[Evaluation of kidney oxygen bioavailability in acute renal failure by blood oxygen level dependent magnetic resonance imaging].

OBJECTIVE

To assess the kidney oxygen bioavailability in acute renal failure using blood oxygen level dependent (BOLD) magnetic resonance (MR) imaging.

METHODS

Twenty-one patients with acute renal failure, including 18 patients with oliguric renal failure, 1 nonoliguric acute renal failure and 2 functional renal failure were enrolled in the study; 20 healthy subjects served as controls. All subjects received renal functional MR examination. BOLD MR imaging with 16 gradient-recalled-echoes on a 1.5-T scanner were performed. R2()(1/sec) values of the cortex and medulla and R2() ratio of the medulla to cortex (R2(*) ratio of M/C) of the renal were recorded respectively.

RESULTS

The R2() values of the medulla was higher than those of the cortex in controls (17.64 +/-1.86/sec vs 13.73 +/-0.49/sec, P<0.00). The R2() ratio of M/C in controls was 1.28 +/-0.06. The R2() values of the medulla (13.31 +/-4.28/sec) and cortex (12.25 +/-2.41/sec) and the R2( ) ratio of M/C (1.01 +/-0.25) in oliguric renal failure were lower than those in controls (P <0.05). Patients with functional renal failure and nonoliguric acute renal failure had higher R2() values in cortex and medulla and higher R2() ratio of M/C than those of controls.

CONCLUSION

BOLD MRI demonstrates that decreased R2() values of cortex and medulla suggest lower oxygen bioavailability in acute renal failure and decreased R2()ratio of M/C suggests the disappearance of a steep cortico-medullary gradient of oxygen.