Comparison of blood oxygen level-dependent imaging and diffusion-weighted imaging in early diagnosis of acute kidney injury in animal models

Abstract

Background: Early diagnosis of acute kidney injury (AKI) has clinical importance. Current methods are neither adequately sensitive nor specific. Blood oxygen level-dependent (BOLD) imaging and diffusion-weighted imaging (DWI) may help to assess AKI in the early phase.

Purpose: To investigate the feasibility of BOLD imaging and DWI in the assessment of AKI and compare the sensitivities of both techniques in early detection of renal damage.

Study type: Prospective animal study.

Animal model: Thirty New Zealand white rabbits.

Field strength/sequence: 3 T clinical MRI/BOLD and DWI.

Assessment: Thirty rabbits were divided into three groups (severe AKI group, mild AKI group, and control group). Transarterial renal embolization with different doses of microspheres was performed to create severe and mild AKI disease models. All the MRI scans of kidneys were conducted within 2 hours after the embolization procedure. Histological examinations with hematoxylin and eosin staining were performed to validate renal damage.

Statistical tests: Analysis of variance (ANOVA) for comparisons between groups, and paired t-test for tests within the same group. P < 0.05 was considered statistically significant.

Results: Both R2* and apparent diffusion coefficient (ADC) showed significant differences between the severe AKI group (56.34 ± 3.45 s-1 for R2*, 1.14 ± 0.23 mm² /s for ADC) and the control group (28.24 ± 2.26 s-1 for R2*, 1.94 ± 0.33 mm² /s for ADC, both P < 0.01). However, the ADC values did not show significant differences (P = 0.41) between mild AKI group (1.88 ± 0.31 mm² /s for ADC) and the control group (1.94 ± 0.33 mm² /s for ADC), while R2* was still useful in differentiating the two groups (52.32 ± 4.1 s-1 vs. 28.24 ± 2.26 s-1 for R2*, P < 0.01). The histopathologic results were found to be correlated with MRI findings.

Data conclusion: BOLD contrast and DW images are both effective in detecting AKI noninvasively, but BOLD imaging is more sensitive in early detection of mild ischemia than DWI.

Level of evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:719-724.

Keywords: BOLD; acute kidney injury; diffusion-weighted imaging; rabbits.