The Role Of Non-Contrast-Enhanced MR Angiography (NCE-MRA) Combined With Captopril Renal Scintigraphy In The Diagnosis Of Renal Vascular Hypertension

Background and objectiveSecondary hypertension accounts for about 5% to 10% of hypertension.Etiological treatment of secondary hypertension will significantly reduce the mortality and disability rate of hypertension and its complications.Therefore,it is very important to judge whether hypertension is primary or secondary and subsequent causes.Renal vascular hypertension(RVH)refers to renal artery or its main branch stenosis or occlusion caused by various causes,resulting in secondary hypertension caused by renal blood flow reduction or ischemia.Common causes of RVH include takayasu arteritis,renal atherosclerosis,systemic necrotizing vasculitis,and fibromuscular dysplasia.Atherosclerotic renal artery stenosis is the leading cause of RVH in adults.RVH has a cure,so early diagnosis,judgment of the extent of renal artery stenosis(RAS)and renal function,early and accurate treatment,to some extent,can reverse and prevent disease progression.Non-contrast-enhanced MR Angiography(NCE-MRA)is an anatomical diagnosis of RAS.It does not require contrast agents and has reproducibility.It is currently the preferred choice for the diagnosis of vascular diseases.Digital subtraction angiography(DSA)is the gold standard for diagnosing RAS,but it is an invasive examination,and there is a risk of contrast nephropathy.It can only provide anatomical stenosis and can not provide functional stenosis.Consider the above factors.DSA cannot be used as a primary screening test for patients diagnosed with RAS.There is a need for a non-invasive primary screening technique,especially for imaging techniques that can assess whether RAS is functional.Captopril renal scintigraphy(CRS)is a functional test for the diagnosis of RVH.Renal artery stenosis leads to a decrease in renal artery perfusion,which activates the renin-angiotensin-aldosterone system(RAAS system),which causes sodium retention to increase blood pressure.In addition,angiotensin II is contracted efferent arterioles,and filtration pressure is increased to maintain the glomerular filtration rate(GFR)level,so that the conventional renal dynamic imaging has a low detection rate of renal artery stenosis,and even presents a false negative.The introduction of captopril during renal dynamic imaging inhibits the conversion of angiotensin I to angiotensin II.The compensatory mechanism of angiotensin II contracting efferent arteriolesis is inhibited.renal blood flow of renal artery stenosis and the GFR is reduced,which improves detection sensitivity and diagnostic accuracy.Previous studies have reported that CRS diagnosis of RVH has a high sensitivity of 87% to 96% and specificity of 85% to 95%,but some studies have concluded that the sensitivity and specificity of its diagnosis of RVH is not ideal.This study was to investigate the diagnostic value of NCE-MRA,CRS for the RVH,and further to evaluate the value of NCE-MRA combined with CRS in the diagnosis of RVH.Methods1.We recruit number of 72 patients of highly suspected with RVH in Department of Hypertension,Henan Provincial People's Hospital(People's Hospital of Zhengzhou University)from January 2018 to October 2018,43 males and 29 females,with an average age of(54.54�16.30)years,The systolic blood pressure was(159.2 � 16.4)mmHg,and the diastolic blood pressure was(100.6 � 14.2)mmHg.Exclusion criteria: excluding MRI contraindications,excluding other causes of secondary hypertension(renal parenchymal hypertension,primary aldosteronism,pheochromocytoma,aortic coarctation,and obstructive sleep apnea hypopnea syndrome).2.All patients underwent NCE-MRA examination first,we screened 52 patients with renal artery stenosis >50%,52 patients underwent basic renal dynamic imaging and CRS,and finally a DSA examination was performed.All patients signed informed consent before each examination.the images of NCE-MRA,ECT and DSA were respectively double-blind reviewed by 2 experienced radiologists,nuclear medicine physicians,and interventional physicians.RVH diagnostic criteria: DSA renal artery trunk and / or its branch diameter stenosis 370%,considered to have hemodynamic significance.Positive criteria for CRS:(1).CRS shows peak delay and peak time is 3 6 min;(2).The relative uptake ratio of CRS compared with the relative uptake ratio of basic renal dynamic imaging is declined 3 5%;(3).CRS showed no significant changes in renal function,but basic renal dynamic imaging showed severe damage to one side of the kidney function(relative kidney intake ratio of(27)30%,peak time ? 2 min,kidney volume reduction);(4).The glomerular filtration rate of CRS is declined 3 10% than the glomerular filtration rate of basic renal dynamic imaging.Any one of the above conditions can be diagnosed as CRS positive,considering that this patient may be RVH.3.SPSS 17.0 software was used for Statistical analysis.Spearman rank correlation analysis was used to analyze the consistency of NCE-MRA and DSA in the diagnosis of renal artery stenosis.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of NCE-MRA in the diagnosis of renal artery stenosis were calculated.Calculate the sensitivity,specificity,accuracy,positive predictive value,and negative predictive value of CRS diagnosis RVH.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of NCE-MRA and CRS combined diagnosis of RVH were calculated.The Fisher probabilities in 2x2 table data methods were used to compare the difference between the NCE-MRA combined with CRS in diagnosing RVH and CRS alone in diagnosing RVH.When P was less than 0.05,the difference was considered statistically significant.Results1.NCE-MRA diagnosis of renal artery stenosis and consistency analysis with DSA diagnosis.NCE-MRA 3 70% of patients with 26 cases,(27)70% of patients with 26 cases,DSA 3 70% of patients with 27 cases,(27)70% of patients with 25 cases,using spearman rank correlation analysis NCE-MRA and DSA for the diagnosis of renal artery stenosis,There was a high consistency between NCE-MRA and DSA in the diagnosis of renal artery stenosis(RAS)(r = 0.808,P< 0.01).The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of NCE-MRA for diagnosis of renal artery stenosis were 88.89%(24/27),92.00%(23/25),90.38%(47/52),92.31%(24/26)and 88.46%(23/26),respectively.2.CRS diagnosis of RVH.DSA renal artery stenosis 3 70% was the criteria for the diagnosis of RVH,DSA 3 70% 27 cases,<70% 25 cases;CRS positive 29 cases,negative 23 cases.The sensitivity of CRS diagnosis of RVH was 81.48%(22/27),the specificity was 72.00%(18/25),the accuracy was 76.92%(40/52),the positive predictive value was 75.86%(22/29),and the negative predictive value was 78.26%(18/23).3.NCE-MRA combined with CRS for the diagnosis of RVH.Twenty-six patients with MRA stenosis 370% were screened from 52 patients,including 20 patients with CRS positive,6 patients with CRS negative,24 patients with DSA renal artery stenosis 370%,and 2 patients with DSA renal artery stenosis <70%.DSA renal artery stenosis 370% was the criteria for diagnosis of RVH,The sensitivity of MRA combined with CRS(Fisher exact probability method,P= 0.046)diagnosis of RVH was 83.33%(20/24),the specificity was 2/2,the accuracy was 84.62%(22 /26),the positive predictive value was 100%(20/20),and the negative predictive value was 2/6.The combined diagnosis of RVH compared with CRS alone,The sensitivity(Fisher exact probability method,P =1.00),specificity(Fisher exact probability method,P =1.00),accuracy(c2=0.629,P=0.428),positive predictive value(Fisher's exact probability method,P =0.03)were all improved,and positive predictive value was statistically significant improved.Conclusion1.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of NCE-MRA in the diagnosis of renal artery stenosis were 88.89%,92.00%,90.38%,92.31% and 88.46%,respectively;and NCE-MRA and DSA have good consistency in diagnosing renal artery stenosis;2.CRS as a functional examination method,the sensitivity,specificity,accuracy,positive predictive value and negative predictive value of RVH diagnosis were 81.48%,72.00%,76.92%,75.86% and 78.26%,respectively;3.NCE-MRA and CRS are effective screening methods for the diagnosis of RVH.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of NCE-MRA combined with CRS diagnosis of RVH were 83.33%? 2/2?84.62%?100%?2/6,respectively;The sensitivity,specificity,accuracy and positive predictive value were higher than that of CRS alone,and the positive predictive value is significant difference,so the combined application of the two tests can significantly improve the diagnostic rate and positive predictive value of RVH.