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Paediatric · Bone/Dosimetry

Paediatric Bone Imaging & Dosimetry

Snapshot

Paediatric bone scintigraphy investigates unexplained limp/pain, suspected osteomyelitis, non-accidental injury, and back pain (with SPECT/CT), interpreted against the child’s active growth plates. Across all paediatric studies, radiation dose is minimised using weight-based administered activity (EANM paediatric dosage card) and ALARA principles.

Growth plates are normally intensely active on bone scans, which must be accounted for. Because children are more radiosensitive and have a longer life expectancy, dose optimisation is paramount.

Growth platesNormal high uptake
ALARADose optimisation
Dosage cardWeight-based activity

When to image

  • Unexplained limp or bone pain with normal radiographs.
  • Suspected osteomyelitis or discitis (with SPECT/CT / cross-referral).
  • Suspected non-accidental injury (adjunct to skeletal survey).
  • Back pain — pars/spondylolysis on SPECT/CT.

How to read it

  • Interpret uptake relative to symmetric physiological growth-plate activity.
  • Asymmetric or focal juxta-physeal uptake is a clue to pathology.
  • Use SPECT/CT to localise and characterise.

Dose optimisation

  • Weight-based administered activity from the EANM paediatric dosage card or the 2024 North American consensus (e.g. ⁹⁹ᵐTc-MDP 9.3 MBq/kg, minimum 37 MBq).
  • Child-friendly environment, immobilisation and, rarely, sedation.
  • Choose the lowest-dose test that answers the question (ALARA).

Pitfalls

  • Growth-plate activity can mask or mimic disease.
  • Movement degrades images — attention to comfort/immobilisation.
  • Always justify and optimise dose.
Evidence & guidelines
  • EANM paediatric dosage card and 2024 North American consensus guidelines (Treves et al., J Nucl Med Technol 2025;53:193–197), harmonised since 2014 (Lassmann et al., Eur J Nucl Med Mol Imaging 2014;41:1036–1041).
  • ALARA and justification underpin all paediatric imaging.
In depth
  • North American consensus guidelines recommend ⁹⁹ᵐTc-MDP 9.3 MBq/kg (minimum 37 MBq, maximum 740 MBq), with delayed imaging 2–4 h after injection; the EANM paediatric dosage card is the European weight-based alternative.
  • Paediatric ¹⁸F-NaF activity is weight-based: 1.85 MBq/kg (minimum 18.5 MBq, maximum 148 MBq) in the 2024 North American update (earlier guidance 2.22 MBq/kg); axial skeleton imaging can begin 30–45 min after injection.
  • ¹⁸F-fluoride has faster blood clearance and about two-fold higher bone uptake than ⁹⁹ᵐTc-MDP, and PET provides higher spatial resolution than single-photon imaging.
  • Three-phase bone scan: flow images at 1–3 s/frame for about 60 s, blood-pool images within 10 min, and delayed images at 2–4 h; it is the test of choice for osteomyelitis when bone is not affected by other remodelling (normal radiographs), with reported sensitivity and specificity around 94–95%.
  • A pinhole collimator with a small aperture insert gives higher-resolution images of small structures such as the femoral capital epiphysis, hand and foot, and is used mainly in infants and children.
  • Non-ossified cartilage (e.g. navicular) shows no uptake and appears cold, whereas growth plates/apophyses show intense physiological uptake.
  • Bone scans usually become positive within 24–72 h of the onset of osteomyelitis; whole-body imaging is advisable because disease can be multifocal, especially in neonates (about 40% in one series).
  • SPECT is recommended for suspected spondylolysis; in one large paediatric series it showed abnormalities in about 30% of patients whose planar images were normal.
  • In suspected abuse, ¹⁸F-NaF PET had 85% sensitivity for all fractures and 92% for thoracic (93% for posterior rib) fractures, but was less sensitive than skeletal survey for classic metaphyseal lesions (67% vs 80%), so radiographs remain necessary.

Sources: North American consensus guidelines 2024 update (PMID 40664486) · SNMMI Bone Scintigraphy 4.0 · SNM ¹⁸F-NaF PET/CT guideline 1.0 · Grant et al. J Nucl Med 2008 (PMID 18077529) · Schauwecker AJR 1992 (PMID 1727365) · Wong et al. Pediatr Infect Dis J 1995 (PMID 8745016) · Jaramillo et al. Radiology 2017 (PMID 28514223) · Bellah et al. Radiology 1991 (PMID 1829845)

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