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The evaluation of paediatric renal transplants using resistive index and renal blood flow
M M Fitzpatrick1, F V Gleeson, R de Bruyn
1Department of Nephrology, Institute of Child Health, London, UK.
Insights
Renal blood flow (RBF) measured by DTPA isotope renography accurately reflects kidney transplant dysfunction in children. Resistive index (RI) from Doppler sonography showed no significant changes during rejection episodes or acute tubular necrosis.
Area of Science:
- Pediatric Nephrology
- Transplant Surgery
- Diagnostic Imaging
Background:
- Post-renal transplant complications in children require accurate monitoring.
- Non-invasive imaging techniques are crucial for assessing graft health.
Purpose of the Study:
- To compare the efficacy of duplex Doppler sonography (Resistive Index - RI) and DTPA isotope renography (Renal Blood Flow - RBF) in evaluating pediatric renal transplant dysfunction.
- To determine which parameter better reflects graft status.
Main Methods:
- Serial duplex Doppler sonography and DTPA isotope renography were performed on six pediatric renal transplant recipients (1.3-6.9 years).
- Resistive Index (RI) and Renal Blood Flow (RBF) were calculated and correlated with clinical status and plasma creatinine levels.
- Six rejection episodes and two graft losses due to renal venous thrombosis were analyzed.
Main Results:
- A significant decrease in RBF correlated with rising plasma creatinine during rejection episodes.
- No significant changes in RI were observed during rejection episodes or acute tubular necrosis.
- Graft loss due to renal venous thrombosis was associated with undetectable RBF.
- RBF improved as graft function was established after acute tubular necrosis.
Conclusions:
- Renal blood flow (RBF) measured by DTPA isotope renography is a more accurate indicator of pediatric renal transplant dysfunction than the resistive index (RI).
- RI may not be a sensitive marker for rejection or acute tubular necrosis in this population.
Abstract:
Six children (aged 1.3-6.9 years) were examined with serial duplex Doppler sonography and diethylenetriaminepenta-acetic acid (DTPA) isotope renography in the post-renal transplant period. The resistive index (RI) was derived from sonographic studies and the renal blood flow (RBF) calculated from the isotope scans. The clinical status of the child and the corresponding plasma creatinine level were assessed together with these two parameters. The RIs ranged from 40% to 100% and the RBF from 0% to 16.8%. There were six rejection episodes in four patients. A significant fall in RBF mirrored a rise in plasma creatinine on each occasion, but there was no significant change in RI recorded. There were two graft losses, both associated with renal venous thrombosis. In both cases no significant RBF could be detected on DTPA renography. In one patient, the RBF remained low throughout a period of primary non-function associated with acute tubular necrosis, and increased as primary function was established and the plasma creatinine fell. Throughout this period there was no significant change in the RI. From our preliminary data RBF reflects graft dysfunction more accurately than does the RI.