ASL, DTI, and T1 mapping in identifying immune and non-immune pathogenic factors of chronic allograft injury.

BACKGROUND: Chronic allograft injury (CAI) has a complex etiology and various clinical and pathological manifestations, posing challenges for clinical diagnosis and treatment. This study aimed to explore the value of arterial spin labeling (ASL), diffusion tensor imaging (DTI), and T1 mapping in identifying the causes of CAI. METHODS: This study included 69 kidney transplant recipients. Based on the estimated glomerular filtration rate (eGFR) and biopsy results, the recipients were classified into three groups: Group A, recipients with good renal allograft function (eGFR ≥60 mL/min/1.73 m2); Group B, recipients with immune-mediated factors; and Group C, recipients with non-immune-mediated factors. ASL, DTI, and T1 mapping were performed in all patients, and magnetic resonance imaging (MRI) parameters were calculated and analyzed. RESULTS: Renal blood flow (RBF) was higher in the recipients with normal renal allograft function than in those with CAI. Cortical and medullary apparent diffusion coefficient (ADC) values were lower in the immune factors group (2.05±0.22/2.06±0.22 ×10-3 mm2/s) than in the non-immune factors group (2.24±0.23/2.25±0.24 ×10-3 mm2/s). Conversely, cortical T1 values were higher in in the immune-mediated group than in the non-immune-mediated group. The area under the curve (AUC) value for cortical ADC, medullary ADC, and cortical T1 values in identifying CAI pathogenic factors was 0.716, 0.687, and 0.806, respectively. The combination of DTI and T1 mapping achieved better diagnostic efficiency for distinguishing between patients in Group B and Group C than DTI or T1 mapping alone [AUC =0.825, 95% confidence interval (CI): 0.699-0.952, P<0.001]. CONCLUSIONS: ASL, DTI, and T1 mapping can distinguish between recipients with normal renal allograft function and those with CAI. Further, DTI and T1 mapping can differentiate between immune and non-immune pathogenic factors of CAI.