T2-Weighted Imaging and Intravoxel Incoherent Motion for Monitoring Glomerulonephritis.

Abstract

BACKGROUND: Lack of reliable noninvasive diagnostic tools limits timely management of glomerulonephritis (GN), a major cause of chronic kidney disease. PURPOSE: To validate the performance of intravoxel incoherent motion (IVIM) imaging and T2-weighted imaging (T2WI) in monitoring renal injury in rats with GN. STUDY TYPE: Prospective, animal model. SUBJECTS: Eighty-one Sprague-Dawley rats (54 GN, 27 control) underwent renal MRI at nine time points from Day 2 to Week 16 (GN: n = 6; control: n = 3 per time point). FIELD STRENGTH/SEQUENCE: 3.0T; IVIM and T2WI. ASSESSMENT: IVIM parameters (D, D*, f) and standardized signal intensities (SSI) on T2WI were calculated for renal cortex and outer medulla and correlated with histology. STATISTICAL TESTS: One-way analysis of variance was used for longitudinal changes and independent t-test for comparing GN and controls at each time point. Receiver operating characteristic (ROC) curve analysis assessed diagnostic performance for identifying GN. RESULTS: Cortex, outer stripe of outer medulla (OM) and inner stripe of the outer medulla (IM) showed early SSI increase followed by gradual decline. SSI of OM was significantly higher than controls at Days 5 (2.19 ± 0.76), 10 (2.99 ± 0.34), 15 (2.46 ± 0.37), and Week 4 (2.23 ± 0.66). In GN rats, D progressively declined from Day 2 to Week 16: from 1.51 ± 0.40 to 0.91 ± 0.45 (×10 mm/s) in cortex, and from 1.37 ± 0.23 to 0.62 ± 0.19 (×10 mm/s) in outer medulla. D* and f also decreased progressively in cortex and outer medulla. Significant inverse relationships were observed between IVIM parameters and serum biomarkers (r = -0.39 to -0.80). For diagnostic performance to identify GN, D achieved the highest area under the ROC curves in the cortex (0.926, 95% CI: 0.883-0.970) and outer medulla (0.975, 95% CI: 0.953-0.997). DATA CONCLUSION: T2WI reveals early signal changes in GN. IVIM parameters track disease progression, correlate with serum biomarkers, and distinguish GN from healthy controls. TECHNICAL EFFICACY: Stage 1.