ABSTRACT
The aim of this study was to assess the diagnostic sensitivity and specificity of hepatobiliary scintigraphy using a 99mTc-HIDA compound to differentiate intrahepatic cholestasis from extrahepatic forms during the first months of life. The tracer used was acid N-(2,6)-diethylacetanylido-iminodiacetic (diethyl-HIDA) with almost exclusively biliary excretion and a high concentration of radioactivity in the bile. Each neonate was injected with 0.5 mg/kg i.v. of the compound marked with a dose of 99mTc equivalent to 80-100 microCi/kg. Scintigraphic recordings were carried out every 10' for the first hour and further controls were performed at 2, 3, 4, 8 and 24 hours. Scintiphotos were obtained using a Polaroid scintillation camera, PHO Gamma V. Fifty-four patients were included in the study (34 males and 20 females) aged between 4 days and 3 months old. All patients were clinically suspected of pathologies involving the hepatobiliary tract. All cases were affected by persistent jaundice (total bilirubin between 1.8 and 39.6 mg%) with predominantly direct bilirubin (range 1.5-26.2 mg%), acholic feces and hyperchromic urine. Hepato-biliary scintigraphy revealed an intestinal excretion of tracer in 31 out of the 54 neonates examined, excluding the presence of an extrahepatic obstruction of the biliary tract. On the other hand, only 13 out of 23 cases in which no enteric excretion of the tracer was observed, was the final diagnosis one extrahepatic cholestasis. Scintigraphic tests therefore showed a 100% sensitivity associated with a specificity of only 56.52%. This demonstrates that the finding of tracer in the intestine is pathognomonic of the permeability of extrahepatic biliary ducts and that biliary atresia can be ruled out. On the contrary, the absence of the intestinal excretion of the tracer is nor constantly associated with biliary atresia. This study has confirmed this finding in 10 cases of intrahepatic cholestasis (4 hypoplasias of the intrahepatic biliary tract, 3 thick bile syndromes, 3 cases of hepatitis due to cytomegalovirus). In conclusion, the Authors state that hepato-biliary scintigraphy represents a straightforward and non-invasive diagnostic method which enables the permeability of the biliary tract to be assessed in subjects with jaundice.
