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

Abstract

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. 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. 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(w) and 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. In the absence of graft dysfunction, DWI and BOLD imaging yield consistent results over 3 years in stable human renal allograft recipients.