Imaging the pH evolution of an acute kidney injury model by means of iopamidol, a MRI-CEST pH-responsive contrast agent

Purpose: To investigate in vivo possible pH level alterations following an acute renal failure disease using a MRI-CEST pH responsive contrast agent. The impact of functional evolution in different renal compartments over time was also investigated.

Methods: a mouse model of acute kidney injury was obtained by glycerol-induced rhabdomyolysis. pH maps were obtained using Iopamidol (0.75 g iodine/kg b.w. corresponding to 2.0 mmol/kg) in a control group (n = 3) and in the acute kidney injury group (n = 6) at 1, 3, 7, 14, and 21 days after the damage induction at 7T. Histology assessment of renal damage and blood urea nitrogen levels were compared with pH maps.

Results: during the acute kidney injury, there was a robust increase of pH values, which peaked after 3 days, compared with the predamage situation. In addition, it was possible to detect changes in contrast detection between the different functional regions of the damaged kidneys. Moreover, a slow restoration of normal pH values was observed three weeks after the glycerol injection.

Conclusions: pH appears to be a good parameter to assess the early detection of kidney injury as well as it acts as a reporter of the recovery toward the physiologic functionality.