Zhou H, et al. - Researchers investigated the links between renal R2* values (a parameter of tissue deoxyhemoglobin concentration detected by blood oxygen level-dependent (BOLD)-MRI] and clinical parameters in patients with chronic kidney disease (CKD). They also inquired about a possible association between renal R2* values and the risk for progression of CKD. They found that, with the decline of renal function, the clinical feasibility of BOLD-MRI to assess renal oxygenation and cortex hypoxia aggravated. They also identified cortex hypoxia as a prognostic marker in the progression of CKD.

Methods

• This prospective observational study was carried out in China from March 2013 to August 2014, including 60 patients with CKD.  
• Researchers obtained cortical and medullary R2* (CR2* and MR2*) values by performing a region of interest-based BOLD-MRI.
• They gathered data on demographics and clinical characteristics.
• An absolute 30% decline in the estimated glomerular filtration rates (eGFR; CKD-Epidemiology Collaboration equations) or initiation of dialysis during follow-up was the primary end point (CKD progression).

Results

• Patients with CKD vs healthy controls had significantly higher CR2* and MR2* values.
• A positive correlation of CR2* levels with 24-h urinary protein excretion, blood urea nitrogen, creatinine, and uric acid was observed, but CR2* levels showed negative association with baseline eGFR, 24-h creatinine clearance, eGFR slope, serum albumin, and the use of angiotensin II type 1 receptor blockade.
• During follow-up, CR2* levels, vs the MR2* levels and medullary cortical ratios, had the highest areas under the curve.
• In Kaplan-Meier survival analysis, best prognosis was seen in patients with CKD in the lowest tertile of the CR2* levels vs the other 2 tertiles.
• Cox proportional hazard regression models revealed that baseline eGFR and CR2* tertiles were related to the progression of CKD.
• Findings revealed only CR2* tertiles correlated negatively with the eGFR slope.