Ultrasonography and 99mTc-DISIDA cholescintigraphy in the diagnosis of choledochal cyst in children.

Eighteen children with choledochal cyst have underwent abdominal ultrasonography and 99mTc-DISIDA (di-isopropylphenylcarbamoyl-methylimidodiacetic acid) cholescintigraphy before surgery. All patients had typical sonographic findings of a large cystic mass in the porta hepatis with direct continuity to the biliary system. The gallbladder could be easily recognized and distinguished from the cystic mass in every except one case. Dilatation of the intrahepatic ducts was noted in 12 patients (67%). Coexisting biliary stones were found in 3 patients (17%). On the cholecintigrams, 14 patients (78%) had characteristic findings of a round or ovoid photon-deficient area in the porta hepatis with delayed filling and stasis of the tracer in the same area. Three infants (17%) showed a persistent round photon-defect over the porta hepatis without visualization of gallbladder or bowel radioactivity, which was thought to suggest a choledochal cyst with obstruction. A combination of ultrasonography and cholescintigraphy can provide a very accurate preoperative diagnosis of choledochal cyst.