161 Biliary Atresia

Clinical Presentation

A hepatobiliary scan is requested to help differentiate between biliary atresia and neonatal hepatitis in a 2-week-old infant with extreme lethargy, poor feeding, and a high direct bilirubin level. Sepsis and metabolic disorders have been ruled out.

Fig. 161.1

Fig. 161.2

Technique

• ^99mTc-disofenin is administered intravenously at a dose of 0.05 mCi/kg at the beginning of the acquisition. The minimum dose is 0.25 mCi, and the maximum dose is 3.0 mCi.

• Use a high-resolution or ultra-high-resolution, low-energy, parallel-hole collimator.

• Energy window is 20% centered at 140 keV.

• Imaging time for the initial series is 0.5 minute per frame for 60 minutes. Additional images are obtained at 4 and 24 hours.

• Pre-treatment with phenobarbital is administered at 2.5 mg/kg twice a day for 3 to 5 days before hepatobiliary scintigraphy.

Image Interpretation

Images displayed as 5-minute frames after the injection of ^99mTc-disofenin (Fig. 161.1) demonstrate prompt hepatic uptake of tracer. The high early liver-to-background ratio and the clear definition of the liver boundaries indicate that there is good hepatic extraction of ^99mTc-disofenin, although the prominent renal excretion suggests a mild degree of hepatic dysfunction. Tracer is not identified in the small intestine.

Images at 4 and 24 hours (Fig. 161.2) show no evidence of tracer in the bowel.