What is the role of Fibroscan (Fibrosis Scan) in assessing liver fibrosis and steatosis in pediatric patients with suspected or confirmed liver disease, such as non-alcoholic fatty liver disease (NAFLD)?

Role of FibroScan in Pediatric Liver Disease Assessment

FibroScan (transient elastography) serves as a validated non-invasive tool for assessing liver fibrosis in children with chronic liver disease, though it has not been sufficiently validated to replace liver biopsy for definitive diagnosis or treatment decisions in pediatric NAFLD. 1

Current Guideline Position on FibroScan in Children

The American Association for the Study of Liver Diseases explicitly states that transient elastography (TE), along with MR elastography and acoustic radiation force impulse imaging, has not been sufficiently validated to serve as a sufficient replacement for tissue sampling in pediatric patients. 1 This represents a critical distinction from adult practice, where FibroScan has more established diagnostic thresholds and clinical utility.

When FibroScan Should Be Considered in Children

Despite limited validation, FibroScan can be useful in specific pediatric scenarios:

• Children with suspected advanced fibrosis or cirrhosis where identifying high-risk patients could guide the decision for liver biopsy rather than subjecting all children to invasive procedures 1

• Post-liver transplant monitoring where FibroScan demonstrated good diagnostic accuracy (AUROC 0.865) for detecting significant graft fibrosis (≥F2), with a cutoff of 5.6 kPa showing 75% sensitivity and 95.8% specificity 2

• Cystic fibrosis-associated liver disease (CFLD) where liver stiffness was significantly elevated in patients with clinical CFLD (11.2 kPa vs 5.1 kPa in controls), providing an objective screening measure 3

• Serial monitoring of known chronic liver disease to track progression and potentially reduce the frequency of protocol liver biopsies, particularly in transplant recipients 2

Technical Feasibility in Pediatric Populations

FibroScan is technically feasible in children, with success rates comparable to adults when appropriate equipment is used:

• Standard probe limitations: The original adult probe had limitations in smaller children, prompting development of a pediatric-specific probe (S probe) for children and slender patients 4

• Success rates: Studies demonstrate FibroScan can be successfully performed in children as young as 5 years old, with only 1 of 116 children unable to complete the examination in one feasibility study 4

• Technical validity requirements remain the same: ≥10 successful measurements, success rate ≥60%, and interquartile range <30% of median value 5

Disease-Specific Performance Data

Pediatric NAFLD/NASH

The evidence for FibroScan in pediatric NAFLD is mixed and requires cautious interpretation:

• Correlation with histology: LSM showed significant correlation with Ishak fibrosis stages in NAFLD patients, though the correlation was weaker (r=0.47) compared to non-NAFLD liver diseases 6

• Predicting advanced fibrosis: LSM adequately predicted Ishak stages F0-2 versus F3-F6 with AUROC of 0.73 in all patients and 0.77 in non-NAFLD patients 6

• Steatosis assessment: Controlled Attenuation Parameter (CAP) strongly predicted histologic steatosis grade (r=0.84, AUROC 0.98), making it highly reliable for quantifying hepatic fat 6

• FAST score in children: The FibroScan-AST (FAST) score showed acceptable discriminatory ability for significant liver disease (AUROC 0.75), with a cutoff ≥0.67 having 89% sensitivity but only 62% specificity 6

• Practical cutoff for screening: In Korean children with obesity, LSM >5.5 kPa identified those with significantly higher transaminases and metabolic dysfunction 7

Non-NAFLD Chronic Liver Diseases

FibroScan performs better in non-NAFLD pediatric liver diseases:

• Cirrhosis detection: For diagnosing cirrhosis across various pediatric liver diseases, FibroScan achieved AUROC of 0.88, superior to Fibrotest (0.73) and APRI (0.73) 4

• Correlation with disease severity: LSM correlated significantly with clinical and biochemical parameters of chronic liver disease, showing stronger associations than competing non-invasive markers 4

Critical Limitations and Pitfalls

Insufficient Validation for Treatment Decisions

The most important caveat is that current guidelines do not support using FibroScan alone to make treatment decisions in pediatric NAFLD. 1 The AASLD specifically recommends that a liver biopsy to establish a diagnosis of NASH should be obtained before starting children on pharmacological therapy for NASH. 1

Disease-Specific Threshold Differences

• Pediatric thresholds differ from adults: The optimal cutoffs for fibrosis stages in children have not been definitively established and appear to vary by underlying liver disease etiology 1

• Cholestatic vs. hepatocellular diseases: Thresholds for biliary atresia are substantially different and often much higher than those for hepatocellular diseases like HCV and NAFLD 1

Technical Considerations

• Obesity remains a challenge: Even with the XL probe, obesity can limit examination quality in children, similar to adults 1

• Age-specific reference ranges needed: Normal liver stiffness values vary by age in children, requiring age-specific cutoffs for interpretation 3

• Fasting requirements: Children should fast for at least 3-4 hours before examination to avoid falsely elevated measurements from increased hepatic blood flow 5

Practical Algorithm for Using FibroScan in Children

Step 1: Determine if FibroScan is Appropriate

Use FibroScan when:

• Child has confirmed chronic liver disease requiring fibrosis staging
• Monitoring post-transplant graft fibrosis
• Screening for CFLD in cystic fibrosis patients
• Serial monitoring to reduce biopsy frequency in known disease

Do NOT rely solely on FibroScan when:

• Diagnosis is uncertain and multiple etiologies are possible 1
• Considering pharmacological therapy for NASH (biopsy required) 1
• Child is very young or not overweight with fatty liver (test for monogenic causes first) 1

Step 2: Ensure Proper Technique

• Use pediatric S probe for children <12 years or those with slender body habitus 4
• Ensure 3-4 hour fasting period 5
• Obtain ≥10 valid measurements with IQR <30% of median 5
• Avoid examination during acute hepatitis or active inflammation 5

Step 3: Interpret Results in Clinical Context

For NAFLD:

• LSM <5.5 kPa: Low probability of significant fibrosis, consider metabolic management and surveillance 7
• LSM 5.5-8.0 kPa: Indeterminate zone, correlate with clinical risk factors and consider biopsy if treatment contemplated 7, 6
• LSM >8.0 kPa: High probability of significant fibrosis, strongly consider biopsy before treatment decisions 6

For post-transplant monitoring:

• LSM <5.6 kPa: Low probability of significant graft fibrosis (F≥2), continue routine surveillance 2
• LSM ≥5.6 kPa: Consider protocol biopsy to confirm fibrosis and guide management 2

For CFLD:

• Use age-specific cutoffs from control populations 3
• Elevated LSM should prompt comprehensive hepatology evaluation 3

Step 4: Integration with Other Assessments

• Always combine with clinical assessment: Transaminases, platelet count, albumin, INR, and imaging findings 4
• Consider complementary scores: ELF score has shown promise in predicting fibrosis in children with NAFLD, though validation studies were small 1
• CAP for steatosis quantification: Highly accurate for grading hepatic steatosis and can guide metabolic interventions 6

Key Takeaway for Clinical Practice

FibroScan is a useful adjunctive tool in pediatric hepatology but should not replace liver biopsy when definitive diagnosis or treatment decisions are needed, particularly in NAFLD. 1 Its greatest utility lies in serial monitoring of known disease, post-transplant surveillance, and identifying high-risk patients who warrant invasive evaluation. The lack of validated pediatric-specific cutoffs across different liver diseases remains a significant limitation that clinicians must recognize when interpreting results.