Native T1 mapping for non-invasive quantitative evaluation of renal function and renal fibrosis in patients with chronic kidney disease.

ABSTRACT

Background: To investigate the role of native T1 mapping in the non-invasive quantitative assessment of renal function and renal fibrosis (RF) in chronic kidney disease (CKD) patients. Methods: A prospective analysis of 71 consecutive patients [no RF (0%) 9 cases; mild RF (<25%) 36 cases; moderate RF (25-50%) 17 cases; severe RF (>50%) 9 cases] who were clinically diagnosed with CKD that was pathologically confirmed and who underwent magnetic resonance imaging (MRI) examination between October 2021 and September 2022 was performed. T1-C (mean cortical T1 value), T1-M (mean medullary T1 value), ΔT1 (mean corticomedullary difference) and T1% (mean corticomedullary ratio) values were compared. Correlations between T1 parameters and clinical and histopathological values were analyzed. Regression analysis was performed to determine independent predictors of RF. The areas under the receiver operating characteristic curve (AUC) were calculated to assess the diagnostic value of RF. Results: The T1-C, ΔT1 and T1% values (P<0.05) were significantly different in the CKD group, but T1-M was not (P>0.05). The ΔT1 and T1% values showed significant differences in pairwise comparisons among CKD subgroups (P<0.05) except for CKD 2 and 3. ΔT1 and T1% were moderately correlated with the estimated glomerular filtration rate (ΔT1 rs=-0.561; T1% r=-0.602), serum creatinine (ΔT1 rs=0.591; T1% rs=0.563), blood urea nitrogen (ΔT1 rs=0.433; T1% rs=0.435) and histopathological score (ΔT1 rs=0.630; T1% rs=0.658). ΔT1 and T1%, but not T1-C, were independent predictors of RF (P<0.05). ΔT1 and T1% were set as -410.07 ms and 0.8222 with great specificity [ΔT1 91.7% (77.5-98.2%); T1% 97.2% (85.5-99.9%)] to identify mild RF and moderate-severe RF. The optimal cutoff values for differentiating severe RF from mild-moderate RF were -343.81 ms (ΔT1) and 0.8359 (T1%) with high sensitivity [both 100% (66.4-100%)] and specificity [ΔT1 90.6% (79.3-96.9%); T1% 94.3% (84.3-98.8%)]. Conclusions: ΔT1 and T1% overwhelm T1-C for assessment of renal function and RF in CKD patients. ΔT1 and T1% identify patients with <25% and >50% fibrosis, which can guide clinical decision-making and help to avoid biopsy-related bleeding.