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Introduction:
In pediatric kidney transplantation, adequate perfusion of adult-sized grafts demands significant hemodynamic changes in small recipients. Hypoperfusion can shorten graft survival by loss of kidney mass and function, especially in donor-recipient size mismatch. In order to adequately perfuse the transplanted adult-sized kidney, young recipients are hypothesized to develop a supraphysiological hemodynamic state. Our primary objective is to enhance knowledge and insight in hemodynamic responses after pediatric kidney transplantation with a living, adult donor. By comparing Magnetic Resonance – Arterial Spin Labeling (MR-ASL) with transabdominal and intra-operative ultrasound (US), our secondary goal is investigating the reliability of non-invasive techniques in monitoring donor kidney perfusion after transplantation.
Material and methods:
Twenty children (including donors) with a maximum age of 15 and a maximum weight of 40kg will be included in this prospective clinical pilot study with 12 months of follow-up. Peri-operative hemodynamics are monitored closely, including cardiac output measurements. We measured volume of the kidney graft (MR), whole organ kidney perfusion (MR-ASL) and afferent blood flow (US and MR) before, during and 6 months after transplantation. We present the first three patients with complete series of imaging in follow up.
Results:
MR-ASL perfusion imaging yields good quality images and reproducible perfusion values. Kidney graft volumetrics and perfusion showed a decrease after transplant, and a subsequent compensatory increase at 6 months. Afferent flow measurements comparing US and MR are corresponding, and in line with our hypotheses.
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Mean graft volume (cm3)
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Mean graft perfusion (ml/min)
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1. Pre-transplant
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306
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407
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2. Post-transplant
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202
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(↓34%)
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161
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(↓60%)
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3. FU 6 months
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226
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(↑12%)
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233
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(↑45%)
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Conclusions:
In pediatric kidney transplantation with an adult living donor, graft volume and perfusion decreased considerably after transplantation and recovered partially after 6 months. Complementing current monitoring techniques, MR-ASL proves to be a feasible non-invasive peri-operative imaging technique, yielding good quality images and reproducible perfusion values.
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