Non-contrast angiography of renal artery in 3T magnetic resonance in patients with refractory arterial hypertension before renal denervation

Abstract

Introduction: Catheter-based renal sympathic denervation is a technique for treatment of resistant arterial hypertension. Planning this procedure magnetic resonance (MR) is a non-invasive method without any radiation to reliably image the anatomical conditions like diameters, possible stenosis or abnormalities of renal arteries. Impaired renal function (GFR<30 ml/min) is a known contraindication for gadolinium based contrast agent due to the risk of nephrogenic systemic fibrosis. To address the question if imaging of the anatomy of renal arteries in 3T MR may be feasible and reliable without using contrast agent the present prospective study was performed. Methods: 34 Patients with resistant hypertension (taking four antihypertensive drugs including diuretics and long term blood pressure measurement larger than 135/85mmHg) for whom renal denervation was planned were included prospectively. In 3T magnetic resonance 3D conventional contrast MR angiography (CMRA) was performed after antecubital injection of gadopentetat-dimeglumin during breath-hold. Additionally, an inflow inversion recovery steady state free precession sequence (Inhance) was used for non-contrast MR angiography (NCMRA). Diameters of renal artery were assessed 20 mm from aortic ostium. Furthermore, the aortic diameter was measured at height of renal artery orifice. Results: 34 patients (66±8 years) were included in both conventional contrast and non-contrast MR angiography and presented a total of 76 main and accessory renal arteries. In CMRA mean renal artery diameter was 6.2±1.8 mm, in NCMRA mean renal artery was determined with 6.0±2.0 mm. Mean aortic diameters were identified with 20.4±3.2 in CMRA and with 20.1±2.8 in NCMRA. Measurements of renal artery by NCMRA closely correlate to renal artery diameters assigned by CMRA (r=0.97). Furthermore, detection of aortic diameters showed also good correlation between both MRA (r=0.92). Bland-Altman-analysis did not present any signs of under- and overestimation of both measurement methods. Conclusion: At 3T CMR determination of renal artery and aortic diameter at the orifice of the renal arteries is possible by non-contrast MR angiography as well as by 3D contrast MR angiography. Both methods provide reliable estimates of the diameter of the vessel without relevant under- or overestimation. Non-contrast MR angiography should be regarded as a powerful completely non-invasive tool to image renal arteries without the need to use potentially nephrotoxic contrast media.