea of the newborn (TTN)
Surfactant deficiency (NRDS, HMD)
Pneumonia
Meconium aspiration
How does surfactant deficiency present on CXR
Small volume lungs (Bell shaped thorax)
Diffuse granular opacification, progressing to opaque lungs, with bronchograms
No effusion unless complications arise
Surfactant deficiency can lead to what complications
May develop atelectasis, persistent PDA and CCF, pulmonary haemorrhage, pneumonia
How does transient tachypnoea of the newborn present on CXR
normal or overinflated lungs
interstitial lines and effusions
fluid in fissures
air space opacification
How does meconium aspiration present on CXR
patchy opacities
overinflated lungs due to air trapping
air leaks common - bubbly lungs
atelectasis - collapse
How does neonatal pneumonia present on CXR
patchy opacities
overinflation or atelectasis
When would you suspect neonatal pneumonia
Suspect when term infant with no meconium and patchy CXR changes
In the context of trauma, list potential causes of raised ICP in an infant
intra or extra-axial haemorrhage, or non-haemorrhagic brain parenchymal injury
When in cranial US useful in infants
If they have acute brain injury
It may show the intracranial pathology but can also indirectly assess intra-cranial pressure through Doppler measurement
When should a skeletal survey be performed
When NAI is suspected
Which skeletal injuries should raise suspicion of NAI
Metaphyseal corner fractures
Posterior or lateral rib fractures
Multiple fractures in different healing stages
Sternal, scapular and spinous process fractures
Spinal injuries with no clear history of major trauma
What is the role of imaging in childhood UTIs
Identify structural abnormality that could cause urine stasis and predispose to UTI
Exclude functional vesico-ureteric reflux of potentially infected urine
Quantify renal scarring due to previous UTI
Used in children under 6 months
Older children only if recurrent
Which imaging is used to investigate UTI in children
Renal US
US of other UT components - bladder and urethra
If abnormal may progress to a renogram
Which imaging technique is used to detect renal function and scarring post UTI
DMSA scan
Carried out 4-6 months after UTI as acute focal (reversible) pyelonephritis can simulate scars
