USE OF MAGNETIC RESONANCE IMAGING WITH PARAMAGNETIC CONTRAST IN EVALUATION OF LOCAL RENAL DENERVATION IMPACT ON THE RENAL ARTERIES WALLS

N. I. Ryumshina; I. V. Zyubanova; A. E. Baev; V. F. Mordovin; P. I. Lukyanenok; E. A. Vusik; V. Y. Usov

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USE OF MAGNETIC RESONANCE IMAGING WITH PARAMAGNETIC CONTRAST IN EVALUATION OF LOCAL RENAL DENERVATION IMPACT ON THE RENAL ARTERIES WALLS

N. I. Ryumshina, I. V. Zyubanova, A. E. Baev, V. F. Mordovin, P. I. Lukyanenok, E. A. Vusik, V. Y. Usov

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Abstract

Aim: We evaluated the dependencies of the damage of the arterial wall on the energy of the radiofrequency pulse in renal denervation, as well as the relationships between the MRI features of the perivascular damage around the renal arteri es and the degree of the subsequent decrease of the arterial pressure. Material and methods: 34 patients (as old as 56±17 years) with resistant hypertension were included, in everybody the radiofrequency ablation (RFA) of the sympathetic nerves of renal arteries was carried out. Initially the office measured arterial pressure was as high as 140–230 / 74–162 mm Hg, whereas the average 24-h monitor of the arterial pressure gave the values as high as 137–210/57–148 mm Hg. The MRI studies were performed using MRI scanner «Titan Vantage» (by «Toshiba Medical Ltd», with the field induction 1,5 Т). After this the intravenous contrast enhancement has been carried out (with0,5 Мsolution, 0,2 ml/Kg), with repeat acquisition of Т1-weighted spin-echo images in 3–5 min after contrast injection. Absolute values of the image intensities were obtained from three regions drawn over the arterial wall of the renal artery, on the frontal slices of the aorta and renal region, in T1-weighted spin-echo images in particular — over abdominal aorta and orifice of the renal artery, over the middle part of the renal artery and over the distal branches of the renal arteries, on both sides. The index of enhancement (IE) was then calculated from these data, as ratio of intensities of contrast-enhanced image to the initial non-enhanced MRI scan. Results. Correlation between initial values of IE in proximal and middle parts of the left renal artery and diastolic arterial pressure was significant and in particular expressed as Diastolic AP=(62,26+13,171)×IEproximal (r=0,615; p=0,01) and Diastolic AP=(66,517+8,903)×IEmiddle (r=0,57; p=0,03), respectively. When comparing the IE values over the middle segment of the right renal artery to the indices of power of the ablation procedures carried out, there is a significant correlation as: IE=(0,09+0,03)×(Total energy) (r=0,475; p=0,025), verifying the significancy of direct relationship between delivered energy and periarterial damage of the renal arteries. No significant differences were revealed between proximal and distal regions of the renal arteries. The most essential and valuable fact of the study was that there is highly significant reverse correlation between IE of the arterial wall and arterial pressure in the patients studied in six months after the treatment, in particular as Diastolic AP=(108,82–13,92)×IEmiddle (r= -0,503; p=0,01224) and Diastolic AP=(108,54–13,23)×IEdistal (r=-0,484; p=0,0224) of the right renal artery respectively, and а также Diastolic AP=(94,38–5,28)×IEmiddle (r=-0,296; p=0,15994) as to left renal artery. The damage of the arterial wall was thus of significant prognostic value in regard to decrease of arterial pressure in renal artery denervation. Conclusion: Contrast-enhanced MRI study of renal arteries provides adequate diagnostic information on the anatomic condition of arterial walls and periarterial tissue and should be accepted as both first-line diagnostic techniques in patients with resistant arterial hypertension and for the follow-up of these persons after radiofrequence desympatization, employing set of quantitative methods.