“…On the other hand, a different resistance index (dRI) due to different degrees of renal parenchymal damage on the two sides results in measurement errors. The AT also confirms this with poor sensitivities (around 50 %) and good specificities (around 95 %) [ 8 , 27 ] in < 80 % RAS. Fig.…”
Section: Significance Of Color-coded Duplex Sonography In the Detectisupporting
confidence: 54%
“…Studies conducted using CCDS (mostly after 1993) generally set the cut-off at 180–200 cm/s [ 8 , 19 , 24 , 27 , 40 , 42 ]. As peak velocities are determined using receiver operating characteristics (ROC) curves, they also always represent an evaluation performed by the author to assess sensitivity or specificity, positive predictive value (PPV) or negative predictive value (NPV).…”
Section: Significance Of Color-coded Duplex Sonography In the Detectimentioning
confidence: 99%
“…To improve the inadequate sensitivities and specificities still seen in some studies, a number of authors recommend combining measurement results from a variety of (direct and indirect) stenosis criteria. In the study conducted by Staub et al combining PSV and RAR yielded sensitivities and specificities of approximately 90 % [ 8 , 24 , 42 ] using a PSV of > 180 cm/s or 200 cm/s and an RAR of 3.5. Abu Rahma [ 1 ] described the combination of a PSV of > 285 cm/s and an RAR of > 3.5 as a viable criterion in renal artery diagnostics with a sensitivity of only 60 % but a specificity of 94 %, whereby this comparison was made with an angiographic stenosis of over 60 %.…”
Background and purposeAs a non-invasive, side effect-free and cost-effective method, ultrasonography represents the method of choice for the diagnosis of renal artery stenosis. Four different criteria in total, including two direct criteria in peak systolic velocity (PSV) and renal aortic ratio (RAR) and two indirect criteria in resistance index (RI) and acceleration time (AT) for the measurement of relevant renal artery stenosis are described, each demonstrating highly variable accuracy in studies. Furthermore, there is controversy over the degree beyond which stenosis becomes therapeutically relevant and which ultrasound PSV is diagnostically relevant in terms of stenosis grading.Material and methodsThis article gives a critical review based on a selective literature search on measurement methodology and the validity of ultrasound in renal artery stenosis. A critical evaluation of methods and a presentation of measurement principles to establish the most precise measurement method possible compared with the gold standard angiography, as well as an evaluation of the importance of computed tomography angiography (CTA) and magnetic resonance angiography (MRA).Results and conclusionsThe PSV provides high sensitivity and specificity as a direct measurement method in stenosis detection and grading. Most studies found sensitivities and specificities of 85–90 % for > 50 % stenosis at a PSV > 180–200 cm/s in ROC curve analysis. Other methods, such as the ratio of the PSV in the aorta to the PSV in the renal artery (RAR) or indirect criteria, such as side to side differences in RI (dRI) or AT can be additionally used to improve accuracy. Contrast-enhanced ultrasound improves accuracy by means of echo contrast enhancement. Although in the past only high-grade stenosis was considered relevant for treatment, a drop in pressure of > 20 mmHg in > 50 % stenosis (PSV 180 cm/s) is classified as relevant for increased renin secretion. Stenosis in fibromuscular dysplasia can be reliably graded according to the continuity equation. Although the available studies on the grading of in-stent restenosis are the subject of controversy, there is a tendency to assume higher cut-off values for PSV and RAR. Whilst MRA and CTA demonstrate an accuracy of > 90 %, this is at the cost of possible side effects for patients, particularly in the case of pre-existing renal parenchymal damage.Additional online materialThis article includes two additional video sequences on visualizing renal artery stenosis. This supplemental material can be found under: dx.doi.org/10.1007/s00772-015-0060-3
“…On the other hand, a different resistance index (dRI) due to different degrees of renal parenchymal damage on the two sides results in measurement errors. The AT also confirms this with poor sensitivities (around 50 %) and good specificities (around 95 %) [ 8 , 27 ] in < 80 % RAS. Fig.…”
Section: Significance Of Color-coded Duplex Sonography In the Detectisupporting
confidence: 54%
“…Studies conducted using CCDS (mostly after 1993) generally set the cut-off at 180–200 cm/s [ 8 , 19 , 24 , 27 , 40 , 42 ]. As peak velocities are determined using receiver operating characteristics (ROC) curves, they also always represent an evaluation performed by the author to assess sensitivity or specificity, positive predictive value (PPV) or negative predictive value (NPV).…”
Section: Significance Of Color-coded Duplex Sonography In the Detectimentioning
confidence: 99%
“…To improve the inadequate sensitivities and specificities still seen in some studies, a number of authors recommend combining measurement results from a variety of (direct and indirect) stenosis criteria. In the study conducted by Staub et al combining PSV and RAR yielded sensitivities and specificities of approximately 90 % [ 8 , 24 , 42 ] using a PSV of > 180 cm/s or 200 cm/s and an RAR of 3.5. Abu Rahma [ 1 ] described the combination of a PSV of > 285 cm/s and an RAR of > 3.5 as a viable criterion in renal artery diagnostics with a sensitivity of only 60 % but a specificity of 94 %, whereby this comparison was made with an angiographic stenosis of over 60 %.…”
Background and purposeAs a non-invasive, side effect-free and cost-effective method, ultrasonography represents the method of choice for the diagnosis of renal artery stenosis. Four different criteria in total, including two direct criteria in peak systolic velocity (PSV) and renal aortic ratio (RAR) and two indirect criteria in resistance index (RI) and acceleration time (AT) for the measurement of relevant renal artery stenosis are described, each demonstrating highly variable accuracy in studies. Furthermore, there is controversy over the degree beyond which stenosis becomes therapeutically relevant and which ultrasound PSV is diagnostically relevant in terms of stenosis grading.Material and methodsThis article gives a critical review based on a selective literature search on measurement methodology and the validity of ultrasound in renal artery stenosis. A critical evaluation of methods and a presentation of measurement principles to establish the most precise measurement method possible compared with the gold standard angiography, as well as an evaluation of the importance of computed tomography angiography (CTA) and magnetic resonance angiography (MRA).Results and conclusionsThe PSV provides high sensitivity and specificity as a direct measurement method in stenosis detection and grading. Most studies found sensitivities and specificities of 85–90 % for > 50 % stenosis at a PSV > 180–200 cm/s in ROC curve analysis. Other methods, such as the ratio of the PSV in the aorta to the PSV in the renal artery (RAR) or indirect criteria, such as side to side differences in RI (dRI) or AT can be additionally used to improve accuracy. Contrast-enhanced ultrasound improves accuracy by means of echo contrast enhancement. Although in the past only high-grade stenosis was considered relevant for treatment, a drop in pressure of > 20 mmHg in > 50 % stenosis (PSV 180 cm/s) is classified as relevant for increased renin secretion. Stenosis in fibromuscular dysplasia can be reliably graded according to the continuity equation. Although the available studies on the grading of in-stent restenosis are the subject of controversy, there is a tendency to assume higher cut-off values for PSV and RAR. Whilst MRA and CTA demonstrate an accuracy of > 90 %, this is at the cost of possible side effects for patients, particularly in the case of pre-existing renal parenchymal damage.Additional online materialThis article includes two additional video sequences on visualizing renal artery stenosis. This supplemental material can be found under: dx.doi.org/10.1007/s00772-015-0060-3
“…Circulatory parameters in the retrobulbar blood vessels are one of them. [34567] Hypertension alters vascular resistance in eyes, and is a major risk factor for arteriosclerosis, and advanced arteriosclerosis occurs with increasing age which indicates long duration of hypertension. Previously, a little number of studies in literature has been performed to evaluate the RIs of orbital arteries in patients with hypertension.…”
Background and Aim:Resistive index (RI) is an indirect measurement of blood flow resistance that can be used to evaluate vascular damage in ophthalmologic disease. The purpose of this study was to evaluate the association between RI values of orbital arteries using the color Doppler imaging (CDI) in geriatric hypertensive patients with or without retinopathy.Setting and Design:Designed as a cross-sectional study.Materials and Methods:We evaluated 60 geriatric patients with hypertension (Group 1) and 30 healthy subjects (Group 2). Further, the patients with hypertension were grouped into two: Group 1a consisted of patients with retinopathy (n = 30), and group 1b consisted of patients without retinopathy (n = 30). The mean RI values of ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery (PCA) were measured using CDI.Results:Compared to group 2, group 1 had significantly higher mean resistive index of PCA levels (P = 0.017), whereas there were no statistical difference in mean resistive indexes of OA and CRA (both P > 0.05). Besides, there were no statistical difference in mean resistive indexes of OA, CRA, and PCA between the group 1a and group 1b (P > 0.05 for all). Mean resistive indexes of OA, CRA, and PCA were significantly correlated with the duration of hypertension (r = 0.268, P = 0.038; r = 0.315, P = 0.014; r = 0.324, P = 0.012, respectively).Conclusions:Our study indicates that RI might be a useful marker for the ocular hemodynamic of retinal vessels, provides morphologic and vascular information in hypertension and hypertensive retinopathy.
“…This may be seen unilaterally, distal to a severe RAS, or bilaterally in mid-aortic syndrome (MAS) or coarctation [11, 13, 14]. As in adults, a less severe stenosis of the main renal artery may lead to loss of laminar flow and increased PSV [15], and a ratio of renal-to-aortic velocity greater than 3.0 or 3.5 might also be indicative of RAS [13, 15]. …”
Renovascular disease (RVD) is an important cause of hypertension in children, as it often is amenable to potentially curative treatment. Imaging aimed at finding RVD therefore needs to have high sensitivity so as not to miss important findings. Digital subtraction angiography is the gold standard investigation. Doppler ultrasonography, computed tomography (CT) angiography and magnetic resonance (MR) angiography can all be helpful, but none has, at present, high enough sensitivity to rule out RVD in a child with a suggestion of that diagnosis.
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