The significance of non-invasive advanced MRI techniques in evaluation of renal allograft function

Abstract

Uvod: Perfuzija predstavlja protok krvi u kapilarnom koritu koji određuje dopremanje nutrijenata i kiseonika tkivu, a u bubrezima reguliše stepen glomerulske filtracije (GFR) kao centralnu meru bubrežne funkcije. Razvoj neinvazivne i pouzdane metode za merenje bubrežne perfuzije koja bi oslikavala GFR bi značajno unapredila pravovremeno otkrivanje oštećenja alografta. Cilj: Utvrđivanje kod kojih pedijatrijskih pacijenata alograft ima oštećenu funkciju merenjem kortikalne bubrežne perfuzije (cRBF), uz upoređivanje sa perfuzijom zdravih kontrola korišćenjem tehnike obeležavanja spinova u arterijskoj krvi magnetnom rezonancom (ASL-MRI). Metodologija: Kod 20 pacijenata sa alograftom i 20 zdravih kontrola je izveden ASL-MRI u cilju kvantifikacije cRBF na parametarskim mapama. cRBF je korelirana sa izračunatim GFR kod alografta i upoređivana među grupama pacijenata sa očuvanom (GFR≥60 mL/min/1.73m2) i oštećenom (GFR<60 mL/min/1.73m2) funkcijom, a zatim i sa zdravim kontrolama. Rezultati: cRBF kod pacijenata sa alograftom je bila u rasponu između 85 i 335ml/100gr/min (prosečno 190.05 ± 67.62 mL/100 g/min). Prosečna cRBF kod pacijenata sa dobrom funkcijom je bila značajno višа nego kod pacijenata sa lošom (225.91±64.38mL/min/100g vs. 146.22±41.84mL/min/100g, p=0.005), uz značajnu korelaciju sa GFR kod svih pacijenata (r=0.64, p=0.002). Kod zdravih se prosečan cRBF razlikovao u odnosu na pacijente sa oštećenom funkcijom (322.00±121.36vs. 146.22±41.84ml/100gr/min, p=0.002) dok se nije razlikovao u odnosu na pacijente sa stabilnom funkcijom (322.00±121.36vs.225.91±64.38ml/100gr/min, p=0.056). Zaključak: Neinvazivno izmerena kortikalna bubrežna perfuzija ASL-MRI metodom se razlikuje između pacijenata sa očuvanom i oštećenom funkcijom alografta, sa kojom značajno korelira.Background: Perfusion represents a blood flow at the level of the tissue capillary bed and determines the delivery of nutrients and oxygen, while in kidneys regulates glomerular filtration rate (GFR), as a central measure of renal function. The development of a non-invasive and reliable method for renal perfusion estimation that would reflect GFR would significantly improve on-time identification of potential allograft injury. Aim: Discrimination of renal allografts with impaired function by measuring cortical renal blood flow (cRBF) in pediatric patients, as well as a comparison with cRBF values of healthy controls using magnetic resonance imaging arterial spin labelling (ASL-MRI). Methods: We performed ASL-MRI in 20 allograft patients and 20 healthy controls to calculate cRBF on parameter maps. It was correlated to calculated GFR in allografts and compared between patient groups with good (GFR≥60 mL/min/1.73m2) and impaired allograft function (GFR<60 mL/min/1.73m2) as well as with healthy controls. Results: cRBF in patient group ranged between 85 and 335 mL/100 g/min (mean 190.05 ± 67.62 mL/100 g/min). Mean cRBF in patients with good allograft function was significantly higher than in patients with impaired function (225.91±64.38 vs. 146.22±41.84 mL/min/100g, p=0.005), showing a highly significant correlation with GFR in all subjects (r=0.64, p=0.002). In healthy controls mean cRBF was significantly higher than in patients with poor allograft function (322.00±121.36 vs. 146.22±41.84 ml/100gr/min, p=0.002) and showed no difference to patients with stable function (322.00±121.36 vs. 225.91±64.38 ml/100gr/min, p=0.056). Conclusion: Cortical perfusion as non-invasively measured by ASL-MRI differs between patients with good and impaired allograft function and correlates significantly with its function

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