Reduced Flow in Delayed Graft Function as Assessed by IVIM Is Associated With Time to Recovery Following Kidney Transplantation.

Background: Delayed graft function (DGF), defined as the need for dialysis in the first week after kidney transplantation, frequently complicates posttransplantation care. The most common cause of DGF is ischemia-reperfusion injury (IRI). To date, no clinical tools can accurately estimate its severity, nor the time required for recovery of kidney function.

Purpose: To investigate if parameters related to directed flow and diffusion of water, as determined by intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI), could be used to differentiate DGF from normal graft function posttransplantation, predict time to recovery from DGF, and hence serve as a surrogate measure of IRI severity.

Study Type: Prospective, cross-sectional cohort study.

Population: Fifty consecutive kidney transplant recipients within 3-10 days posttransplantation at our hospital.

Field Strength/sequence: 3.0T/IVIM-DWI.

Assessment: The following IVIM-DWI parameters were studied: flow-fraction (f), apparent diffusion coefficient (ADC), and total-ADC (ADC ). Mean intrarenal resistive index (R.I.) from Doppler ultrasound was also included for a comparison of IVIM-DWI with the clinical standard of care.

Statistical Tests: Welch's t-test, Spearman's correlation, and linear regression.

Results: f was significantly reduced in DGF compared to non-DGF patients in the cortex, medulla, and whole renal parenchyma (P < 0.05). Time to recovery with respect to MRI correlated negatively with f (P < 0.05; rho = -0.52 (cortex), and -0.65 [parenchyma]), ADC (P < 0.05; rho = -0.59 [cortex], 0.59 [medulla], and -0.59 [parenchyma]) and ADC (P < 0.05; rho = -0.54 [cortex], and -0.52 [medulla]). Whole renal parenchymal f predicted time to recovery relative to MRI (P < 0.05, adjusted r-squared = 0.36). R.I. was significantly different between the groups but did not correlate with time to recovery with respect to MRI (rho = 0.43, P = 0.096).

Data Conclusion: Quantification of renal flow using IVIM-DWI has the potential to serve as a surrogate measure of IRI severity to estimate the degree of and recovery from DGF.

Level Of Evidence: 2 TECHNICAL EFFICACY STAGE: 3.