Three-year follow-up of human transplanted kidneys by diffusion-weighted MRI and blood oxygenation level-dependent imaging

Abstract

Purpose: To prospectively determine the 3-year stability and potential changes of functional parameters in renal allograft recipients obtained from diffusion-weighted imaging (DWI) and blood oxygenation level-dependent (BOLD) MRI. Materials and Methods: Nine renal allograft recipients underwent DWI and BOLD-MRI twice, once 7 ± 3 months after transplantation, and again 32 ± 2 months after the first MRI. DWI yielded an apparent diffusion coefficient (ADC) and the perfusion contribution (F P). BOLD imaging yielded R2*, providing an estimation of renal oxygenation. Coefficients of variation between (CV b) and within subjects (CV w) were calculated. Results: The parameters were stable after 32 months in eight of the nine patients, who had well-functioning allografts. Mean diffusion values were very similar in the first and second scan. CV w and CV b for ADC values were less than 3.5% and 5.9%, respectively, in cortex and medulla, but were higher for F P (15%-18%). CV w and CV b of R2*were also low (medulla: CV w = 10.8%, CV b = 11.4%; cortex: CV wand CV b = 7.2%). R2*increased significantly (P = 0.035) in cortex but not in medulla, suggesting reduced cortical oxygen content. One subject with decreased glomerular filtration rate demonstrated strongly altered parameters. Conclusion: In the absence of graft dysfunction, DWI and BOLD imaging yield consistent results over 3 years in stable human renal allograft recipients. © 2011 Wiley Periodicals, Inc.