Multiparametric Renal Magnetic Resonance Imaging: a reproducibility study in renal allografts with stable function
Rebeca Echeverria-Chasco 1 2 , Paloma L Martin Moreno 2 3 , Nuria Garcia-Fernandez 2 3 , Marta Vidorreta 4 , Verónica Aramendia-Vidaurreta 1 2 , David Cano 1 , Arantxa Villanueva 2 5 , Gorka Bastarrika 1 2 , Maria A Fernandez-Seara 1 2
Introduction: Monitoring renal allograft function after transplantation is key for early detection of allograft impairment, which in turn could contribute to preventing the loss of the allograft. Multiparametric renal MRI (mpMRI) is a promising non-invasive technique to assess and characterize renal physiopathology, however, few studies have employed mpMRI in renal allografts with stable function (maintained function over a long time period).
Purpose: To evaluate reproducibility of mpMRI in transplanted patients and to characterize normal values of the measured parameters. To estimate labeling efficiency of PCASL in the infrarenal aorta, using numerical simulations considering experimental measurements of aortic blood flow profiles.
Methods: Subjects: Twenty transplanted patients with stable kidney function, maintained over one year. MRI protocol: Pseudo-Continuous Arterial Spin Labeling (PCASL), Intravoxel Incoherent Motion (IVIM) and T1 inversion recovery. Phase-contrast to measure aortic blood flow.
Data analysis: renal blood flow (RBF), diffusion coefficient D, pseudo-diffusion coefficient D*, flowing fraction f and T1 maps were calculated and mean values were measured in the cortex and medulla. PCASL labeling efficiency was estimated from Bloch equations simulation.
Statistical analysis: Reproducibility was assessed with the within-subject coefficient of variation, intra class correlation coefficient and Bland-Alman analysis. Correlations were evaluated using Pearson correlation coefficient. Significance level: P < 0.05.
Results: Cortical reproducibility was very good for T1, D, RBF, moderate for f and low for D*, while medullary reproducibility was good for T1 and D. Significant correlations in the cortex between RBF and f (r=0.66), RBF and eGFR (r=0.64) and D* and eGFR (r=-0.57) were found.
Conclusion: Normal values of the measured parameters employing mpMRI protocol in transplanted kidney patients with stable function were characterized and the results showed good reproducibility of the techniques.