ARRS 2022 Abstracts

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E1174. HIDA: Expect the Unexpected
Authors
  1. Tristan Lawson; Wake Forest Baptist Health
  2. Jennifer Schroeder; Wake Forest Baptist Health
Background
Radiology residents will likely encounter nuclear medicine studies for acute care indications during their on-call responsibilities. Common indications for after-hours nuclear medicine examinations include pulmonary embolism, gastrointestinal bleeding, brain death, and acute cholecystitis. In particular, biliary scintigraphy is utilized in the acute care setting for the evaluation of acute cholecystitis, post-operative biliary leaks, and workup of biliary atresia. Notably, at our institution during a 6-month period in 2019 approximately 28% of HIDA scans to evaluate for acute biliary pathology took place after 5PM. Residents who are familiar with classic signs in biliary scintigraphy and who have been exposed to more uncommon but important scintigraphic findings will be better prepared to interpret an after-hours HIDA examination.

Educational Goals / Teaching Points
The goals of this exhibit are to review indications for biliary scintigraphy in the acute care setting; review patient preparation, protocols, and techniques for biliary scintigraphy; illustrate classic signs in biliary scintigraphy via a case-based approach; introduce mimics of classic signs and uncommon biliary pathology that can be diagnosed on HIDA scans; and illustrate how reviewing anatomic imaging in tandem with scintigraphy can help narrow a differential diagnosis.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Classic key imaging findings to be reviewed include non-visualization of the gallbladder, hot rim sign, cystic duct “nubbin” sign, liver scan sign, and reappearing liver sign. Cases will demonstrate classic biliary pathologies including acute cholecystitis, biliary obstruction, biliary atresia, hepatitis, and biliary leak. Less common pathologies including biliary fistula, gallstone ileus, and acalculous cholecystitis will be shown. Emphasis will be placed on reviewing anatomic imaging in conjunction with scintigraphy to avoid diagnostic pitfalls.

Conclusion
Residents must be familiar with acute indications for biliary scintigraphy along with its classic signs and diagnostic pitfalls as a significant portion of these exams occur after hours during on-call responsibilities. This exhibit reviews scan preparation and technique, classic signs, and unusual but important pathologies that residents should be aware of. Correlating scintigraphy with anatomic imaging can help clinch the diagnosis and nail the interpretation of HIDA scans on-call.