Is ultrasound effective for identifying neuroblastoma in a child?

Ultrasound for Neuroblastoma Detection in Children

Ultrasound is effective as an initial imaging modality for detecting neuroblastoma in children, particularly for identifying abdominal masses, but has significant limitations in fully characterizing tumor extent and should be followed by cross-sectional imaging (CT or MRI) for complete evaluation. 1, 2

Role of Ultrasound in Initial Detection

Primary Screening and Detection

• Ultrasound serves as the preferred first-line imaging modality for suspected neuroblastoma in young children, especially infants, due to its non-invasive nature, lack of radiation exposure, and ability to identify abdominal masses. 1
• Approximately 50% of neuroblastoma patients present with localized or regional disease, and ultrasound can effectively identify the primary abdominal mass in these cases. 1
• Ultrasound is specifically recommended for surveillance in high-risk populations, such as children with SMARCB1 mutations (ages 0-5 years), where it is used every 4-6 weeks in infants 0-6 months and every 2-3 months from 6 months to 5 years. 1
• For children with Costello syndrome and HRAS mutations, abdominopelvic ultrasound should begin as soon as the genetic variant is identified and continue until age 10 years for neuroblastoma screening. 1

Limitations of Ultrasound Alone

• Ultrasound has significant limitations in evaluating the full extent of neuroblastoma, including assessment of vascular encasement, lymphadenopathy, and invasive growth patterns. 2
• Sonography cannot reliably delineate tumor extent or accurately follow response to therapy, and total resolution of abdominal disease cannot always be diagnosed with ultrasound alone. 3
• Heavily calcified residual neuroblastoma may be mistaken for bowel gas on ultrasound, leading to false-negative interpretations. 3
• Sensitivity may decrease in older children due to body habitus limitations, requiring transition to MRI when ultrasound is considered non-diagnostic. 1

Recommended Imaging Algorithm

Initial Evaluation

• Cross-sectional imaging with MRI (with/without contrast) or CT (with contrast) is required for definitive evaluation of soft tissue disease at initial diagnosis, not ultrasound alone. 1
• The combination of imaging studies depends on symptoms and suspected disease sites, with the primary goals being identification of neuroblastoma features, assessment of image-defined risk factors (IDRFs), and evaluation of metastatic disease. 1

Comparative Imaging Performance

• CT and MRI are superior to ultrasound for evaluating local disease, with no significant difference between CT and MRI in assessing tumor location or size. 2
• MRI more distinctly demonstrates intraspinal extension compared to both CT and ultrasound. 2
• Contrast enhancement at CT and MRI improves demarcation between tumor and kidney and is necessary for evaluating vessel encasement. 2

Metastatic Disease Assessment

• 123I-MIBG imaging is the gold standard for assessing metastatic disease, with high specificity and sensitivity (up to 90% uptake in neuroblastoma tumors). 1, 4
• MIBG scan has a sensitivity of 83.3% and specificity of 98.0% for neuroblastoma diagnosis, particularly valuable in opsoclonus-myoclonus-ataxia syndrome. 4
• If MIBG-nonavid disease is present, 18F-FDG-PET imaging should be obtained (except in infants <6 months with small L1 adrenal tumors). 1

Clinical Context Considerations

Specific Clinical Scenarios

• In children presenting with opsoclonus-myoclonus-ataxia syndrome, CT chest/abdomen/pelvis with IV contrast or MRI may be helpful for initial diagnosis, though the clinical utility of CT as initial imaging is less clear compared to MIBG scanning. 1
• For infants <6 months with L1 adrenal tumors ≤3.1 cm (if solid) or ≤5 cm (if at least 25% cystic), imaging alone may be sufficient without initial biopsy. 1

Common Pitfalls to Avoid

• Do not rely on ultrasound alone for treatment planning or surgical risk assessment—cross-sectional imaging is mandatory. 1, 2
• Do not assume complete tumor resolution based on ultrasound findings; CT is recommended to evaluate children in whom abdominal disease is thought to have resolved. 3
• Ultrasound's variable and inhomogeneous echo patterns have no value in predicting disease course or response to therapy. 3

Summary of Evidence Quality

The most recent and highest-quality evidence comes from the 2024 NCCN Neuroblastoma Guidelines, which clearly establish that while ultrasound may detect masses, cross-sectional imaging (MRI or CT) is required for comprehensive evaluation. 1 This is supported by older but methodologically sound comparative imaging studies demonstrating ultrasound's limitations in assessing tumor extent and invasive features. 2, 3