Evaluation of the blood-oxygen-level-dependent (BOLD) sequence with 3 Tesla device in renal transplant patients in the assessment of early allograft disfunction, correlated with biopsy.

Guilherme Falleiros Mendes,Priscila Mina Falsarella,Rodrigo Gobbo Garcia,Liana Guerra Sanches,Ronaldo Hueb Baroni

doi:10.31744/einstein_journal/2021ao6069

Guilherme Falleiros Mendes, Priscila Mina Falsarella + Show 3 more

Open Access

https://doi.org/10.31744/einstein_journal/2021ao6069

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Abstract

ABSTRACTObjective To evaluate the ability of blood-oxygen-level-dependent (BOLD) magnetic resonance imaging at 3 Tesla to measure tissue oxygen bioavailability based on R2* values, and to differentiate between acute tubular necrosis and acute rejection compared to renal biopsy (gold standard).Methods A prospective, single-center study, with patients submitted to renal transplantation between 2013 and 2014, who developed graft dysfunction less than 4 weeks after transplantation. All patients were submitted to abdominal magnetic resonance imaging at 3 Tesla using the same protocol, followed by two BOLD sequences and kidney biopsy.Results Twelve male (68.75%) and three female (31.25%) patients were included. A total of 19 percutaneous renal biopsies were performed (four patients required a second biopsy due to changes in clinical findings). Pathological findings revealed ten cases of acute tubular necrosis, four cases of acute rejection, and five cases with other (miscellaneous) diagnoses. Comparison between the four groups of interest failed to reveal significant differences (p=0.177) in cortical R2* values, whereas medullary R2* values differed significantly (p=0.033), with lower values in the miscellaneous diagnoses and the acute tubular necrosis group.Conclusion BOLD magnetic resonance imaging at 3 Tesla is a feasible technique that uses indirect tissue oxygen level measurements to differentiate between acute rejection and acute tubular necrosis in renal grafts.

Highlights

Kidney transplantation is the ideal renal replacement therapy for chronic renal failure, with surgical outcomes and graft durability having improved significantly in recent years.[1]
Oxygen concentration is slightly higher in the cortex than in the medulla, and this difference that can be detected using BOLD magnetic resonance imaging (MRI).[5]. Patients with acute kidney allograft rejection show a significant increase in oxygen concentration in the medulla, seen as a decrease in the R2* signal.[5,6]
This study examined the applicability of BOLD MRI at 3 Tesla (3T) to assess kidney function following kidney transplantation, based on comparative analysis of patients with and without kidney changes

Summary

Introduction

Kidney transplantation is the ideal renal replacement therapy for chronic renal failure, with surgical outcomes and graft durability having improved significantly in recent years.[1]. The effectiveness of blood-oxygen-level-dependent (BOLD) magnetic resonance imaging (MRI) in assessing pathological conditions, such as renal artery stenosis, ureteral obstruction, diabetic nephropathy, AR and ATN, has been demonstrated in many recent studies.[4]. BOLD MRI is a noninvasive modality that evaluates tissue oxygen concentration In this technique, the paramagnetic effect of deoxyhemoglobin acts as an endogenous contrast agent.[5] When tissue oxygen concentration drops, tissue deoxyhemoglobin concentration increases, leading to signal reduction in the T2* sequence and resultant increase in the apparent relaxation rate R2* (1/T2*).(5). Few studies have used 3 Tesla (3T) magnets, which allow for higher spatial resolution and better visual differentiation between the renal cortex and medulla.[1,5,7,8]

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