ABSTRACT

The purpose of this study was to diagnose hypertension- induced renal microvascular dysfunction using renal diffusion magnetic resonance imaging (MRI) and to identify any correlation between blood pressure level and apparent diffusion coefficient (ADC) values.

The study included 77 consecutive patients (41 women and 36 men). The patients were divided into 4 groups according to their blood pressure level. Group 1 consisted of normotensive control patients; group 2, pre-hypertensive patients; group 3, stage 1 hypertensive patients; and group 4, stage 2 hypertensive patients. All patients underwent transverse diffusion-weighted multi-section echo-planar MRI. In the transverse ADC maps, rectangular regions of interest were placed in the cortex at 3 sites (upper, middle, and lower pole) of each kidney. The ADCs of the kidneys were calculated separately for low, average, and high b values to enable the differentiation of the relative influence of the perfusion fraction and true diffusion. In addition, a multi-slab balanced turbo field-echo magnetic resonance angiographic technique (without the use of a contrast agent) was used to exclude renal artery stenosis.

There was no statistically significant difference between the groups in age, and no significant correlation between the ADC values of both kidneys and blood pressure level in each group (P > 0.05). In addition, the ADC values of patients with microalbuminuria did not differ from those of the other patients (P > 0.05).

Despite the end-organ damage caused by hypertension, renal microvascular functions were preserved and hypertension did not affect ADC values.

Keywords: hypertension • diffusion-weighted MRI • end-organ damage • kidney