Table 4.

Additional results of renal multiparametric MRI

	AKI	n	NO AKI	n	Healthy volunteers	n
Perfusion
Global perfusion (ml/100 g/min)	168 [142–216]	10	202 [174–235]	9	220 [174–242]	12
Regional perfusion ratio (cortex/medulla)	2.4 [2.2–3.3]	10	2.2 [1.7–3.4]	7
Resistance index*	0.90 [0.82–0.93]	10	0.79 [0.75–0.86]	8
Structure and regional water diffusion
Total kidney volume (ml)	356 [331–437]	10	390 [359–447]	9	403 [345–430]	12
T1 cortex (ms)†	1560 [1524–1638]	8	1522 [1497–1638]	8	1459 [1400–1525]	12
T1 medulla (ms)	1838 [1732–1872]	8	1792 [1695–1870]	8	1732 [1661–1850]	12
T2 cortex (ms)	120 [113–134]	8	124 [119–141]	8
DWI cortex ADC (× 10–3 mm2/s)	1.9 [1.9–2.1]	8	2.1 [1.9–2.1]	8
DWI medulla ADC (× 10–3 mm2/s)	1.9 [1.9–2.0]	8	2.1 [1.8–2.1]	8
DWI cortex D (× 10–3 mm2/s)	1.8 [1.7–1.9]	8	1.9 [1.7–2]	8
DWI cortex D* (× 10–3 mm2/s)	26 [23–29]	8	27 [24–28]	8
DWI cortex fp	0.13 [0.11–0.15]	8	0.13 [0.11–0.14]	8
DWI medulla D (× 10–3 mm2/s)	1.8 [1.7–1.9]	8	1.9 [1.7–2]	8
DWI medulla D* (× 10–3 mm2/s)	26 [23–17]	8	27 [26–28]	8
DWI medulla FP	0.14 [0.11–0.17]	8	0.15 [0.12–0.16]	8

Results of renal multiparametric MRI in 19 patients treated in ICU for respiratory failure due to COVID-19 with AKI or NO AKI, and 12 healthy volunteers of similar age. Data presented as median [quartile range]. Significant differences from Mann–Whitney U test between AKI and NO AKI groups are indicated by * if p < 0.05. Significant differences from one way Kruskal–Wallis ANOVA between all groups are indicated by † if p < 0.05 and ††† if p < 0.001. Valid numbers of MRI examinations are specified for each measure and group. Additional results are presented in Fig. 1

T₁ longitudinal relaxation time, T₂ transverse relaxation time, DWI diffusion weighted imaging, ADC apparent diffusion coefficient, D pure diffusion, D* pseudodiffusion, f_p perfusion fraction