Diffusion-weighted imaging for staging chronic kidney disease: a meta-analysis

Objective: To evaluate stages of chronic kidney disease (CKD) by apparent diffusion coefficient (ADC) obtained from diffusion weighted imaging (DWI) using a meta-analysis. Methods: Literature databases were searched from PubMed, Web of Science, Cochrane and Embase to identify relevant articles about DWI in CKD between 1999 and 2017. ADC values were extracted from the healthy group and CKD patients with different stages. Meta-analysis was conducted using STATA v. 12.0. A random-effects model was performed to acquire the effect estimate, which was expressed as a pooled weighted mean difference (WMD) with 95% confidence interval (CI). We performed comparisons of ADC values between the following groups: (1) the ADC values of the normal kidneys vs earlier Stage 1-2 of CKD; (2) Stage 3 vs the Stage 1-2 of CKD; (3) the Stage 4-5 vs the Stage 3. Results: Six studies were included in this meta-analysis. The CKD patients with earlier Stage 1-2 showed lower ADC values than the healthy subjects [WMD = -0.09, 95% CI(-0.12 to -0.06), p < 0.001]. However, no obvious difference in ADC values was found between the Stage 3 and Stage1-2 of CKD [WMD = -0.09, 95% CI (-0.18 to 0.01), p = 0.08]. The CKD Stage3 had higher ADC values than those of Stage4-5 [WMD = -0.21, 95% CI (-0.32 to -0.11), p = 0.01]. Conclusion: DWI is an accurate and non-invasive imaging technique for early diagnosis and staging of CKD. Quantitative DWI may potentially play a role in making clinical decisions in the follow-up of CKD. Advances in knowledge DWI can be a valuable tool for staging of CKD.