Role of Hepatobiliary Scintigraphy in the Management of Paediatric Liver Transplantation

Stenosis of the bilio-digestive anastomosis is a frequent (up to 20%) and dreaded complication of paediatric liver transplantation, often leading to recurrent cholangitis and eventually to graft failure. Diagnosis is particularly difficult when subocclusion results in progressive parenchymal damage without bile ducts dilatation. This study evaluates the role of hepatobiliary scintigraphy (HBS) using Iminodiacetic Acid derivatives in the management of this group of patients. Patients and methods: Twenty-six children with suspected biliary stenosis (sex F=10, M=16, age: mean=17 y) were enrolled in the study, following paediatric orthotopic liver transplantation (age at tranplantation: mean=6 yrs, follow-up duration: mean=8.5 yrs). The clinical workout included standard hepatic biochemical markers and ultrasound evaluation. Hepatobiliary scintigraphy (99mTc-BROMIDA, weight scaled dose using 185 MBq adult reference dose) was performed acquiring dynamic images (LEHR collimator, 128x128 matrix, 30 sec/frame) for 60 min. Timeactivity curves were obtained, for each patient, from region of interest (ROI) drawn respectively on liver parenchyma, avoiding biliary tree, and on biliary reservoir (Roux loop). Time-to-maximum (Tmax) and half-time (T50) were calculated for liver parenchyma and biliary reservoir. Results: Based on the distribution of the four numerical parameters two sub-groups were identified: group A (5 pts.) showed a marked delay in tracer excretion (parenchymal T50 42+/-15 minutes, loop-Tmax 16+/- 9 minutes, loop-T50 52+/-7 minutes) compared to group B (parenchymal T50 21+/-10 minutes p<0.05, loop-Tmax 9+/-5 minutes p<0.001, loop-T50 31+/-12 minutes p<0.01, Mann-Whitney test). No biliary dilatation was detectable in both groups on ultrasound and only 2 patients from group A showed a slight increase in bilirubin levels (27 and 55 umol/L), whereas ≥ GT levels were out of the normal range in 5/5 patients of group A and 9/21 of group B. The five patients of group A underwent percutaneous cholangiography, which showed in all of them a biliary stenosis and in 4/5 patients a biopsy was performed. The histopathology did not show any specific sign of biliary obstruction, but only unspecific infiltration pattern. Surgical correction has been planned in every case and in three of them has been already performed, with normalization of the scintigraphic pattern. The clinical follow-up of group B patients did not detect any sign of progression. Conclusion: The study confirm that hepatobiliary scintigraphy can be useful in the follow-up of paediatric liver transplantation, particularly when sub-clinical biliary stenosis is suspected.