Detection of renal allograft fibrosis with MRI: arterial spin labeling outperforms reduced field-of-view IVIM

Objective To compare the value of reduced field-of-view (FOV) intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) and arterial spin labeling (ASL) for assessing renal allograft fibrosis and predicting long-term dysfunction. Methods This prospective study included 175 renal transplant recipients undergoing reduced FOV IVIM DWI, ASL, and biopsies. Renal allograft fibrosis was categorized into ci0, ci1, ci2, and ci3 fibrosis according to biopsy results. A total of 83 participants followed for a median of 39 (IQR, 21-42) months were dichotomized into stable and impaired allograft function groups based on follow-up estimated glomerular filtration rate. Total apparent diffusion coefficient (ADC(T)), pure diffusion ADC, pseudo-perfusion ADC, perfusion fraction f from IVIM DWI, and renal blood flow (RBF) from ASL were calculated and compared. The area under the receiver operating characteristic curve (AUC) was calculated to assess the diagnostic and predictive performances. Results RBF was different in ci0 vs ci1 (147.9 +/- 46.3 vs 126.0 +/- 49.4 ml/min/100 g, p = .02) and ci2 vs ci3 (92.9 +/- 46.9 vs 70.8 +/- 37.8 ml/min/100 g, p = .03). RBF in the stable group was higher than that in the impaired group (144.73 +/- 49.33 vs 102.19 +/- 47.58 ml/min/100 g, p < .001). AUCs in distinguishing renal allograft fibrosis and predicting long-term allograft dysfunction for RBF were higher than cortical ADC(T) (ci0 vs ci1-3, 0.76 vs 0.59, p < .001; ci0-1 vs ci2-3, 0.79 vs 0.68, p = .01; ci0-2 vs ci3, 0.79 vs 0.68, p = .01; 0.76 vs 0.60, p = .04, respectively). Conclusion Compared to reduced FOV IVIM DWI, ASL was a more promising technique for noninvasively distinguishing renal allograft fibrosis degree and predicting long-term allograft dysfunction.

Automated summary

ASL was found to be more promising than IVIM DWI in distinguishing renal allograft fibrosis degree and predicting long-term allograft dysfunction.