Table 5.
Descriptive statistics and predictive properties (ROC AUC) of univariate imaging markers to distinguish between stage G3 and stages G4/G5 in subjects with DKD, including respective specificity and sensitivity for Youden cut-off values
| Stage G3 | Stages G4/G5 | Prediction performance | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Variable | n | Mean (SD) | n | Mean (SD) | ROC AUC | Cut-off | Sensitivity | Specificity | *P-value |
| Kidney haemodynamics | |||||||||
| MAF (mL/min/1.73 m2) | 16 | 653 (133) | 20 | 447 (118) | 0.88 | <605 | 1.00 | 0.69 | .004 |
| PSV (cm/s) | 16 | 59.8 (14.2) | 20 | 43.1 (11.1) | 0.83 | <53.2 | 0.90 | 0.69 | .005 |
| EDV (cm/s) | 16 | 11.3 (3.2) | 20 | 6.72 (2.5) | 0.87 | <8.35 | 0.90 | 0.81 | .002 |
| RARI | 16 | 0.81 (0.06) | 20 | 0.84 (0.06) | 0.68 | >0.84 | 0.60 | 0.81 | .11 |
| ASL perfusion cortex (mL/min/100 g) | 16 | 96.4 (39.7) | 19 | 68.2 (37.8) | 0.72 | <79 | 0.79 | 0.69 | .05 |
| Global perfusion (mL/min/100 g) | 16 | 352 (43) | 20 | 278 (93) | 0.76 | <305 | 0.75 | 0.81 | .01 |
| Kidney macrostructure | |||||||||
| Kidney volume (mL/1.73 m2) | 16 | 185 (27.8) | 20 | 169 (43.4) | 0.63 | <155 | 0.40 | 0.94 | .20 |
| Kidney oxygenation | |||||||||
| BOLD R2* cortex (per s) | 15 | 17.2 (1.6) | 18 | 17 (1.25) | 0.51 | <16.1 | 0.28 | 0.87 | .56 |
| BOLD R2* medulla (per s) | 15 | 24.5 (3.7) | 18 | 22.8 (3.6) | 0.64 | <23.5 | 0.72 | 0.60 | .19 |
| Kidney microstructure | |||||||||
| ADC cortex (10–3 mm2/s) | 15 | 2.37 (0.17) | 19 | 2.27 (0.22) | 0.67 | <2.32 | 0.68 | 0.73 | .18 |
| ADC medulla (10–3 mm2/s) | 15 | 2.21 (0.24) | 19 | 2.17 (0.24) | 0.59 | <2.21 | 0.74 | 0.60 | .58 |
| R1 cortex (per s) | 16 | 0.65 (0.03) | 20 | 0.62 (0.04) | 0.76 | <0.62 | 0.50 | 0.94 | .02 |
| R1 medulla (per s) | 16 | 0.55 (0.02) | 20 | 0.54 (0.02) | 0.70 | <0.55 | 0.80 | 0.63 | .06 |
| IVIM D cortex (10−3 mm2/s) | 15 | 1.96 (0.17) | 19 | 1.87 (0.32) | 0.62 | <1.91 | 0.63 | 0.73 | .30 |
| IVIM D medulla (10−3 mm2/s) | 15 | 1.86 (0.17) | 19 | 1.85 (0.23) | 0.51 | <1.72 | 0.37 | 0.80 | .87 |
| IVIM D* cortex (10−3 mm2/s) | 15 | 48.2 (48.5) | 17 | 143 (482) | 0.42 | >2010 | 0.06 | 1.00 | .52 |
| IVIM D* medulla (10−3 mm2/s) | 14 | 48.7 (58.6) | 17 | 306 (1035) | 0.53 | >19.5 | 0.76 | 0.50 | .69 |
| IVIM f cortex (%) | 15 | 14.7 (5.13) | 17 | 15.6 (6.3) | 0.51 | >12.3 | 0.82 | 0.33 | .66 |
| IVIM f medulla (%) | 14 | 14.6 (5.59) | 17 | 14.3 (5.9) | 0.52 | <12 | 0.47 | 0.71 | .89 |
| MTR cortex (%) | 16 | 21.6 (2.41) | 20 | 22 (2.0) | 0.54 | >20.7 | 0.75 | 0.38 | .57 |
| MTR medulla (%) | 16 | 23.6 (2.35) | 20 | 23.9 (2.6) | 0.52 | >22.2 | 0.70 | 0.44 | .75 |
| Biochemistry | |||||||||
| eGFR (mL/min/1.73 m2) | 16 | 46.3 (12.1) | 20 | 25.9 (6.3) | 0.96 | <31 | 0.85 | 0.94 | .008 |
| UACR (mg/mmol) | 16 | 33 (47) | 20 | 94.2 (97) | 0.72 | >97 | 0.45 | 0.94 | .05 |
GFR stages were stratified by mGFR.
*P-value of OR = 1 for the variable (Wald test) in the model. Note that P-values are inappropriate in cases when there is complete (or quasi-complete) separation of data points, i.e. when sensitivity and specificity = 1 (or close to 1).