Is low b-factors-based apparent diffusion coefficient helpful in assessing renal dysfunction?

Purpose: To investigate whether low b-factors-based apparent diffusion coefficient (ADC) is helpful in assessing renal dysfunction. Materials and methods: Forty-four subjects were recruited, and classified as having severe renal injury group (sRI) or not (non-sRI) according to a threshold of estimated glomerular filtration rate (eGFR) = 30 ml/min/1.73 m. A free-breathing DWI with 7 b-factors (0, 20, 40, 80, 200, 400, and 800 s/mm) was performed. After choosing an anatomical section that covered the largest part of right kidney, the regions of interest covered the renal parenchyma. For each subject, two apparent diffusion coefficients based on all b-factors less than 400 s/mm (ADC) and 800 s/mm (ADC) were calculated by fitting the signal intensity at different b-factors to a mono-exponential decay, respectively. It was found that the examination time of the free-breathing DWI sequence in this study can be reduced from 3.27 to 2.55 min if the b-factor (800 s/mm) is removed. Results: ADC was larger than ADC in each group (P < 0.05). Both ADC and ADC were smaller in the sRI group than those in the non-sRI group (P < 0.01), and they were linearly related with eGFR (P < 0.05). While a significant difference was not found between the two coefficients to differentiate sRI from non-sRI participants (P > 0.05), a strong correlation was present between ADC and ADC (r = 0.856, P < 0.001). Conclusion: The low b-factors-based ADC was an economical option for reducing the examination time without sacrificing its diagnostic performance.