Apparent diffusion coefficient of kidneys with non-contrast magnetic resonance angiography for functional and anatomical assessment in renal artery stenosis

Table 1 Demographic characteristics and associated comorbidities of the study population

	RAS (n = 58)		Hypertensive group with normal renal arteries (n = 28)	Healthy control volunteers (n = 20)	Total (n = 106)
Age (years)	40.9 ± 14.1		36.5 ± 13.1	28.2 ± 3.9
Sex	Male	37	23	20	80
	Female	21	5	0	26
Hypertension	58		28	0	86
Diabetes mellitus	10		5	0	15
Takayasu arteritis	6		2	0	8
Chronic kidney disease	5		4	0	9
Raised serum creatinine	39		11	0	50
Mean serum creatinine (mg/dL)	2.2		1.3	0.8	1.65
Mean BUN (mg/dL)	22.8		20.5	10.6	17.97
Mean eGFR (mL/min/1.73m2)	55		89.05	131	91.68

RAS: Renal artery stenosis; BUN: Blood urea nitrogen; eGFR: Estimated glomerular filtration rate.

Table 2 Comparison of age and ADCavg values of kidneys in hypertensive patients with and without renal artery stenosis and healthy control volunteers

	RAS, n = 81	Hypertension with normal renal arteries, n = 91	P value (Comparison of patients with and without RAS)	Healthy control volunteers, n = 40
Age	40.9 ± 14.1	36.5 ± 13.1	0.035	28.2 ± 3.9
ADCaverage cortex (× 10-3 mm2/s)	1.77 ± 0.3	1.89 ± 0.2	0.002	1.90 ± 0.1
ADCaverage medulla (× 10-3 mm2/s)	1.76 ± 0.3	1.85 ± 0.2	0.021	1.84 ± 0.1
Stenosis degree	64.1 ± 17.56	-		-

RAS: Renal artery stenosis; ADC: Apparent diffusion coefficient.

Table 3 Correlations between age, stenosis degree, and apparent diffusion coefficient values of kidneys with renal artery stenosis

		Degree of stenosis	ADCavg cortex
Age	Correlation coefficient	-0.57	-0.123
	Significance (2-tailed)	0.611	0.075
Degree of stenosis	Correlation coefficient	-	-0.238
	Significance (2-tailed)	-	0.033

ADC: Apparent diffusion coefficient.

Table 4 Comparison of mean apparent diffusion coefficient values with previous studies at b 1000 within the renal artery stenosis affected kidneys and essential hypertension group

Ref.	Groups	Cortex mean ADC	Medulla mean ADC
Yildrim et al[11], 2007	RAS affected kidneys	1.8 ± 0.2
	Contralateral and EH kidneys	2.0 ± 0.1
Our study	RAS affected kidneys	1.77 ± 0.3	1.76 ± 0.3
	Contralateral kidneys	1.95 ± 0.2	1.93 ± 0.2
	EH kidneys	1.89 ± 0.3	1.85 ± 0.2
	Normal kidneys	1.90 ± 0.1	1.84 ± 0.1

RAS: Renal artery stenosis; ADC: Apparent diffusion coefficient; EH: Essential Hypertension.

Table 5 Comparison of mean apparent diffusion coefficient values at low b values (< 1000) in selected studies

Ref.	Groups	Cortex mean ADC	Medulla mean ADC
Li et al[18], 2019	Normal kidneys	2.2 ± 0.1	2.0 ± 0.1
Namimoto et al[20], 1999	RAS affected kidneys	1.55 ± 0.39	2.24 ± 0.64
	Normal kidneys	2.55 ± 0.62	2.84 ± 0.72

RAS: Renal artery stenosis; ADC: Apparent diffusion coefficient.