The effect of hypertension on the apparent diffusion coefficient values of kidneys.

ABSTRACT

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION Despite the end-organ damage caused by hypertension, renal microvascular functions were preserved and hypertension did not affect ADC values.