Efficiency of diffusion-weighted MRI-apparent diffusion coefficient measurements with shear wave elastography in kidney transplanted patients

Microvascular changes cause renal fibrosis over time, and increased fibrosis leads to allograft dysfunction. In this study, we aimed to assess renal allograft fibrosis using shear wave elastography (SWE), a contemporary, noninvasive imaging technique. Additionally, we sought to evaluate perfusion and microvascular distribution through diffusion-weighted magnetic resonance imaging (MRI) within the same graft. By combining these 2 modalities, we sought to enhance the detection of allograft dysfunction. Eighty-seven kidney transplant recipients (33 females, 17-72 years; 52 males, 15-75 years) were prospectively enrolled. In the prospective study, after diffusion MRI of the transplanted kidney was performed, apparent diffusion coefficient (ADC) values were obtained from the renal cortex. Moreover, stiffness was measured via simultaneous SWE from the cortex of the same graft, and the correlation of both methods with the estimated glomerular filtration rate (eGFR) and several renal biomarkers was compared. Compared with the eGFR > 60 mL/min group, mean SWE values were significantly higher at the upper, middle, and lower poles, and ADC values were significantly lower in the eGFR ≤ 60 mL/min group. ADC values were significantly associated with the presence of proteinuria; patients with spot urine protein creatinine ratio (SUPC) > 300 mg/g had lower ADC values than those with ≤ 300 mg/g. Receiver operating characteristic analysis for ADC (area under curve = 0.825) differentiated the 2 eGFR groups with 82.8% sensitivity and 76.8% specificity. The results of this study suggest that SWE and diffusion-weighted MRI may help detect the fibrosclerotic changes that are characteristic of renal dysfunction in transplant patients. The results also suggest that SWE tend to have a better capacity in capturing fibrosis compared to than diffusion-weighted MRI, though the latter seems better at capturing proteinuria.