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Hepatobiliary scintigraphy is a diagnostic nuclear medicine procedure that uses radiotracers to evaluate the biliary system and indirectly, the liver. The radiotracer used is iminodiacetic acid (IDA) or a variant. This is administered intravenously, bound to albumin, transported to the liver, and excreted into the biliary system. The utility of hepatobiliary IDA (HIDA) scan is that the radiotracer follows the bilirubin metabolic pathway and excretion into the bile ducts and thus is especially helpful in identifying gall bladder pathology. This activity describes the indications for the hepatobiliary iminodiacetic acid scan and highlights the role of the interprofessional team in the management of patients with suspected gall bladder disease. Objectives: Describe how gallstones form. Explain how a hepatobiliary iminodiacetic acid scan is performed. Explain what the hepatobiliary iminodiacetic acid scan might reveal. Employ interprofessional team strategies for enhancing care coordination and communication to advance the evaluation and management of gall bladder disease and improve patient outcomes. Access free multiple choice questions on this topic.

Hepatobiliary scintigraphy is a diagnostic nuclear medicine procedure which uses radiotracers to evaluate the biliary system and also, indirectly, the liver. The radiotracer used is iminodiacetic acid (IDA) or some close variant which is administered intravenously, bound to albumin, transported to the liver, and excreted into the biliary system. The utility of hepatobiliary IDA or HIDA scan is that the radiotracer follows the bilirubin metabolic pathway and excretion into the bile ducts.[1][2] Thus, in the case of acute cholecystitis which is largely caused by obstruction of the cystic duct, radiotracers cannot enter the gallbladder which is demonstrated by gallbladder non-visualization. The hallmark of chronic cholecystitis is decreased ejection fraction measured objectively with maximum gallbladder radiotracer signal and minimum radiotracer signal after administration of sincalide which contracts the gallbladder. Biliary atresia or distal biliary obstruction is demonstrated by the absence of radiotracer in the duodenum. Extrabiliary radiotracer signifies biliary leak, etc.[3] Ultrasound has been the primary modality for initially assessing gallbladder pathology. In suspected acute cholecystitis sonographic findings (gallbladder wall thickening, cystic duct dilation, pericholecystic fluid) are secondary and take time to develop. A HIDA scan demonstrates cystic duct obstruction which is the underlying primary event and immediately apparent. Scintigraphy is unlikely to supplant ultrasound as the initial modality for right upper quadrant pain because ultrasound is readily available, is portable, fast, requires minimal patient preparation, avoids ionizing radiation, and may offer alternative diagnoses.

During a typical HIDA scan, the patient exposure will be 3-4 mSv of radiation which is roughly the amount of background radiation experienced in one year. For reference, a chest x-ray exposes the patient to 0.001 mSv of radiation while a computed tomography of the head requires 1-5 mSv.[7]

Ordering a HIDA requires the nuclear radiologist to review the patient's previous imaging modalities, surgical history, current medications, laboratory data, and suspected diagnosis. The imaging team must coordinate with the patient and the patient's provider to ensure that a sufficient period has passed since the most recent meal. Additionally, coordination of risk assessment and possible medication cessation must occur between the nurse practitioner, internist, and primary care provider to optimize the HIDA scan interpretation. [Level V]