Normal Gallbladder Ejection Fraction
The normal gallbladder ejection fraction (GBEF) is ≥38% when measured using the standardized 60-minute sincalide infusion protocol. 1
Standardized Measurement Protocol
The American Gastroenterological Association recommends a specific protocol for accurate GBEF measurement:
- Sincalide dose: 0.02 μg/kg diluted in saline
- Infusion duration: 60 minutes
- Dynamic imaging: 1 image per minute during infusion
- GBEF calculation formula: (maximum counts - minimum counts) ÷ maximum counts × 100% (all background-corrected)
This standardized approach is critical for reliable results, as variations in methodology can significantly affect measurements. 2, 1
Clinical Interpretation of GBEF Values
- Normal range: ≥38% to 100%
- Abnormal range: <38% (may indicate functional gallbladder disorder)
- No clinical significance is attributed to high normal values 1
Important Considerations When Measuring GBEF
- Infusion rate matters: Rapid infusion of cholecystokinin (CCK) in less than 30 minutes can cause non-physiologic gallbladder contraction and abdominal symptoms unrelated to gallbladder pathology 1
- Standardization is crucial: The lack of standardization between imaging centers has historically been problematic, particularly regarding CCK dose, duration of administration, and normal values 2
- Patient preparation: Patients should fast for at least 4 hours before the test to ensure adequate gallbladder filling
Clinical Applications
GBEF measurement is most commonly used to evaluate patients with suspected functional gallbladder disorder who present with biliary-type pain but have normal gallbladder ultrasound findings (no stones, sludge, or wall thickening). 2, 1
Diagnostic Categories Based on GBEF
- GBEF <38%: Considered biliary dyskinesia/hypokinesia
- GBEF ≥38%: Normal gallbladder function
- GBEF >80%: Some research suggests this may represent biliary hyperkinesia in certain symptomatic patients 3
Pitfalls and Controversies
- The correlation between GBEF values and symptom resolution after cholecystectomy remains controversial
- Some studies suggest that pain provocation during CCK administration and low GBEF may not reliably predict surgical outcomes 4
- Recent research indicates that some patients with very high ejection fractions (>80%) and biliary symptoms may benefit from cholecystectomy, though this remains an evolving area of clinical practice 5, 3
The consensus recommendation from the interdisciplinary panel of the Society of Nuclear Medicine emphasizes the importance of using this standardized protocol to improve reliability and credibility of results when evaluating gallbladder function. 2