IS Case 603: Biliary atresia
Imaging Sciences URMC 2010
Publication Date: 2011-11-17
History
The patient is a 4-week-old female with persistently elevated bilirubin levels and abnormal LFTs (current: total bilirubin 6.9, direct bilirubin 5, ALT 121, ALK 541, GGT 966).
Findings
There is prompt concentration of the radiotracer in the liver, with persistent radiotracer activity in the cardiac blood pool at 30 minutes (Fig. 1A). The gallbladder is not visualized at any time during the examination (Fig. 1A-C). The passage of the radiotracer into the extrahepatic biliary system and bowels is not identified at any time following injection with radiotracer (Fig. 1A-C). No significant radiotracer uptake is noted in the kidneys (Fig. 1A-C). Trace levels of the radiotracer are identified in the bladder and diaper on the 24 hour scan, consistent with urine contamination (Fig. 1C). In the setting of persistently abnormal LFTs and elevated bilirubin levels, failure to visualize the biliary system or small bowel radiotracer accumulation by 24 hours is consistent with the clinical diagnosis of biliary atresia.
Discussion
Biliary atresia, defined as the lack of patent extrahepatic bile ducts, is the most common cause of cholestasis in infants younger than 3 months [1]. The disease is defined by inflammation and sclerosis of the intra and extrahepatic bile ducts causing ductal luminal obliteration and eventual biliary cirrhosis and obliteration of the biliary tree [1]. The clinical forms of biliary atresia include the perinatal type (65%-85%) and the embryonic or fetal type (15-35%). The perinatal type has postnatal onset of cholestasis, no associated congenital anomalies, and the bile duct remnants are present [1]. The embryonic or fetal type has early onset of cholestasis, no bile duct remnants, and associated congenital anomalies [1].
Diagnosis is dependent on clinical, laboratory, and radiologic tests, with the definitive diagnosis made by showing fibrosis of the extrahepatic biliary tree on surgical exam. Radiologically, scintigraphy, abdominal ultrasound, duodenal bile aspiration, and liver biopsy are the main methods for evaluating the biliary tree. In the current study, scintigraphy was utilized visualize the liver and bile duct system. 99mTc-iminodiacetic acid (IDA) was used in the current study to visualize the liver uptake and clearance of the radiotracer from the blood pool [2]. In this infant, the extrahepatic ducts, gallbladder, and small bowel transit were not identified during the course of the study.
References
- Narkewicz MR. Biliary atresia: an update on our understanding of the disorder. Curr Opin Pediatr. 2001 Oct;13(5):435-40. PMID: 11801889
- Mettler FA, Guiberteau MJ. Essentials of Nuclear Medicine Imaging, 5th ed. Saunders Elsevier, Philadelphia. 2006.
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