Multifunctional Magnetic Resonance Imaging for the assessment of renal pathological alterations in IgA Nephropathy

Background : Functional magnetic resonance imaging (fMRI) is a noninvasive method to evaluate the renal volume, function, perfusion, and degree of injury. We aimed to evaluate the application of fMRI in assessing the renal histopathological injuries in patients with IgA nephropathy (IgAN). Methods: 95 patients were prospectively enrolled, fMRI including intravoxel incoherent motion (IVIM), diffusion tensor imaging (DTI), and diffusion kurtosis imaging (DKI) were performed, renal biopsy was performed within 3 days after fMRI examination. 31 patients with pathologically confirmed IgAN were selected for further analysis, glomerulosclerosis index (GSI) and tubulointerstitial fibrosis index (TBI) were assessed by two experienced pathologists. Results: Both GSI and TBI were negatively correlated with the true diffusion coefficient (D, cortex), mean diffusivity (MD, cortex and medulla), fractional anisotropy (FA, medulla), and axial diffusivity (Da, cortex and medulla), and positively correlated with the mean kurtosis (MK, cortex) and axial kurtosis (Ka, cortex and medulla). The area under the receiver operating characteristic (ROC) curves (AUCs) for the discrimination of a ≤ 25% versus >25% GSI were 0.74, 0.79, 0.88, 0.76, 0.75, and 0.80 by the D (cortex), Da (medulla), FA (medulla), MK (cortex) and Ka (cortex and medulla), respectively; And the AUCs for distinguishing a ≤ 25% versus > 25% TBI were 0.73, 0.75, 0.81, 0.79, 0.80, 0.72, 0.81, and 0.83 by the MD (cortex and medulla), Da (medulla), FA (medulla), MK (cortex and medulla), and Ka (cortex and medulla), respectively. The AUCs for differentiating a ≤ 25% and > 25% GSI and TBI were 0.900 and 0.80, 0.82 and 0.86 by DTI and DKI composite parameter, respectively. Conclusions : DTI and DKI were valuable sequences for assessment of renal moderate-to-severe histopathological alterations in patients with IgAN. Trial registration : This study was registered at the Chinese Clinical Trial registry with the registration number was ChiCTR1800020390.