Table 7.
The correlation between mGFR and UACR and MRI biomarkers of kidney haemodynamics, micro- and macrostructure and oxygenation
| mGFR | UACR | UACR (bivariate analysis with mGFR + imaging variable) | ||||
|---|---|---|---|---|---|---|
| Variable | Pearson correlation (r) | P-value | Spearman correlation (r) | P-value | Pearson correlation (r2) | P-value |
| mGFR | –0.81 | <.0001 | 0.15 | .02 | ||
| Kidney haemodynamics | ||||||
| MAF (mL/min/1.73 m2) | 0.92 | <.0001 | –0.78 | <.0001 | 0.16 | .63 |
| PSV (cm/s) | 0.32 | .02 | –0.28 | .03 | 0.15 | .95 |
| EDV (cm/s) | 0.79 | <.0001 | –0.75 | <.0001 | 0.23 | .07 |
| RARI | –0.76 | <.0001 | 0.70 | <.0001 | 0.21 | .13 |
| ASL perfusion cortex (mL/min/100 g) | 0.70 | <.0001 | –0.65 | <.0001 | 0.15 | .51 |
| Global perfusion (mL/min/100 g) | 0.75 | <.0001 | –0.63 | <.0001 | 0.16 | .59 |
| Kidney macrostructure | ||||||
| Kidney volume (mL/1.73 m2) | 0.61 | <.0001 | –0.50 | <.0001 | 0.16 | .49 |
| Kidney oxygenation | ||||||
| BOLD R2* cortex (per s) | 0.07 | .59 | –0.11 | .41 | 0.14 | .82 |
| BOLD R2* medulla (per s) | 0.35 | .008 | –0.34 | .01 | 0.23 | .06 |
| Kidney microstucture | ||||||
| ADC cortex (10–3 mm2/s) | 0.48 | .0002 | –0.37 | .005 | 0.21 | .36 |
| ADC medulla (10–3 mm2/s) | 0.28 | .03 | –0.27 | .05 | 0.23 | .20 |
| R1 cortex (per s) | 0.78 | <.0001 | –0.82 | <.0001 | 0.36 | .003 |
| R1 medulla (per s) | 0.20 | .13 | –0.33 | .01 | 0.25 | .04 |
| IVIM D cortex (10−3 mm2/s) | 0.44 | .0007 | –0.27 | .04 | 0.30 | .03 |
| IVIM D medulla (10−3 mm2/s) | 0.35 | .007 | –0.23 | .08 | 0.24 | .15 |
| IVIM D* cortex (10−3 mm2/s) | –0.09 | .54 | –0.12 | .38 | 0.19 | .47 |
| IVIM D* medulla (10−3 mm2/s) | –0.00 | 1.00 | –0.18 | .19 | 0.15 | .44 |
| IVIM f cortex (%) | –0.17 | .23 | 0.09 | .54 | 0.37 | .005 |
| IVIM f medulla (%) | –0.21 | .13 | 0.17 | .22 | 0.19 | .17 |
| MTR cortex (%) | 0.23 | .09 | –0.26 | .05 | 0.15 | .74 |
| MTR medulla (%) | 0.13 | .34 | –0.14 | .30 | 0.15 | .82 |
A univariate linear regression was used to evaluate the linear association of each MRI biomarker with mGFR and UACR (mGFR or UACR as a dependent variable, MRI biomarker as an independent variable). Bivariate predictors of UACR were examined using mGFR as one variable and adding one MRI endpoint using linear regression only in the DKD subjects.