When should a head computed tomography (CT) scan be performed in pediatric patients according to the Canadian head CT guidelines?

Canadian Head CT Guidelines for Pediatric Patients

Head CT in pediatric trauma should be performed based on validated clinical decision rules that stratify risk, with the PECARN criteria being the most widely validated and sensitive tool for identifying children who can safely avoid CT scanning. 1

Risk Stratification Framework

The approach to pediatric head CT differs by age group, with distinct criteria for children under 2 years versus those 2 years and older:

Children Under 2 Years of Age

Children meeting all "very low risk" PECARN criteria can safely forgo CT imaging with <0.02% risk of clinically important traumatic brain injury. 2 These criteria include:

• Glasgow Coma Scale (GCS) of 15 2
• Normal mental status 2
• No palpable skull fracture 2
• No nonfrontal scalp hematoma 2
• Loss of consciousness ≤5 seconds 2
• No severe mechanism of injury 2
• Acting normally per parents 2

CT is strongly indicated for high-risk features including:

• GCS of 14 or other altered mental status (4.4% risk of clinically important injury) 2
• Palpable skull fracture 2

Intermediate-risk children (GCS 15 with normal mental status but loss of consciousness >5 seconds, severe mechanism, or not acting normally per parent) have approximately 0.9% risk and may be managed with either CT or careful observation. 2

Children 2 Years and Older

CT is recommended for high-risk factors including:

• GCS of 14 or other altered mental status (4.3% risk of clinically important traumatic brain injury) 2
• Signs of basilar skull fracture (4.3% risk) 2

CT should be considered for intermediate-risk factors including:

• Vomiting 2
• Severe headache 2
• Neurological symptoms such as visual disturbance 2

Very low-risk children (GCS 15, normal mental status, no basilar skull fracture signs, no vomiting, no severe injury mechanism, no severe headache) should not undergo CT. 2

Important Clinical Context

Observation as Alternative to Immediate CT

Clinical observation before CT decision-making effectively reduces unnecessary radiation exposure without delaying diagnosis of significant traumatic brain injury. 1 Every additional hour of emergency department observation is associated with decreased CT utilization across all risk groups, with all significant injuries still identified. 1

Special Populations Requiring Different Approach

The PECARN clinical decision rules specifically excluded children with suspected abuse and should NOT be applied to these patients. 1, 3 For suspected abusive head trauma:

• Either noncontrast CT or MRI is recommended in any child with suspicion of abusive head trauma 1
• Physicians should have a low threshold for neuroimaging in children <6 months given high incidence of occult brain injury 1
• CT is preferred for unstable patients and those with acute trauma and concern for skull fracture 1

Radiation Risk Considerations

Pediatric patients have increased susceptibility to radiation-induced cancers due to actively dividing cells and longer life expectancy, making strict adherence to dose optimization essential. 3 The pediatric brain is particularly sensitive with larger proportion of actively dividing cells. 3 However, the magnitude of risk from a single head CT study is expected to be very low. 3

Facilities must implement pediatric-specific, reduced-dose CT protocols following the ALARA principle. 1, 3 Technical innovations including adaptive statistical iterative reconstruction have achieved 20% radiation dose reductions. 3

Technical Imaging Specifications

Initial head CT for acute trauma should be performed without intravenous contrast because contrast may obscure subtle hemorrhages. 1 Dedicated pediatric head CT parameters with protocols tailored to patient size should always be used. 1

Multiplanar and 3D-reconstructed CT images increase sensitivity for fractures and small hemorrhages and should ideally be performed. 1

Critical Pitfalls to Avoid

• Never apply the Ottawa CT Head Rule to pediatric patients under 16 years of age—this rule was validated only for adults and has absolute contraindication for children. 4
• Do not obtain CT in very low-risk patients meeting all PECARN criteria—this exposes them to unnecessary radiation without clinical benefit. 2, 3
• Avoid routine "pan-scan" whole-body CT in pediatric trauma patients—use selective region-specific scanning based on clinical prediction models instead. 1, 3
• Do not use skull radiographs for traumatic brain injury evaluation—they miss up to 50% of intracranial injuries. 2