Perfusion and T2 Relaxation Time as Predictors of Severity and Outcome in Sepsis-Associated Acute Kidney Injury: A Preclinical MRI Study

J Magn Reson Imaging. 2023 Apr 7. doi: 10.1002/jmri.28698. Online ahead of print.

ABSTRACT

BACKGROUND: Preventing sepsis-associated acute kidney injury (S-AKI) can be challenging because it develops rapidly and is often asymptomatic. Probability assessment of disease progression for therapeutic follow-up and outcome are important to intervene and prevent further damage.

PURPOSE: To establish a noninvasive multiparametric MRI (mpMRI) tool, including T₁ , T₂ , and perfusion mapping, for probability assessment of the outcome of S-AKI.

STUDY TYPE: Preclinical randomized prospective study.

ANIMAL MODEL: One hundred and forty adult female SD rats (65 control and 75 sepsis).

FIELD STRENGTH/SEQUENCE: 9.4T; T₁ and perfusion map (FAIR-EPI) and T₂ map (multiecho RARE).

ASSESSMENT: Experiment 1: To identify renal injury in relation to sepsis severity, serum creatinine levels were determined (31 control and 35 sepsis). Experiment 2: Animals underwent mpMRI (T₁ , T₂ , perfusion) 18 hours postsepsis. A subgroup of animals was immediately sacrificed for histology examination (nine control and seven sepsis). Result of mpMRI in follow-up subgroup (25 control and 33 sepsis) was used to predict survival outcomes at 96 hours.

STATISTICAL TESTS: Mann-Whitney U test, Spearman/Pearson correlation (r), P < 0.05 was considered statistically significant.

RESULTS: Severely ill septic animals exhibited significantly increased serum creatinine levels compared to controls (70 ± 30 vs. 34 ± 9 μmol/L, P < 0.0001). Cortical perfusion (480 ± 80 vs. 330 ± 140 mL/100 g tissue/min, P < 0.005), and cortical and medullary T₂ relaxation time constants were significantly reduced compared to controls (41 ± 4 vs. 37 ± 5 msec in cortex, P < 0.05, 52 ± 7 vs. 45 ± 6 msec in medulla, P < 0.05). The combination of cortical T₂ relaxation time constants and perfusion results at 18 hours could predict survival outcomes at 96 hours with high sensitivity (80%) and specificity (73%) (area under curve of ROC = 0.8, J_max = 0.52).

DATA CONCLUSION: This preclinical study suggests combined T₂ relaxation time and perfusion mapping as first line diagnostic tool for treatment planning.

LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.

PMID:37026419 | DOI:10.1002/jmri.28698