Hemosiderin deposition on the renal cortex by mechanical hemolysis due to malfunctioning prosthetic cardiac valve: report of MR findings in two cases.

We present two cases of mechanical hemolysis due to malfunctioning prosthetic cardiac valves in which MRI was characteristic. The signal intensity of the renal cortex was much lower than that of the medulla on T2-weighted images due to deposition of hemosiderin in proximal convoluted tubules by intravascular hemolysis. These MR findings are identical to those in paroxysmal nocturnal hemoglobinuria.