Paediatric Nuclear Medicine
Report template: Diuretic renography (Tc-99m MAG3 / DTPA) · Hepatobiliary scintigraphy (Tc-99m mebrofenin / disofenin)
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Solve questions (24) →Contents
- 23.1 Paediatric Dose Calculations (EANM Dosage Card)
- 23.2 Paediatric Renal Scintigraphy (DMSA, MAG3)
- 23.3 Paediatric MIBG (Neuroblastoma)
- 23.4 Paediatric Bone Scintigraphy
- 23.5 Paediatric GI Applications (Meckel, GER, Bleeding)
- 23.6 Paediatric Radiation Safety (ALARA, Image Gently)
- Key Points for the Board
- Current guidelines on this chapter's topics
Learning objectives and modules3 modules · about 2 h 25 min
Learning objectives
After this chapter you will be able to:
- Calculate paediatric activity with the EANM dosage card and apply the minimum activity rule.
- Explain the indications, technique and interpretation of renal scintigraphy (DMSA, MAG3) in children.
- Explain the preparation, interpretation and scoring of MIBG scintigraphy in neuroblastoma.
- Distinguish growth plates and age-specific normal findings from pathology on paediatric bone scintigraphy.
- Apply gastrointestinal studies in children and the principles of radiation safety (ALARA, sedation).
Modules
The chapter is divided into study modules without changing the order of the text: read, watch the animations, then answer the questions linked to those headings.
- Module 123.1–23.2 Paediatric Dose Calculations (EANM Dosage Card) · Paediatric Renal Scintigraphy (DMSA, MAG3)55 min · 2 animations · 22 questionsAnswer the questions →
- Module 223.3–23.4 Paediatric MIBG (Neuroblastoma) · Paediatric Bone Scintigraphy55 min · 28 questionsAnswer the questions →
- Module 323.5–23.6 Paediatric GI Applications (Meckel, GER, Bleeding) · Paediatric Radiation Safety (ALARA, Image Gently) · Key Points for the Board35 min · 10 questionsAnswer the questions →
Times are estimates: 130 words per minute, 3 min per animation, 1.5 min per question.
MOST FREQUENTLY ASKED IN THIS CHAPTER
✓
EANM Dosage Card or North American Consensus Guidelines → standard references
✓
3 kg → multiplier 1 (baseline activity), 68 kg → multiplier 14 (adult dose)
✓
Do not go below the minimum dose → inadequate image → repeat study → more radiation
✓
Giving the adult dose directly is never acceptable
✓
Webster and Clark rules are historical and not recommended in current practice
✓
DMSA: most sensitive method for acute pyelonephritis (90-95%), imaging after 2-4 hours
✓
Acute pyelonephritis → swelling; renal scar → volume loss, contour retraction → follow-up DMSA after 6 months to differentiate
23.1 Paediatric Dose Calculations (EANM Dosage Card)9 questions
Basic Principles
The most critical issue in paediatric nuclear medicine is optimisation of radiation dose. Children are more sensitive to radiation than adults because:
•
High cell division rate → more radiosensitive tissues
•
Long life expectancy → more time for stochastic effects (cancer) to appear
•
Small body size → higher absorbed dose per unit mass for the same activity
•
Small organ sizes → higher dose to the target organ
Basic Principle: giving the adult dose directly is never acceptable. The paediatric dose must be calculated according to body weight or body surface area.
EANM Dosage Card (European Association of Nuclear Medicine)
The EANM Dosage Card is the most widely used standard dose calculation system in paediatric nuclear medicine.
Calculation Method:
Paediatric Dose = Baseline Activity × Multiplier (by body weight)
•
A separate baseline activity is defined for each radiopharmaceutical
•
A table of multipliers by body weight is used
•
A minimum dose limit is set → should not be gone below, so that image quality is acceptable
EANM Weight-Based Multiplier Table (Class B; multipliers differ in classes A and C):
| Body Weight (kg) | Multiplier |
|---|---|
| 3 | 1 |
| 4 | 1.14 |
| 6 | 1.71 |
| 8 | 2.14 |
| 10 | 2.71 |
| 12 | 3.14 |
| 14 | 3.57 |
| 16 | 4.00 |
| 18 | 4.43 |
| 20 | 4.86 |
| 22 | 5.29 |
| 26 | 6.14 |
| 30 | 6.86 |
| 34 | 7.72 |
| 40 | 8.86 |
| 50 | 10.71 |
| 60 | 12.71 |
| 68 (≥68 = adult) | 14.00 |
Try it in the calculator: Paediatric activity →
BOARD TIP
▸
"What is the multiplier for a 3 kg child on the EANM dosage card?"
→ 1 (the baseline activity itself).
▸
"When is the adult dose given?"
→ ≥68 kg → multiplier 14.
▸
"Why is the minimum dose important?"
→ If too low a dose is given, image quality is inadequate → non-diagnostic image → the study may need to be repeated → more radiation.
Paediatric Minimum Activities Specified in EANM Guidelines (Examples):
| Radiopharmaceutical / Study | Minimum Activity |
|---|---|
| Tc-99m pertechnetate (thyroid) | 10 MBq |
| Tc-99m MAG3 | 15 MBq |
| Tc-99m DMSA | 18.5 MBq |
| Tc-99m DTPA (renography) | 20 MBq |
| Tc-99m pertechnetate (Meckel), labelled red cells, HIDA | 20 MBq |
| F-18 FDG (oncology / brain) | 26 MBq / 14 MBq |
| I-123 MIBG | 37 MBq |
| Tc-99m bisphosphonate (bone) | 40 MBq |
| Tc-99m HMPAO/ECD (brain perfusion) | 100 MBq |
Other Dose Calculation Methods
North American Consensus Guidelines (2010, updated 2014):
•
Widely used in the USA and Canada
•
Dose recommendations per radiopharmaceutical in MBq/kg or mCi/kg
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Minimum and maximum dose limits are set
•
Consistent with the EANM card but with small differences for some radiopharmaceuticals
Clark's Rule (Weight-Based; ≈ kg/70):
Paediatric Dose = [Weight (kg) / 70] × Adult Dose
•
Simple calculation, but the dose may be insufficient at low weights
•
In current practice the EANM card or North American Guidelines are preferred
Clark's Rule (Weight-Based, pounds):
Paediatric Dose = [Weight (lb) / 150] × Adult Dose
Body Surface Area (BSA) Method:
Paediatric Dose = [BSA (m²) / 1.73] × Adult Dose
•
Preferred in some centres
•
May give an excessively low dose in very small children → watch the minimum dose limit
BOARD TIP
▸
"If the board exam asks about paediatric dose calculation?"
→ EANM Dosage Card or North American Consensus Guidelines → these are the standard references. Webster and Clark rules are of historical importance but not recommended in current practice.
Left: a child and a 68 kg adult silhouette with the weight; in step two the class, baseline and minimum activity of the chosen radiopharmaceutical and the administered activity in a syringe. Right: classes A, B, C and Clark's rule as percent of the 68 kg activity; in step two the baseline × multiplier curve, the minimum activity line and the administered activity.
Continuous stream · no seeking
Paediatric activity = baseline activity × weight multiplier; if the result falls below the minimum activity, the minimum is given.
Source: EANM Dosage Card (Version 5.7.2016) multipliers, baseline and minimum activities; Clark's rule from the book (23.1). Height for drawing only, approximate from WHO/CDC medians.
How to use: a single click on the drawing pauses and resumes; use the time bar below to set the body weight; in the second step ↑ ↓ or the buttons below change the radiopharmaceutical; ← → change steps.
Did this animation help you understand the topic?
Figure 23.1: Comparison of the EANM dosage card (class B) with Clark's rule, and application of the minimum activity for Tc-99m DMSA.
Sedation and Patient Preparation
Sedation:
•
In young children (usually <5-6 years) sedation may be needed to prevent motion artefact
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Especially for SPECT, PET/CT and long acquisitions
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The sedation protocol should be coordinated with the anaesthesia team
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EANM 2023: imaging can be done without sedation in most children; the decision to sedate is individual, and the need has fallen with newer, faster systems. PET/MR may require sedation between 3-6 months and 6 years of age (MR sequences lengthen the study). For brain FDG PET, sedation or general anaesthesia is given after the injection and before acquisition so that it does not affect regional glucose metabolism. Sedation is performed only by an authorised team (anaesthetist) with monitoring and age-appropriate resuscitation equipment; acute complications ~0.4%. Fasting (ASA): clear liquids 2 hours, breast milk 4 hours, formula and cow's milk and a light meal 6 hours, a fatty meal ≥8 hours
•
Alternatives: feed-and-sleep technique (in infants → natural sleep after feeding), distraction techniques, swaddling
Feed-and-Sleep Technique:
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Effective especially in infants <1 year
•
Radiopharmaceutical injection → feeding → natural sleep → imaging
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Reduces the need for sedation → safety advantage
Patient Preparation – General Principles:
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Age-appropriate explanation (to the child and family)
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Intravenous access: painless cannulation with EMLA cream (topical anaesthetic) where possible
–
EANM 2023: lidocaine-prilocaine cream is applied 1 hour before venous access; whenever possible the line is placed in advance by a team experienced in paediatric venepuncture. If a cannula is already in place, it is used for injection and flushed with sufficient saline. Promising a small reward for keeping the arm still until the injection ends, and distraction, improve cooperation
•
Hydration: adequate fluid intake → speeds radiopharmaceutical clearance, reduces bladder dose
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Frequent voiding/nappy changes → reduce bladder dose
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Immobilisation: vacuum cushion, sandbags, Velcro straps
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EANM 2023: bladder catheterisation is not routinely recommended (infection risk, stress); some diuretic renal studies are the exception. The diaper is changed before positioning to avoid contamination artefacts. Immobilisation is done with the consent of the child and family (it is not restraint); the airway and breathing are checked often. The caregiver's presence in the room is encouraged; age-appropriate distraction (stories, songs, videos). An illustrated booklet or video sent a week before the appointment reduces the child's distress and the need for sedation. Radiation dose is explained to the family with familiar comparisons such as natural background or flight time. A fasting child having FDG PET is given water only
23.2 Paediatric Renal Scintigraphy (DMSA, MAG3)13 questions
Tc-99m DMSA Renal Cortical Scintigraphy
Indications:
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Diagnosis of acute pyelonephritis (most sensitive method)
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Assessment of renal scarring (permanent damage after infection)
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Calculation of differential renal function
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Assessment of congenital anomalies such as ectopic kidney, horseshoe kidney and duplex collecting system
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Assessment of a renal mass (functional renal tissue vs mass)
Mechanism:
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Tc-99m DMSA binds to proximal tubular cells → cortical fixation
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2-4 hours after injection, 40-50% of the dose is retained in the renal cortex (SNMMI/EANM 2022: 40-65% at 2 hours)
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Not excreted by glomerular filtration → tubular binding
Protocol:
•
Dose: calculated according to the EANM card (baseline activity: 6.8 MBq, minimum dose: 18.5 MBq)
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Imaging 2-4 hours after injection (waiting until cortical fixation is complete)
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Posterior projection (standard) + posterior oblique projections
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Pinhole collimator → high resolution (especially in young children)
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SPECT/CT → better assessment of cortical defects
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SNMMI/EANM 2022: imaging usually at 2-3 hours; later if renal function is poor, and up to 24 hours with marked obstruction (furosemide if needed). SPECT is suggested for every patient where possible; in infants, pinhole images (3-4 mm aperture) of each kidney separately are used instead. Pinhole and SPECT take 20-30 min, so young children may need sedation. Activity per the EANM dosage card (2016) or the North American consensus. Differential function may be overestimated in a hydronephrotic kidney and may fall in the normal range in bilateral disease. Normal variants: relatively reduced poles next to a column of Bertin, upper-pole attenuation by the liver, a linear interrenicular septum from the hilum on SPECT, fetal lobulation and junctional parenchymal defect (separated by US)
Differential Renal Function:
•
Normal: each kidney 45-55% of total function (symmetric)
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<45% → relative reduction in function
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<10% → severe loss of function (non-functioning kidney is considered)
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Calculated with the geometric mean method (anterior + posterior images)
Findings in Acute Pyelonephritis:
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Focal or multifocal areas of reduced uptake in the renal cortex
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Increased kidney size (swelling)
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Irregular cortical contour
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DMSA is the most sensitive imaging method for acute pyelonephritis (90-95% sensitivity) → superior to ultrasound
Findings in Renal Scarring:
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Focal uptake defect with cortical thinning
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Cortical contour retraction
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Volume loss
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Differentiation from acute pyelonephritis: scar → volume loss and contour retraction; acute infection → swelling
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Timing (SNMMI/EANM 2022): to confirm acute pyelonephritis, the scan is done during the infection or within 2 weeks; if defects are present it is repeated 6 months later. If only scarring is sought, the scan is done at least 6 months after the most recent urinary tract infection. Acute and permanent lesions cannot always be separated: a large polar area with indistinct margins and no contour deformity favours healing, whereas a photopenic area with contour retraction or volume loss favours a permanent scar
BOARD TIP
▸
"Most sensitive imaging method in acute pyelonephritis?"
→ Tc-99m DMSA scintigraphy (90-95% sensitivity).
▸
"When is DMSA imaged?"
→ 2-4 hours after injection (time for cortical fixation).
▸
"Acute pyelonephritis vs renal scar?"
→ Acute → swelling, increased volume; scar → volume loss, contour retraction. A follow-up DMSA after 6 months is recommended for definitive differentiation.
Figure 23.2: Normal, acute pyelonephritis and renal scar patterns on posterior Tc-99m DMSA images (schematic).
Did this figure help you understand the topic?
Tc-99m MAG3 Diuretic Renography
Indications:
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Ureteropelvic junction (UPJ) obstruction
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Ureterovesical junction (UVJ) obstruction
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Assessment of megaureter
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Assessment of hydronephrosis (obstructive vs non-obstructive dilatation)
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Postnatal assessment of prenatal hydronephrosis
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In prenatal hydronephrosis the first postnatal study is US, performed after the first 48-72 hours because of physiological oliguria; if dilatation persists, VCUG and MAG3 diuretic renography at 4-6 weeks are performed
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Calculation of differential renal function
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Assessment of renal transplant
Why MAG3?
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Tc-99m MAG3 → excreted by tubular secretion (~95-98% tubular; glomerular filtration negligible)
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High extraction fraction → good image quality even in patients with low GFR (neonates, infants)
•
Tc-99m DTPA → excreted by glomerular filtration → image quality may be inadequate in neonates because GFR is low
BOARD TIP
▸
"Why is MAG3 preferred for paediatric diuretic renography?"
→ GFR is low in neonates and infants → inadequate image quality with DTPA (glomerular filtration) → MAG3 is excreted by tubular secretion → high extraction fraction → good images even at low GFR.
Diuretic Renography Protocols:
| Protocol | Furosemide Timing | Explanation |
|---|---|---|
| F+20 | 20 min after radiopharmaceutical injection | Standard protocol → baseline renogram first, then diuretic |
| F-15 | 15 min before the radiopharmaceutical | "Well-tempered" renogram → diuretic given beforehand → collecting system emptied → obstruction clearer |
| F0 | Simultaneously with the radiopharmaceutical | Rapid protocol |
Paediatric Diuretic Renography – Special Considerations:
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Furosemide dose: 1 mg/kg IV (maximum 40 mg)
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Hydration: adequate hydration before the study is critical → false-positive obstruction in a dehydrated child
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Bladder catheter: especially in young children → a full bladder may cause pseudo-obstruction by back-pressure → the bladder is emptied with a catheter
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Neonate: renal maturation incomplete within 1 month of birth → low GFR → a pseudo-obstructive pattern may occur → assessment after 4-6 weeks is recommended (except in emergencies)
•
In a term neonate GFR is ~20-30% of the adult value, rises rapidly in the first weeks and reaches adult level at ~1-2 years; therefore faint kidneys, high background and prolonged transit may be normal in the neonate
Renogram Curve Interpretation:
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Type I (Normal): rapid uptake → peak → rapid fall (normal drainage)
•
Type II (Obstructive): continuously rising curve → no fall after furosemide → obstruction
•
Type IIIa (Dilated non-obstructive): slowly rising curve → rapid fall after furosemide → dilatation but no obstruction
T½ (Half-Emptying Time):
•
The time for activity in the collecting system to fall by half after furosemide
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<10 minutes: normal drainage (no obstruction)
•
10-20 minutes: indeterminate (equivocal) → clinical correlation needed
•
>20 minutes: suggests obstruction
BOARD TIP
▸
"T½ <10 min on diuretic renography?"
→ Normal (no obstruction).
▸
"T½ >20 min?"
→ Suggests obstruction.
▸
"Causes of a pseudo-obstructive pattern in the neonate?"
→ Immature kidney (low GFR), dehydration, full bladder.
▸
"Why is a bladder catheter inserted?"
→ Back-pressure from a full bladder → pseudo-obstruction.
Tc-99m MAG3 moves through the kidney from the vessels to the parenchyma, calyces, pelvis and ureter; the renogram curve, Tmax and T½ and the post-diuretic curve types (I, II, IIIa, IIIb, IV) are shown.
Continuous stream · no seeking
Key point: the renogram's shape reflects the transit of the tracer through the kidney; after furosemide a T½ under 10 minutes excludes obstruction, over 20 minutes suggests obstruction.
Source: book (normal Tmax 3–5 min, T½ < 10 min; post-diuretic < 10 / 10–20 / > 20 min); curves from a schematic compartment model, kidney anatomy schematic (seven pyramids, minor and major calyces: OpenStax Anatomy & Physiology 2e §25.3).
Did this animation help you understand the topic?
Figure 23.3: MAG3 diuretic renogram curve types (F+20) and interpretation of T½ after furosemide (schematic).
Assessment of Vesicoureteral Reflux (VUR)
Direct Radionuclide Cystography (DRC):
•
Tc-99m pertechnetate or Tc-99m sulphur colloid is instilled into the bladder through a catheter
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Dynamic imaging during bladder filling and during voiding
•
Presence of VUR → reflux of radioactivity into the ureters and/or renal pelvis
•
Advantages: much lower radiation dose than conventional VCUG (~50-100 times lower), continuous dynamic imaging
Indirect Radionuclide Cystography:
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After Tc-99m MAG3 diuretic renography → imaging when the bladder is full and during voiding
•
No catheter needed → non-invasive
•
Can be used in toilet-trained children (usually >2-3 years)
•
Sensitivity lower than the direct method
•
Report content (SNMMI/EANM paediatric diuresis renography 2018): in addition to the common items (see 27), previous surgery and other imaging results, volume and route of hydration given in the department, urine output during the study, any nephrostomy and how long it was clamped, furosemide dose and timing. Findings: size, shape and position of the kidneys, cortical defects, sites of retention in parenchyma, calyces, pelvis and ureters before and after furosemide; differential renal function and drainage parameters (T½, percentage drainage at the end of dynamic imaging; gravity-assisted drainage and NORA if done), shape of the post-furosemide curve (flat, rising, biphasic) and whether flank pain occurred during the study
–
Report content (SNMMI/EANM paediatric DMSA 2022): in addition to the common items (see 27), time since the last febrile urinary tract infection (at least 6 months for interpreting a permanent scar), imaging time and projections, use of pinhole or SPECT, sedation if needed. Findings: size, shape and position of the kidneys, number and site of cortical defects, differential function and method (geometric mean in hydronephrosis or ectopic kidney); limitations such as motion, activity retained in the collecting system or tubular disease. The conclusion should answer the clinical question even when no abnormality is found
VCUG vs DRC Comparison:
| Feature | VCUG (Voiding Cystourethrography) | DRC (Direct Radionuclide Cystography) |
|---|---|---|
| Radiation dose | High | Very low (~50-100 times lower) |
| Anatomical detail | Excellent | Limited |
| VUR grading | YES (Grade I-V) | Coarse (3 levels) |
| Urethral assessment | YES | NO |
| Continuous monitoring | NO (intermittent fluoroscopy) | YES (continuous dynamic) |
| Detection of intermittent reflux | Low | High |
| Initial assessment | Preferred (anatomical information) | Not preferred |
| Follow-up | Less preferred (high dose) | Preferred (low dose) |
BOARD TIP
▸
"Initial assessment of VUR?"
→ VCUG (anatomical detail, grading, urethral assessment).
▸
"For VUR follow-up?"
→ Direct radionuclide cystography (DRC) → very low radiation dose.
▸
"When is indirect cystography used?"
→ In toilet-trained children; no catheter needed.
23.3 Paediatric MIBG (Neuroblastoma)16 questions
Neuroblastoma – General Information
•
The most common extracranial solid tumour of childhood
•
Arises from the sympathetic nervous system (neural crest cells)
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Most common location: adrenal medulla (35-40%), followed by paraspinal ganglia
•
Age at diagnosis: median 18 months (90% of cases <5 years)
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Secretes catecholamines → raised urinary VMA (vanillylmandelic acid) and HVA (homovanillic acid)
•
Sites of metastasis: bone marrow, bone (skull and orbital involvement causes periorbital ecchymosis), lymph nodes, liver and skin; lung and brain metastases are rare. Thoracic (posterior mediastinal) neuroblastoma has a better prognosis than abdominal tumours
•
Prognosis: related to age, stage, MYCN amplification, histology and ploidy
•
MYCN amplification → marker of poor prognosis
•
Other adverse prognostic factors: age ≥18 months, 1p36 and 11q deletions, diploidy (hyperdiploidy or a DNA index >1 is favourable), unfavourable (INPC/Shimada) histology, high ferritin, LDH and NSE
•
Stage 4S (special stage): <12 months, localised tumour + metastases (liver, skin, bone marrow <10%) → spontaneous regression may occur → good prognosis
I-123 MIBG Scintigraphy
MIBG (Metaiodobenzylguanidine):
•
Norepinephrine analogue → specific uptake in sympathoadrenal tissue
•
Taken into the cell by the uptake-1 mechanism (norepinephrine transporter – NET)
•
High NET expression in neuroblastoma → MIBG uptake
I-123 vs I-131 MIBG (Diagnostic Use):
| Feature | I-123 MIBG | I-131 MIBG |
|---|---|---|
| Gamma energy | 159 keV | 364 keV |
| Half-life | 13.2 hours | 8.02 days |
| Beta emission | None | Present (therapeutic effect) |
| Image quality | Superior (low energy → ideal for the gamma camera) | Low |
| SPECT feasibility | YES (excellent) | Limited |
| Radiation dose | Low | High |
| Paediatric preference | Preferred | Not recommended for diagnosis |
BOARD TIP
▸
"Which isotope is preferred for diagnostic MIBG in neuroblastoma?"
→ I-123 → low energy (159 keV, ideal for the gamma camera), SPECT possible, low radiation dose, superior image quality. I-131 is not recommended for diagnosis in paediatric patients (high dose, low image quality).
Patient Preparation:
•
Thyroid blockade: to prevent thyroid uptake of free iodine
–
Potassium iodide (KI) or Lugol's solution
–
Started 24 hours before MIBG injection
–
I-123 MIBG: for 2-3 days
–
I-131 MIBG therapy: started 1-2 days before, continued until 2 weeks after treatment
•
Drug interactions: drugs that reduce MIBG uptake should be stopped:
–
Tricyclic antidepressants, cocaine, amphetamine → uptake-1 inhibition
–
Reserpine → inhibition of vesicular storage; labetalol → uptake-1 inhibition (+ depletion)
–
Calcium channel blockers → may reduce uptake
–
Phenylephrine, pseudoephedrine (decongestants) → competitive inhibition
Protocol:
•
Dose: according to the EANM card (I-123 MIBG baseline activity: 28 MBq, minimum dose: 37 MBq)
•
IV injection (slowly, over 1-2 minutes)
•
Imaging: 24 hours after injection (delayed images → tumour/background ratio increases)
•
Whole-body scan + regional SPECT/CT
•
Early images at 4 hours may also be acquired
Normal Biodistribution:
•
Salivary glands, heart, liver, spleen, bladder, bowel
•
Adrenal glands (faint, symmetric)
•
Nasal mucosa
•
Brown fat (especially in a cold environment → supraclavicular, paravertebral)
MIBG Findings in Neuroblastoma:
•
Intense focal uptake in the primary tumour
•
Assessment of metastases: bone, bone marrow, lymph nodes, liver, orbit
•
90-95% of neuroblastomas are MIBG-positive
•
MIBG-negative neuroblastoma (5-10%) → FDG PET/CT or F-18 DOPA PET as alternatives
•
Normal uptake and pitfalls: the parotid and submandibular glands, nasopharynx, myocardium, liver (heterogeneous, more prominent in the left lobe) and adrenals normally take up MIBG; the renal collecting system, bladder and sometimes the colon are seen through excretion. Low, symmetrical uptake in the lacrimal glands, uterine uptake during the menstrual cycle and uptake in supraclavicular, intercostal and pararenal brown fat (usually bilateral) may occur; the thyroid is seen if not fully blocked. In a patient whose adrenal was removed with the tumour, prominent uptake in the contralateral adrenal is a physiological finding due to hyperplasia (Bar-Sever 2018)
–
False positives: mature ganglioneuroma or other neuroendocrine tumours, physiological adrenal, salivary gland, nasopharyngeal and brown fat uptake, excretion in the renal pelvis and bladder. False negatives: about 10% of neuroblastomas have low norepinephrine transporter expression; extensive necrosis or scar, the blood-brain barrier and interfering drugs (labetalol, tricyclic antidepressants, sympathomimetics) also reduce uptake (INRG 2010; Bar-Sever 2018). SIOPEN (2026): the 24-hour whole-body planar image is always followed by SPECT/CT covering the entire trunk
Figure 23.4: Normal I-123 MIBG biodistribution and primary tumour with bone/bone marrow involvement in neuroblastoma (schematic).
Did this figure help you understand the topic?
•
EANM: the minimum activity for I-123 MIBG in children is 37 MBq; effective dose is ~6.3 mSv in neonates and ~5 mSv above 1 year
•
According to EANM, thyroid blockade is continued for 2-3 days for I-123 MIBG and 5-10 days for diagnostic I-131 MIBG, starting 1 day beforehand; it is continued longer for I-131 MIBG therapy
•
In neuroblastoma, MIBG findings do not always agree with urinary catecholamine metabolites and bone marrow aspiration results
•
Bone scintigraphy: a substantial proportion (~30-50%) of primary neuroblastomas take up Tc-99m MDP. Bone metastases may be missed because they can lie in metaphyses adjacent to the growth plate and be symmetric; MIBG is more sensitive
INRG (International Neuroblastoma Risk Group) Staging
•
INRGSS (INRG Staging System): imaging-based staging system based on IDRFs
•
L1: localised, no IDRF
•
L2: localised, IDRF present (surgical risk factors)
•
M: distant metastatic
•
MS: metastatic special (<18 months, metastases limited to skin/liver/bone marrow)
Curie Score (Semi-Quantitative MIBG Scoring)
•
Semi-quantitative assessment of MIBG uptake
•
The body is divided into 9 skeletal segments + soft tissue
•
Uptake in each segment is scored from 0-3:
–
0: no uptake
–
1: uptake in one site
–
2: uptake in more than one site
–
3: diffuse uptake in >50% of the segment
•
Maximum score: 30 (9 segments × 3 + soft tissue × 3)
•
Used to monitor treatment response
•
Curie score ≤2 → marker of good prognosis (after induction CT)
BOARD TIP
▸
"What is the Curie score?"
→ Semi-quantitative scoring of MIBG uptake → 9 skeletal segments + soft tissue → each 0-3 points → maximum 30 points.
▸
"What does a Curie score ≤2 mean?"
→ Marker of good prognosis after induction CT.
I-131 MIBG Therapy
•
For therapy in high-risk or relapsed/refractory neuroblastoma
•
I-131 MIBG → kills tumour cells by beta emission
•
Therapeutic dose: usually 444-666 MBq/kg (12-18 mCi/kg)
•
Side effects: myelosuppression (dose-limiting), hypothyroidism, salivary gland damage
•
Requires radiation isolation
•
For details → see Chapter 26.3
–
For report content see 13.3.4 (SIOPEN or Curie score, primary tumour and skeletal involvement reported separately)
23.4 Paediatric Bone Scintigraphy12 questions
Indications
•
Childhood malignancies: screening for bone metastases (neuroblastoma, Ewing sarcoma, osteosarcoma, rhabdomyosarcoma)
•
Lytic lesions in Langerhans cell histiocytosis may appear normal or cold on bone scintigraphy; the primary method is therefore a radiographic skeletal survey. FDG PET/CT is more sensitive for showing active lesions and treatment response
•
Osteomyelitis: especially when clinical/radiological findings are equivocal
•
Stress fracture and trauma: fractures not seen on radiography
•
Child abuse (non-accidental injury): screening for multiple fractures
•
Avascular necrosis: Legg-Calvé-Perthes disease
•
Skeletal dysplasias and metabolic bone diseases
Special Considerations in Paediatric Bone Scintigraphy
Normal Paediatric Findings:
•
Growth plates (physes): intense symmetric uptake → active bone growth
–
If growth plate uptake is asymmetric → pathology should be considered (infection, trauma, tumour)
•
Fontanelles: reduced uptake at open fontanelles
•
Metaphyses: active remodelling → intense uptake
•
In general: bone metabolism is high in children → more intense overall uptake than in adults
Growth Plate Asymmetry:
•
Unilateral increased uptake → infection (osteomyelitis), trauma (Salter-Harris fracture), tumour
•
Unilateral reduced uptake → vascular damage, after radiotherapy, after surgery
•
Bilateral symmetric intense uptake → normal growth plate activity
BOARD TIP
▸
"Is growth plate uptake normal on paediatric bone scintigraphy?"
→ Yes, bilateral symmetric intense uptake is normal.
▸
"What does asymmetry mean?"
→ Think of pathology → infection, trauma, tumour.
▸
"After the growth plate closes?"
→ Uptake disappears (skeletal maturation complete).
Child Abuse (Non-Accidental Injury – NAI):
•
Multiple fractures at different stages of healing → suggest abuse
•
Bone scintigraphy: whole-body scan → can detect clinically unsuspected fractures
•
Complementary to the skeletal survey (radiography) → both methods should be used together
•
Advantage of bone scintigraphy: more sensitive for rib fractures, spinous process fractures and pelvic fractures
•
Disadvantage of bone scintigraphy: low sensitivity for skull fractures (suture artefact) and for metaphyseal corner fractures (classic abuse lesion)
•
Classic metaphyseal lesion (CML / bucket-handle fracture): highly specific for abuse → seen better on radiography, may be missed on bone scintigraphy
•
Toddler's fracture (1-3 years, newly walking child): a spiral or oblique fracture of the mid-distal tibial shaft; radiography is often negative, and bone scintigraphy shows faint diffuse or oblique linear increased uptake along the tibia
•
Recommended approach: skeletal survey (radiography) as the primary method + bone scintigraphy as complementary
Legg-Calvé-Perthes Disease:
•
Avascular necrosis of the femoral head (idiopathic)
•
Common in boys aged 4-8 years
•
Bone scintigraphic findings:
–
Early stage: reduced/absent uptake in the femoral head (avascular phase → "cold" lesion)
–
In the early stage, a lens-shaped photopenic area in the superolateral femoral head; in the intermediate stage increasing uptake at the margin of the defect (lateral column) is seen, indicating revascularisation
–
Prognosis (Conway): early activity in the lateral column (recanalisation) indicates a good prognosis; neovascularisation spreading from the base of the femoral head and late filling of the lateral column indicate a poor prognosis
–
Late stage (revascularisation): increased uptake (repair phase)
•
High-resolution imaging with a pinhole collimator is recommended
Figure 23.5: Paediatric bone scintigraphy: normal symmetric physeal uptake, asymmetric physeal/metaphyseal uptake and early-stage Legg-Calvé-Perthes (schematic).
Did this figure help you understand the topic?
•
EANM: transient synovitis of the hip and osteoid osteoma are also among the indications for paediatric bone scintigraphy and SPECT/CT; the minimum activity in children is 40 MBq (~2.5 mSv)
•
EANM/SNMMI 2025: activity per the 2014 EANM dosage card (minimum 40 MBq) or the 2024 North American consensus; the same activity applies to HMDP/DPD. SPECT or SPECT/CT is performed when planar images show a localised finding and in every child with spinal or pelvic symptoms; CT is limited to the segment of interest. Current role: SPECT/CT in osteoid osteoma (CT is the most accurate modality), SPECT/CT in spondylolysis, bone scintigraphy in suspected abuse when the skeletal survey is normal but suspicion is high; in acute osteomyelitis mostly US/MRI, in subacute-chronic osteomyelitis and CRMO whole-body MRI, and in bone sarcomas FDG PET/CT or PET/MRI have taken precedence; in neuroblastoma the standard is I-123 MIBG. In children, NaF PET dosimetry at recommended activities is similar to that of MDP
•
Hip effusion (septic arthritis, transient synovitis): raised pressure within the joint capsule may compromise perfusion of the femoral head (tamponade); uptake in the femoral head falls in all phases and urgent aspiration or decompression is needed
•
MRI → the preferred method in current practice (bone marrow oedema, cartilage assessment)
•
Bone scintigraphy → used where MRI is unavailable or as a complement
Osteomyelitis:
•
In children it most commonly arises by haematogenous spread
•
Most common location: metaphysis of long bones (rich vascular supply)
•
Three-phase bone scintigraphy:
–
Phase 1 (blood flow): increased perfusion
–
Phase 2 (blood pool): increased hyperaemia
–
Phase 3 (delayed static): focal increased uptake
•
Positive in all three phases → consistent with osteomyelitis
•
Neonatal osteomyelitis: may be a photopenic ("cold") lesion → blood flow cut off by vascular thrombosis/compression → risk of false negative
•
In neonates (<6 weeks) osteomyelitis is often multifocal and destructive and occurs together with septic arthritis. At presentation radiography is often abnormal, whereas the sensitivity of bone scintigraphy is low; MRI or US is preferred. Photopenic osteomyelitis runs a more aggressive course
•
Sensitivity: 84-100%, specificity: 70-96%
BOARD TIP
▸
"Can bone scintigraphy be normal in neonatal osteomyelitis?"
→ Yes! In neonatal osteomyelitis a photopenic (cold) lesion due to vascular compromise may be seen → false-negative result.
▸
"Where is osteomyelitis most common in children?"
→ Metaphysis of long bones (haematogenous spread, rich vascular supply).
Ewing Sarcoma and Osteosarcoma:
•
Bone scintigraphy → intense uptake in the primary tumour + screening for skip metastases and distant bone metastases
•
The most common primary malignant bone tumour is multiple myeloma; the most common primary bone sarcoma is osteosarcoma (with a second peak in the elderly on a background of Paget disease or radiation); in children Ewing sarcoma comes second
•
Ewing sarcoma: diaphyseal location, "onion-skin" periosteal reaction (radiographic)
•
Ewing sarcoma most often arises in the pelvis and femur; FDG PET/CT is more sensitive than bone scintigraphy for detecting bone metastases and bone marrow involvement
•
Bone and bone marrow metastases are more common in Ewing sarcoma than in osteosarcoma; staging includes bone marrow biopsy, chest CT and bone scintigraphy or FDG PET/CT
•
Osteosarcoma: metaphyseal location, "sunburst" periosteal reaction
•
Osteosarcoma most often metastasises to the lung (chest CT is the most sensitive method); osteoid-producing lung metastases may take up MDP. Scintigraphy overestimates the primary tumour because of hyperaemia; MRI is used for margins and skip lesions
•
Bone scintigraphy → effective for detecting multiple bone metastases with a whole-body scan
•
Clear cell sarcoma of the kidney often metastasises to bone, so bone scintigraphy is needed for staging; bone metastasis is rare in Wilms tumour
•
PET/CT → increasingly used in current practice for staging and response assessment
•
Rhabdomyosarcoma most often arises in the head and neck (orbit, parameningeal), followed by the genitourinary tract; FDG PET/CT is more sensitive than conventional imaging for nodal and distant metastases, and MIBG has no role
23.5 Paediatric GI Applications (Meckel, GER, Bleeding)4 questions
Meckel Diverticulum Scintigraphy
Meckel Diverticulum:
•
Remnant of the vitellointestinal duct (omphalomesenteric duct)
•
The most common congenital GI anomaly
•
"Rule of twos": in 2% of the population, 2 feet (60 cm) proximal to the ileocaecal valve, 2 inches (5 cm) long, symptomatic under 2 years, 2 types of ectopic mucosa (gastric and pancreatic)
•
Symptoms: painless rectal bleeding (most common), intestinal obstruction, diverticulitis
•
Cause of bleeding: ectopic gastric mucosa → acid secretion → ulceration of the adjacent ileal mucosa
Tc-99m Pertechnetate Scintigraphy (Meckel Scan):
•
Tc-99m pertechnetate → taken up by gastric mucosal cells (stomach + ectopic gastric mucosa)
•
Ectopic gastric mucosa in the Meckel diverticulum → pertechnetate uptake → detected
•
Detects only Meckel diverticula containing gastric mucosa → false negative if there is no gastric mucosa
Protocol:
•
Dose: according to the EANM card
•
Patient preparation: 4-6 hours fasting
•
Anterior dynamic imaging in the supine position → 30-60 minutes
•
Focal activity filling simultaneously with the stomach → Meckel diverticulum
Typical Finding:
•
Focal increased activity in the right lower quadrant (or pelvic region) appearing simultaneously with the stomach
•
Activity intensity increases over time (gastric mucosa concentrates pertechnetate)
•
Timing parallel to gastric uptake → critical diagnostic clue
Pharmacological Interventions that Increase Sensitivity:
| Drug | Mechanism | Effect |
|---|---|---|
| Pentagastrin | Stimulates gastric mucosal cells | Increases pertechnetate uptake |
| Cimetidine (H2 blocker) | Inhibits secretion of pertechnetate from the gastric mucosa into the lumen | Increases retention in the mucosa → most commonly used |
| Glucagon | Reduces peristalsis | Reduces motion artefact, prevents luminal washout |
BOARD TIP
▸
"Most commonly used drug to increase sensitivity of Meckel scintigraphy?"
→ Cimetidine (H2 blocker) → inhibits secretion of pertechnetate from the gastric mucosa into the lumen → retention in the mucosa increases → sensitivity increases.
▸
"What does Meckel scintigraphy detect?"
→ Ectopic gastric mucosa (pertechnetate is taken up by gastric mucosal cells).
▸
"Meckel diverticulum without gastric mucosa?"
→ False negative.
Figure 23.6: Meckel diverticulum scintigraphy: focal uptake in ectopic gastric mucosa increasing simultaneously with the stomach (schematic).
Did this figure help you understand the topic?
Causes of False Positives:
•
Ureteropelvic junction obstruction (renal pelvic activity)
•
Intestinal duplication cyst (may contain gastric mucosa)
•
Inflammatory bowel disease
•
Arteriovenous malformation
•
Ureteric activity
•
Appendicitis
Causes of False Negatives:
•
Meckel diverticulum without gastric mucosa
•
Active bleeding → pertechnetate washed into the lumen
•
Small diverticulum
•
Insufficient amount of ectopic gastric mucosa
Sensitivity and Specificity:
•
In children: sensitivity 85-95%, specificity 95%
•
Sensitivity is lower in adults (60-70%) → ectopic gastric mucosa is less frequent
Gastro-oesophageal Reflux (GER) Scintigraphy
Indications:
•
Recurrent pneumonia or chronic cough (suspected aspiration)
•
Apnoeic episodes (especially in infants)
•
Failure to thrive
•
Situations where pH monitoring is insufficient
•
Assessment of aspiration (delayed images)
Protocol:
•
Tc-99m sulphur colloid → mixed with milk or formula
•
Given orally (by bottle or nasogastric tube)
•
Anterior dynamic imaging in the supine position → 60 minutes (1 s/frame)
•
Delayed images (2-24 hours): activity in the lung fields → evidence of pulmonary aspiration
Assessment:
•
Retrograde activity in the oesophagus → GER
•
Frequency, duration and proximal extent of reflux are assessed
•
Activity in the lung fields → aspiration (most important finding)
•
Gastric emptying is assessed at the same time
Advantages (compared with pH monitoring):
•
Assessment under physiological conditions (with real feeding)
•
Also detects non-acid reflux (the pH probe detects only acid reflux)
•
Can show aspiration (delayed images)
•
Assesses gastric emptying at the same time
•
Low radiation dose
Disadvantages:
•
Lower sensitivity than pH monitoring (46-80%)
•
Short imaging time → intermittent reflux may be missed
•
Lack of standardisation
Gastric Emptying Scintigraphy in Children
•
Delayed gastric emptying in children is almost always gastroparesis (no mechanical obstruction); accelerated emptying can present as dumping syndrome
•
Preparation: At least 4 hours' fasting (may be reduced to 3 hours in infants after discussion with the referrer). When the aim is to assess emptying off therapy, drugs that affect gastric emptying are stopped at least 3 days beforehand. In diabetes, blood glucose is checked before the study and reported; the target fasting value is <200 mg/dL, and at >275 mg/dL the study is postponed or the glucose lowered
•
Activity (Tc-99m sulphur colloid): 9.25-18.5 MBq (0.25-0.5 mCi) for a solid meal, 18.5-37 MBq (0.5-1 mCi) for a liquid meal
•
Liquid meal ("milk scan"): The child's own formula, milk or breast milk is used. The labelled part is given in the first bottle with one third of the volume; an unlabelled second bottle washes residual activity from the mouth and teat. The tip of a feeding tube should lie in the fundus (a meal delivered to the antrum falsely accelerates emptying). After feeding, posterior dynamic images are acquired for 60 minutes, with static images at 1 and 3 hours. If reflux is to be assessed the tube is removed before imaging; delayed chest images look for aspiration
•
Solid meal: The adult standard meal (egg white, two slices of toast, water) is used and finished within 10 minutes; at least half of the meal must be eaten for a confident interpretation. Labelled melted cheese is an alternative for children who cannot eat egg. The geometric mean of anterior and posterior images is used, with imaging immediately after the meal and hourly up to 4 hours, with decay correction
•
The emptying curve is close to linear for a solid meal and exponential for a liquid meal
BOARD TIP
▸
"Most important finding on GER scintigraphy?"
→ Activity in the lung fields on delayed images → evidence of pulmonary aspiration.
▸
"Advantage over pH monitoring?"
→ Also detects non-acid reflux + can show aspiration.
▸
"Disadvantage?"
→ Lower sensitivity.
GI Bleeding Scintigraphy
Nuclear Medicine in Paediatric GI Bleeding:
•
Tc-99m labelled red cell (RBC) study → localisation of the active bleeding site
•
Causes of GI bleeding in children: Meckel diverticulum, polyp, vascular malformation, inflammatory bowel disease, duplication cyst
Tc-99m Labelled Red Cells:
•
In vivo method: cold tin (stannous pyrophosphate) IV → Tc-99m pertechnetate IV after 20 min → binds to red cells
•
In vitro method: blood is drawn → labelled in the laboratory → reinjected (highest labelling efficiency >97%)
•
Modified in vivo (Brookhaven) method: cold tin IV → blood drawn → Tc-99m added in vitro → reinjected
Bleeding Detection Threshold:
•
Tc-99m labelled red cells: can detect bleeding at 0.1-0.4 mL/min
•
More sensitive than angiography (angiography: 0.5-1.0 mL/min)
•
Continuous or intermittent imaging → up to 24 hours → chance of catching intermittent bleeding
Paediatric Special Considerations:
•
The in vivo method is more practical in children (less blood handling)
•
Meckel diverticulum → Meckel scintigraphy (pertechnetate) first; if negative or if there is active bleeding → labelled red cell study
•
Bleeding localisation → planning of surgical or angiographic intervention
•
For details → see Chapter 18.6
23.6 Paediatric Radiation Safety (ALARA, Image Gently)6 questions
ALARA Principle
ALARA = As Low As Reasonably Achievable
•
The principle of keeping radiation dose as low as reasonably achievable
•
Especially critical in paediatric nuclear medicine → children are more radiosensitive
•
The three basic principles of radiation protection (ICRP; ALARA = optimisation):
1. Justification: it must be ensured that the study is clinically necessary 2. Optimisation: minimising dose while preserving diagnostic quality 3. Dose limitation: the set dose limits must not be exceeded
Paediatric Dose Optimisation Strategies
Radiopharmaceutical Dose:
•
The EANM Dosage Card or North American Consensus Guidelines should be used
•
Do not go below the minimum dose (inadequate image → repeat study → more dose)
•
Giving the adult dose directly is never acceptable
Acquisition Parameters:
•
Lengthening acquisition time → adequate counts obtained at a lower dose
•
Child cooperation is limited → lengthening the time must be balanced against the risk of motion artefact
•
Appropriate collimator choice (LEHR for low-energy radionuclides)
CT Dose (SPECT/CT and PET/CT):
•
Paediatric CT protocols should be used (never an adult protocol)
•
Low-dose CT → sufficient for attenuation correction and anatomical localisation
•
Automatic tube current modulation
•
Optimisation of kV and mAs settings to the child's size
•
Unnecessary diagnostic CT should be avoided (if low-dose CT is sufficient)
Image Gently Campaign
Image Gently:
•
Launched by the Alliance for Radiation Safety in Pediatric Imaging (2008)
•
Awareness campaign aimed at reducing radiation dose in paediatric imaging
•
Target audience: radiologists, nuclear medicine physicians, technologists, clinicians, families
Key Messages:
1. "Child size the radiation dose" → adjust the dose to the child's size 2. Avoid unnecessary studies → consider alternative methods (US, MRI) 3. Avoid repeat studies → get it right the first time 4. Image only the necessary region
Image Gently – Nuclear Medicine-Specific Recommendations:
•
The EANM Dosage Card or North American Consensus Guidelines should be used
•
Paediatric protocols should be applied for the CT component
•
Alternative methods should be tried instead of sedation (feed-and-sleep, distraction)
•
The appropriateness of the study indication should be questioned
•
Go With the Guidelines Campaign: joint nuclear medicine campaign of Image Gently and SNMMI (2012)
•
Guideline-based paediatric dose adjustment (Step Lightly: interventional radiology)
•
Recommendations:
–
Appropriate choice of radiopharmaceutical and dose
–
Minimisation of CT dose in hybrid imaging (SPECT/CT, PET/CT)
–
Avoiding unnecessary studies
–
Patient and family education
Paediatric Radiation Risk
Reasons for Increased Radiation Risk in Children:
•
High cell division rate → more radiosensitive tissues
•
Long life expectancy → more time for stochastic effects to appear
•
Small body size → higher absorbed dose per unit mass
•
Some organs (thyroid, gonads, bone marrow) are more radiosensitive in children
Organ-Specific Risks:
•
Thyroid: the risk of thyroid cancer is markedly higher in children than in adults (especially <5 years)
•
Bone marrow: the proportion of active marrow is higher in children → leukaemia risk
•
Gonads: potential effect on fertility
•
Breast tissue: radiation exposure before and during puberty → increased breast cancer risk
Effective Dose Comparison (Approximate Values):
| Study | Adult Effective Dose (mSv) | Paediatric Effective Dose (mSv) – 5 years |
|---|---|---|
| Tc-99m DMSA | 0.9 | 1.6 |
| Tc-99m MAG3 | 0.7 | 1.2 |
| Tc-99m MDP (bone) | 4.2 | 6.3 |
| Tc-99m pertechnetate (Meckel) | 1.5 | 2.8 |
| I-123 MIBG | 2.5 | 4.0 |
Parent and Patient Education
•
Families should be given understandable information about radiation dose
•
Comparison with natural background radiation can be made
•
The benefit vs risk balance of the study should be explained
•
In breastfeeding mothers: the breastfeeding interruption period for the radiopharmaceutical should be stated
–
Tc-99m agents: most need no interruption/≤4 hours (pertechnetate, MAA, RBC: 12 hours)
–
I-123: NaI 3-4 days, MIBG ≥24 hours interruption
–
I-131: breastfeeding must be stopped completely
–
For details → see Chapter 10.7
BOARD TIP
▸
"What is Image Gently?"
→ Awareness campaign aimed at reducing radiation dose in paediatric imaging (Alliance for Radiation Safety in Pediatric Imaging, 2008).
▸
"What is Go With the Guidelines?"
→ Image Gently + SNMMI nuclear medicine campaign (Step Lightly: interventional radiology).
▸
"Why is radiation risk higher in children?"
→ High cell division rate + long life expectancy + small body size.
▸
"Golden rule for paediatric dosing?"
→ Use the EANM Dosage Card or North American Consensus Guidelines; never give the adult dose directly.
Key Points for the Board
Paediatric Dose Calculation:
•
EANM Dosage Card or North American Consensus Guidelines → standard references
•
3 kg → multiplier 1 (baseline activity), 68 kg → multiplier 14 (adult dose)
•
Do not go below the minimum dose → inadequate image → repeat study → more radiation
•
Giving the adult dose directly is never acceptable
•
Webster and Clark rules are historical and not recommended in current practice
Paediatric Renal Scintigraphy:
•
DMSA: most sensitive method for acute pyelonephritis (90-95%), imaging after 2-4 hours
•
Acute pyelonephritis → swelling; renal scar → volume loss, contour retraction → follow-up DMSA after 6 months to differentiate
•
MAG3: preferred for paediatric diuretic renography → tubular secretion → good images even at low GFR
•
DTPA is inadequate in neonates (low GFR)
•
Diuretic renography T½: <10 min normal, 10-20 min indeterminate, >20 min obstruction
•
Bladder catheter → prevents the back-pressure effect (pseudo-obstruction)
•
In neonates wait 4-6 weeks (renal maturation)
Assessment of VUR:
•
Initial assessment → VCUG (anatomical detail, grading, urethral assessment)
•
Follow-up → DRC (50-100 times lower radiation dose)
•
Indirect cystography → no catheter needed, in toilet-trained children
Neuroblastoma and MIBG:
•
Drugs that reduce MIBG uptake: tricyclic antidepressants, cocaine, amphetamine (uptake-1 inhibition); reserpine (inhibition of vesicular storage); labetalol (uptake-1 inhibition); phenylephrine, pseudoephedrine (competitive inhibition)
•
The most common extracranial solid tumour of childhood
•
Neural crest origin, most often the adrenal medulla
•
Diagnostic MIBG → I-123 preferred (low energy, SPECT possible, low dose)
•
90-95% of neuroblastomas are MIBG-positive
•
MIBG-negative → FDG PET/CT or F-18 DOPA PET
•
Thyroid blockade is mandatory (KI or Lugol, start 24 hours before)
•
Stage 4S (MS): <12 months (<18 months in INRGSS), localised + limited metastases → spontaneous regression may occur
•
Curie score: 9 skeletal segments + soft tissue → each 0-3 → max. 30 → response monitoring → ≤2 good prognosis
•
MYCN amplification → poor prognosis
Paediatric Bone Scintigraphy:
•
Growth plates → bilateral symmetric intense uptake = normal
•
Asymmetry → pathology (infection, trauma, tumour)
•
Child abuse (NAI): skeletal survey (radiography) primary + bone scintigraphy complementary
•
Disadvantage of bone scintigraphy: low sensitivity for skull fracture and classic metaphyseal lesion (CML)
•
Legg-Calvé-Perthes: early stage → cold lesion in the femoral head (avascular phase)
•
Neonatal osteomyelitis: may be a photopenic (cold) lesion → beware false negative!
•
Ewing sarcoma → diaphysis, osteosarcoma → metaphysis
•
Toddler's fracture (1-3 years): radiography often negative; on bone scintigraphy faint diffuse or oblique linear uptake along the tibia
•
Langerhans cell histiocytosis: lesions may be normal/cold on bone scintigraphy → radiographic skeletal survey is the mainstay; FDG PET/CT more sensitive
•
Perthes prognosis (Conway): early activity in the lateral column is good; neovascularisation from the base of the femoral head indicates poor prognosis
•
Tamponade in hip effusion (septic arthritis/transient synovitis) → reduced uptake in the femoral head in all phases → urgent decompression
•
Ewing sarcoma: FDG PET/CT more sensitive than bone scintigraphy for bone/bone marrow metastases
Paediatric GI:
•
Meckel scintigraphy: Tc-99m pertechnetate → uptake in ectopic gastric mucosa
–
Cimetidine → most commonly used sensitivity enhancer (inhibits secretion into the lumen)
–
Sensitivity in children 85-95%
–
Focal uptake simultaneous with the stomach → diagnostic
–
No gastric mucosa → false negative
•
GER scintigraphy: lung activity on delayed images → pulmonary aspiration (most important finding)
–
Also detects non-acid reflux (advantage over the pH probe)
Radiation Safety:
•
Image Gently (2008) → campaign to reduce radiation dose in paediatric imaging
•
Go With the Guidelines → Image Gently + SNMMI nuclear medicine campaign
•
Increased risk in children: high cell division rate + long life expectancy + small body size
•
Feed-and-sleep technique → alternative to sedation in infants <1 year
•
Breastfeeding interruption: Tc-99m → most ≤4 hours (pertechnetate/MAA 12 h), I-123 NaI → 3-4 days, I-131 → stop completely
Additional Notes from EANM Guidelines:
•
EANM dosage card: paediatric dose = baseline activity × multiplier; 3 kg → 1, 30 kg → 6.86, ≥68 kg → 14
•
Paediatric minimum activities: pertechnetate (thyroid) 10, MAG3 15, DMSA 18.5, DTPA/HIDA/Meckel/RBC 20, FDG 26, I-123 MIBG 37, bone 40, brain perfusion 100 MBq
•
I-123 MIBG thyroid blockade 2-3 days; diagnostic I-131 MIBG 5-10 days
Current guidelines on this chapter's topics
The latest guidelines and consensus documents on the procedures covered in this chapter (official EANM index and primary sources, November 2026). Comparison of the text with these versions is in progress; consult the guideline itself for details.
- 2025Joint EANM/SNMMI procedural guideline for paediatric bone hybrid imaging with 99mTc-labelled radiopharmaceuticals and [ 18F]fluoride (opens in a new tab)
- 2025The SNMMI Procedure Standard/EANM Practice Guideline for Pediatric Gastric Emptying (opens in a new tab)
- 2023EANM procedural recommendations for managing the paediatric patient in diagnostic nuclear medicine (opens in a new tab)
- 2022SNMMI procedure standard/EANM practice guideline on pediatric [99mTc]Tc-DMSA renal cortical scintigraphy: an update (opens in a new tab)
- 2022Joint EANM/SIOPE/RAPNO practice guidelines/SNMMI procedure standards for imaging of paediatric gliomas using PET with radiolabelled amino acids and [18F]FDG: version 1.0. (opens in a new tab)
- 2021SNMMI Procedure Standard/EANM Practice Guideline on Pediatric 18F-FDG PET/CT for Oncology 1.0 (opens in a new tab)
- 2018The SNMMI and EANM Procedural Guidelines for Diuresis Renography in Infants and Children (opens in a new tab)
- 2018Guidelines on nuclear medicine imaging in neuroblastoma (opens in a new tab)
- 2014Paediatric Radiopharmaceutical Administration: Harmonization of the 2007 EANM Pediatric Dosage Card (version 1.5.2008) and the 2010 North America Consensus guidelines (opens in a new tab)
- 2007Guidelines for Lung Scintigraphy in Children (opens in a new tab)
- 2003Guidelines for Direct Radionuclide Cystography in Children (opens in a new tab)
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