Angiography-based Quantification Of Blood Flow And Its Application In Evaluation Of The Renal Sympathetic Denervation

Renal sympathetic denervation(RDN)is a novel interventional approach for treating resistant hypertension.The extent of denervation has a direct impact on the therapeutic effect.Consequently,real-time evaluation of the extent of denervation might help the clinicians decide whether the denervation is sufficient or not.Studies indicate that the renal blood flow will increase instantly after effective denervation.To address the difficulty in real-time assessment of the extent of renal sympathetic denervation,the present study proposes an angiography-based approach and system for evaluating the blood flow.Quantification of the blood flow changes before and after RDN was used as a metric to evaluate the extent of denervation.The entire evaluating system consists of image acquisition,image processing,blood flow analysis and sympathetic activity assessment modules.Image processing module,which incorporates the main algorithm,aims to obtain the grayscale information in the region of interest.Then the blood flow analysis module is applied to convert the grayscale information into quantitative blood flow.Finally,the change of blood flow before and after operation is transformed to denervation assessment index by the assessment module.The animal experiments were carried out to investigate the major factors that influenced the gray value calculation.Gray level variation was linearly correlated with the blood flow with a coefficient of 0.94 after calibration.Subsequently,the effectiveness of the proposed system was assessed in 12 patients who underwent RDN.There was a good correlation between renal blood flow change and pressure drop over 6 to 12 months,with a coefficient of 0.71.In summary,to meet the clinical need of evaluating the extent of denervation during RDN,the present study proposed an angiography-based system to quantify the blood flow changes in real-time and used it to assess the effect of renal sympathetic denervation.Preliminary results showed that the blood flow change had a good correlation with the pressure drop during follow-up.