Radiology · Year 4 · from Radiology
Case 3: Radiation Safety - Pediatric Imaging Considerations
Patient Demographics
- Age: 6 years
- Sex: Male
Chief Complaint
Right lower quadrant abdominal pain
Presenting Symptoms
The child presents with 18 hours of periumbilical pain that has migrated to the right lower quadrant. He has had one episode of vomiting and decreased appetite. His mother reports he has been walking hunched over and is reluctant to jump or climb stairs.
Physical Exam Findings
- Vital Signs: Temp 38.2C, HR 110 bpm, RR 22/min
- Abdomen: Moderate tenderness in the right lower quadrant, voluntary guarding, positive Rovsing sign, mild rebound tenderness
- General: Child appears uncomfortable but not toxic
Imaging Findings and Interpretation
Imaging Selection Rationale: Following ALARA principles and Image Gently guidelines, ultrasound is selected as the first-line imaging modality for this pediatric patient with suspected appendicitis because:
- Avoids ionizing radiation exposure
- High sensitivity (88%) and specificity (94%) for appendicitis in children
- Can visualize alternative diagnoses
- Readily available and does not require sedation
Ultrasound Findings: Graded compression ultrasound of the right lower quadrant demonstrates:
- Dilated, non-compressible appendix measuring 9 mm in diameter (abnormal >6 mm)
- Target sign appearance on transverse imaging
- Hyperemia of appendiceal wall on color Doppler
- Echogenic periappendiceal fat stranding
- Small amount of free fluid adjacent to the appendix
- No appendicolith identified
Diagnosis Confidence: The ultrasound findings are diagnostic for acute appendicitis with high confidence. CT is not needed for confirmation, thereby avoiding approximately 3-4 mSv of radiation exposure.
Diagnosis
Acute uncomplicated appendicitis diagnosed by ultrasound
Management
- Pediatric surgery consultation for appendectomy
- NPO status and IV fluid resuscitation
- IV antibiotics (ceftriaxone and metronidazole) per institutional protocol
- Laparoscopic appendectomy performed within 24 hours
- Histopathology confirmed acute suppurative appendicitis
Radiological Image
Image Description: Ultrasound demonstrating acute appendicitis with a dilated, non-compressible appendix displaying the target sign (concentric rings representing the layers of the inflamed appendiceal wall). This radiation-free imaging modality is preferred for pediatric patients.
Source: Wikimedia Commons - "Acute appendicitis on ultrasound" URL: https://commons.wikimedia.org/wiki/File:Ultrasonography_of_appendicitis.jpg License: Creative Commons Attribution-Share Alike 3.0 Unported
Learning Points
- Contrast-Induced Nephropathy Prevention: Patients with eGFR <45 mL/min/1.73m2 require careful risk stratification. Prevention includes hydration, using minimal contrast volume, and considering alternative non-contrast imaging when possible.
- MRI Safety Screening: All patients must be screened for ferromagnetic implants before MRI. Non-MRI-conditional pacemakers and ICDs are absolute contraindications. CT myelography provides an alternative for spine imaging.
- ALARA Principle in Pediatrics: Children have greater radiosensitivity and longer remaining lifespan for radiation-induced effects. Ultrasound should be the first-line modality for suspected appendicitis in pediatric patients per Image Gently guidelines.
- Modality Selection: Choosing the appropriate imaging modality requires balancing diagnostic accuracy, radiation exposure, contrast risks, and patient-specific factors. The right test for the right patient at the right time.