Abstract: Objective: To explore the mapping and recognition ability of the intravoxel incoherent motion (IVIM) sequence for renal edema in patients with nephrotic syndrome (NS). Methodology: A retrospective study was conducted on 35 patients with NS (including minimal change nephropathy, focal segmental glomerulosclerosis, membranous nephropathy) and 25 patients with IgA nephropathy (without NS) as the control group from June 2015 to December 2024. All patients completed 24⁃hour urine protein quantification, blood biochemistry, renal function, renal B⁃ultrasound, renal biopsy pathology, and renal magnetic resonance imaging. IVIM sequence data (including standard apparent diffusion coefficient sADC, pure water diffusion coefficient D, pseudo⁃diffusion coefficient D*, perfusion fraction f) were collected. Differences in clinical, pathological, and imaging indexes were analyzed. Results: There was no difference in renal function between the two groups. Compared with the control group, the left renal length and degree of renal edema increased in the NS group (P<0.001). The sADC values of renal cortex and medulla in the NS group were significantly higher (P=0.013, P=0.018), and the D* values were significantly lower (P=0.021, P=0.011) than those in the control group. There was no significant difference in D and f values. Conclusion: The IVIM sADC value of renal tissue in NS patients was significantly increased, and the D* value was significantly decreased, showing promise for characterizing the degree of renal parenchymal edema in NS patients.

Key words: nephrotic syndrome, intravoxel incoherent motion, renal interstitial edema