Capability of arterial spin labeling combined with morphological characteristics to distinguish early- and mid-stage chronic kidney disease: a prospective study on 5 T MRI.

BACKGROUND: Non‑invasive imaging biomarkers are increasingly recognized for their potential to complement estimated glomerular filtration rate (eGFR) in chronic kidney disease (CKD) staging, yet the combined diagnostic value of arterial spin labeling (ASL) perfusion and morphological parameters at 5 Tesla (5 T) magnetic resonance imaging (MRI) remains unexplored. In this study, we prospectively investigated the capability of ASL combined with morphological characteristics in identifying early‑stage (G1-G2) versus mid‑stage (G3A-G3B) CKD. METHODS: A total of 103 clinically diagnosed CKD patients (66 in early-stage, 37 in mid-stage) underwent renal MRI examination on 5 T. Quantitative measurements included renal length, width, thickness, cortical thickness, cortical signal homogeneity, and cortical renal blood flow (RBF). Qualitative evaluation of corticomedullary differentiation (CMD) was also performed. Independent samples t-test, Mann-Whitney U test, and Pearson χ2 test were used to compare differences between groups. Significant imaging characteristics underwent multivariable logistic regression to identify independent diagnostic factors. The diagnostic efficacy of each characteristic and the combined RBF-morphology model was assessed using the receiver operating characteristic (ROC) curve. RESULTS: Compared with the early-stage group, the mid-stage group showed significantly lower renal length (t=2.62), width (Z=-2.61), cortical thickness (Z=-3.69), and RBF (Z=-5.07), along with greater cortical signal heterogeneity (Z=-4.55) and worse CMD contrast (χ2=25.97) (all P<0.001). Multivariate analysis identified renal length (P=0.004), CMD contrast (P=0.010), cortical signal heterogeneity (P=0.022), and RBF values (P=0.002) as independent factors for differentiating early- from mid-stage CKD. ROC analysis showed that the area under the curve (AUC) values for renal length, CMD contrast, cortical signal heterogeneity, RBF values, and the combined RBF-morphology model were 0.629 (P=0.024), 0.707 (P<0.001), 0.771 (P<0.001), 0.802 (P<0.001), and 0.916 (P<0.001), respectively. CONCLUSIONS: The combination of ASL and morphological characteristics achieves significantly better diagnostic performance between early- and mid-stage CKD than any single imaging characteristic, suggesting that 5 T MRI-derived perfusion and morphological biomarkers may serve as complementary imaging indicators for assessing renal structural and functional alterations in CKD.