From the Guidelines
A HIDA scan is considered a reasonable option for diagnosing acute cholecystitis, particularly when CT is equivocal, due to its status as the gold standard for this condition, despite requiring a patient to fast for several hours beforehand. According to the 2024 clinical practice guideline update by the Infectious Diseases Society of America 1, HIDA scans are a viable choice for subsequent imaging studies beyond CT, especially when acute cholecystitis is suspected. The benefits of HIDA scans include their ability to accurately diagnose acute cholecystitis and their lower cost compared to MRI/MRCP. However, it's essential to consider the need for patients to fast before undergoing a HIDA scan and the potential for radiation exposure.
Some key points to consider when deciding on a HIDA scan include:
- The patient's ability to fast for several hours before the test
- The potential benefits of HIDA scans in diagnosing acute cholecystitis, particularly when other imaging modalities are inconclusive
- The comparison with other imaging options, such as MRI/MRCP, which may provide a clearer picture of surrounding structures but are more costly
- The importance of considering the risk-to-benefit ratio of radiation exposure, especially in children and pregnant individuals, as outlined in the guideline update 1
In terms of patient preparation and the procedure itself, patients typically need to fast for 4-6 hours before undergoing a HIDA scan, and certain medications may need to be temporarily stopped. The test involves injecting a radioactive tracer into the bloodstream, which is then tracked by a special camera as it flows through the biliary system. The procedure usually takes about 1-2 hours, and patients may be administered a medication called cholecystokinin (CCK) to stimulate gallbladder contraction. Overall, HIDA scans provide valuable diagnostic information, especially in cases where other imaging modalities are inconclusive, as noted in the guideline update 1.
From the Research
Hida Scan Overview
- A Hida scan, also known as a hepatobiliary scan, is a nuclear medicine test that uses a small amount of radioactive material to evaluate the function and structure of the gallbladder and bile ducts 2.
- The scan involves injecting a radioactive tracer, such as 99mTc-HIDA, into the bloodstream, which is then taken up by the liver and excreted into the bile ducts and gallbladder 2.
Clinical Applications
- Hida scans can be used to diagnose various hepatobiliary diseases, including acute and chronic cholecystitis, and to assess biliary drainage in patients with jaundice 2.
- The scan can also help identify obstruction of the cystic duct or common bile duct, and can be used to evaluate the function of the gallbladder and bile ducts in patients with surgically altered biliary tract anatomy 2.
Utilization and Overuse
- Despite the availability of clinical guidelines for diagnosing acute cholecystitis, Hida scans are often overutilized, particularly in patients who meet clinical criteria for cholecystitis based on the Tokyo guidelines 3.
- A study found that over half of patients who met the Tokyo guidelines for suspected or definite cholecystitis underwent a Hida scan, indicating overutilization 3.
- The overuse of Hida scans can increase healthcare costs and delay care, and it is recommended that these scans be reserved for cases with inconclusive ultrasound results but high clinical suspicion for cholecystitis 3.