Is a HIDA (Hepatobiliary Iminodiacetic Acid) scan with Cholecystokinin (CCK) indicated in suspected gallstone cholecystitis?

HIDA Scan with CCK in Gallstone Cholecystitis: Diagnostic Approach

HIDA scan with CCK is not routinely indicated in gallstone cholecystitis as ultrasound is the recommended first-line imaging modality, but HIDA scan without CCK may be appropriate as a subsequent test if ultrasound is equivocal and clinical suspicion remains high. 1

Initial Diagnostic Approach for Gallstone Cholecystitis

• Ultrasound should be the initial imaging modality for suspected gallstone cholecystitis due to its reasonable accuracy in identifying gallstones, lower cost, portability, and lack of radiation exposure 1
• Ultrasound has a reported sensitivity of 73% (range 32-83%) and specificity of 83% (range 46-88%) for acute cholecystitis 1
• If ultrasound is equivocal but clinical suspicion remains high, further imaging is warranted 1

Role of HIDA Scan in Gallstone Cholecystitis

• HIDA scan has the highest sensitivity and specificity for diagnosing acute cholecystitis compared to other imaging modalities 1
• Studies confirm HIDA scan sensitivity of 84.2-89.3% compared to 67.3% for ultrasound and 59.8% for CT (p=0.017) 1
• Some research suggests even higher sensitivity for HIDA (86%) compared to ultrasound (48%) in diagnosing acute cholecystitis 2

When to Consider HIDA Scan

• HIDA scan should be considered when:
  • Ultrasound findings are equivocal but clinical suspicion for acute cholecystitis remains high 1
  • Other diagnostic possibilities for right upper quadrant pain have been ruled out 1
• HIDA scan demonstrates cystic duct obstruction, which is the hallmark of acute cholecystitis 3

Role of CCK in HIDA Scanning

• CCK (cholecystokinin) is primarily used to stimulate gallbladder contraction to assess gallbladder function 4
• CCK-augmented HIDA scanning is primarily indicated for:
  • Functional gallbladder disorder (biliary dyskinesia) 1
  • Chronic acalculous cholecystitis 1, 5
  • NOT for acute calculous cholecystitis where cystic duct obstruction is already present 1

Limitations and Considerations

• HIDA scan utilization in clinical practice is limited due to required resources and time 1
• Patients must fast for several hours before undergoing a HIDA scan 1
• CCK-HIDA requires standardized protocols for reliable results (0.02 μg/kg sincalide over 60 minutes) 1
• In acute gallstone cholecystitis, the cystic duct is typically obstructed by stones, making gallbladder ejection fraction measurement with CCK unnecessary and potentially misleading 2, 3

Diagnostic Algorithm for Suspected Gallstone Cholecystitis

1. Begin with ultrasound as first-line imaging 1
2. If ultrasound confirms gallstones and signs of cholecystitis, no further imaging is needed 1
3. If ultrasound shows gallstones but is equivocal for cholecystitis:
   • Consider HIDA scan without CCK to assess for cystic duct obstruction 1, 2
   • CT may be considered if complications are suspected (e.g., perforation, abscess) 1
4. If both ultrasound and CT are equivocal, HIDA scan without CCK is recommended 1

Common Pitfalls to Avoid

• Ordering CCK-HIDA for acute gallstone cholecystitis is unnecessary as the primary diagnostic question is cystic duct patency, not gallbladder contractility 2, 3
• Relying on symptom provocation during CCK administration is not a reliable diagnostic indicator for gallbladder disease 1
• Delaying surgical intervention for unnecessary imaging when clinical and ultrasound findings are already diagnostic 1, 6

In conclusion, while HIDA scan is valuable in diagnosing acute gallstone cholecystitis when ultrasound is equivocal, the addition of CCK is not indicated in this setting as it primarily assesses gallbladder contractility rather than the cystic duct obstruction that characterizes acute cholecystitis 1, 2, 3.