Pediatric Emergency Imaging

Pediatric Imaging Principles - Little Bodies, Special Rules

• ALARA: "As Low As Reasonably Achievable" radiation. Children are radiosensitive.
  • 📌 Image Gently campaign.
• Modality Hierarchy:
  • USG first (abdomen, pelvis): No radiation.
  • X-ray: Bones, initial chest.
  • CT: Trauma, complex cases; use low-dose protocols.
  • MRI: Soft tissue, neuro; often needs sedation.
• Sedation: Key for motion-free MRI/CT. Consider age, procedure (e.g., chloral hydrate).
• Contrast: Weight-based. Iodinated (CT): 1-2 mL/kg. Gadolinium (MRI): lower NSF risk.

⭐ USG is the workhorse in pediatric emergency imaging: safe, accessible, no ionizing radiation.

Pediatric Trauma - Spotting Hidden Harm

• Non-Accidental Injury (NAI):
  • Skeletal survey: Suspected NAI, unexplained fractures (#s), esp. < 2 yrs.
  • Key findings:
    • Metaphyseal "corner"/bucket-handle #s.
    • Posterior rib #s (squeezing).
    • Skull #s: multiple, bilateral, depressed, crossing sutures, different ages.
    • Spinous process, sternal, scapular #s.
    • Multiple #s in varied healing stages.

  ⭐ Metaphyseal "corner" or "bucket-handle" fractures are highly specific for NAI.

• Common Accidental Fractures:
  • Torus (buckle) #: Cortex bulges.
  • Greenstick #: Incomplete #, cortex bent.
• Salter-Harris Classification (Epiphyseal Plate Injuries): 📌 SALTR
  • Type I (Slipped): Through physis.
  • Type II (Above): Physis + Metaphysis (Most common).
  • Type III (Lower): Physis + Epiphysis.
  • Type IV (Through): Metaphysis + Physis + Epiphysis.
  • Type V (Ruined): Crush injury to physis (Poor prognosis).

• Head Trauma:
  • Initial imaging: CT for moderate/severe trauma.
  • PECARN rule helps decide CT use in low-risk children to reduce radiation.

Acute Abdomen Imaging - Gut Instincts Visualized

Key pediatric abdominal emergencies and their imaging hallmarks:

• Intussusception
  • USG: "Target sign" (bowel-within-bowel), "pseudo-kidney sign". Best initial test.
  • Air/Contrast Enema: Diagnostic & therapeutic; "meniscus sign" or "coiled spring" appearance.
• Appendicitis
  • USG: Non-compressible, blind-ended tubular structure >6mm diameter; "target sign" (transverse); periappendiceal fluid/fat stranding.
  • CT: If USG equivocal or suspicion of perforation/abscess.
• Malrotation with Volvulus
  • UGI Series (Gold Standard): "Corkscrew sign" of duodenum/jejunum. Abnormal duodenojejunal (DJ) flexure position.
  • USG: "Whirlpool sign" (SMV rotates around SMA). Inverted SMA/SMV relationship.
• Hypertrophic Pyloric Stenosis (HPS)
  • USG: Pyloric muscle thickness >3-4mm, channel length >14-16mm. "Olive sign" (palpable), "cervix sign" (USG).
• Necrotizing Enterocolitis (NEC)
  • Abdominal X-ray (Supine & Decubitus): Pneumatosis intestinalis (pathognomonic), portal venous gas, pneumoperitoneum (Rigler's sign, football sign).

⭐ Target sign (doughnut sign) on USG is pathognomonic for intussusception.

Imaging Acute RLQ Pain in Children:

Chest & Neuro Emergencies - Breathless & Brainy

• Respiratory Emergencies:
  • Pneumonia: X-ray patterns (lobar, interstitial, round) aid diagnosis.
  • Foreign Body Aspiration (FBA):
    • Inspiratory X-ray: Unilateral hyperinflation, atelectasis.
    • Expiratory/Decubitus X-ray: Air trapping, mediastinal shift to normal side.
  • Croup (Laryngotracheobronchitis):
    • X-ray (AP neck): Steeple sign (subglottic narrowing).
  • Epiglottitis: ⚠️ Medical emergency!
    • X-ray (lateral neck): Thumb sign (swollen epiglottis). Caution: Clinical diagnosis prioritized; imaging if airway stable.
    • 
• Neurological Emergencies:
  • Non-traumatic Seizures: CT/MRI if focal, prolonged, new-onset (>6mo, afebrile), abnormal exam, or post-traumatic.
  • Hydrocephalus:
    • Infants: USG (ventricular size, IVH screen).
    • Older: CT/MRI (detailed anatomy, cause).
  • Hypoxic-Ischemic Injury (HIE): MRI shows patterns (basal ganglia/thalamus-term; watershed; periventricular leukomalacia-preterm).

⭐ Steeple sign (Croup, AP) for subglottic narrowing vs. Thumb sign (Epiglottitis, Lateral) for swollen epiglottis.

High‑Yield Points - ⚡ Biggest Takeaways

• NAI: Suspect with multiple fractures (varied healing), posterior rib, or metaphyseal corner fractures.
• Intussusception: Target sign (USG); air/contrast enema is diagnostic & therapeutic.
• Pyloric Stenosis: USG: thickened pylorus (>3mm), elongated canal (>14mm).
• Malrotation/Volvulus: Upper GI series (corkscrew) is gold standard; USG: whirlpool sign.
• Appendicitis: Graded compression USG (appendix >6mm, non-compressible) is key.
• NEC: X-ray: pneumatosis intestinalis, portal venous gas.
• Epiglottitis: Thumbprint sign (X-ray); Croup: Steeple sign (X-ray).