Gold Standard Digital Subtraction Angiography Research Articles

Role of Contrast-Enhanced Ultrasound in the Evaluation of Patients With Suspected Renal Arterial Stenosis.

ObjectivesTo explore the role of Contrast-enhanced ultrasound (CEUS) in the evaluation of patients with suspected renal artery stenosis and analyze the causes of the misdiagnosis and missed diagnosis.MethodsThe data of 40 patients (80 renal arteries) diagnosed with RAS by CEUS in Beijing Hospital from September 2018 to October 2020 were compared with their digital subtraction angiography (DSA) results to analyze the causes underlying missed diagnosis and misdiagnosis of RAS by CEUS.Results1. Compared with the gold standard DSA results, the AUC of the ROC curve of CEUS in detecting normal renal artery and renal artery stenosis was 0.961, the sensitivity was 96.4%, the specificity was 95.8%, and the Kappa value of the consistency analysis was 0.912 (P < 0.01); 2. Compared with the gold standard DSA results, the ROC curve of CEUS in distinguishing renal artery stenosis ≥70% from <70% stenosis has an AUC of 0.916, a sensitivity of 90.9%, a specificity of 92.3%, and the Kappa value of the consistency analysis is 0.77 (P < 0.01); 3. CEUS missed two cases (one for mild stenosis and one for moderate stenosis), and the detection rate of renal artery stenosis was 97.5% (78/80); A total of 65 renal arteries diagnosed by CEUS were consistent with DSA, and the diagnostic accuracy of CEUS for the degree of stenosis was 81.25% (65/80); Among the 13 misdiagnosed renal arteries, 4 of them can be corrected to the same degree as DSA by the reference to hemodynamic index, and the diagnosis rate of the degree of renal artery stenosis by ultrasonography (combined with CEUS and hemodynamic indicators) can be improved to 86.25%.Conclusions1. CEUS can clearly show the renal arteries, and is consistent with DSA in distinguishing normal renal artery stenosis from renal artery stenosis, as well as renal artery stenosis ≥70% and <70% stenosis; 2. CEUS showed good performance in detecting normal renal artery and renal artery stenosis, and the missed diagnosis is concentrated on mild and moderate stenosis; 3. CEUS combined with hemodynamic indicators (Doppler ultrasound) can improve the accurate diagnosis rate of renal artery stenosis by ultrasonography; 4. The most important factor for the accurate diagnosis of renal artery stenosis by CEUS is the operator's standardized examination, which is not only related to the duration of the operator has been engaged in this inspection, but also related to whether the operator has received professional training in relevant aspects. These all indicate the necessity and importance of the standardized operation of renal artery contrast-enhanced ultrasound examination, and professional training should be given to operators.

Current Perspectives in Imaging Modalities for the Assessment of Unruptured Intracranial Aneurysms: A Comparative Analysis and Review

Intracranial aneurysms (IAs) are pathologic dilatations of cerebral arteries. This systematic review summarizes and compares imaging techniques for assessing unruptured IAs (UIAs). This review also addresses their uses in different scopes of practice. Pathophysiologic mechanisms are reviewed to better understand the clinical usefulness of each imaging modality. A literature review was performed using PubMed with these search terms: "intracranial aneurysm," "cerebral aneurysm," "magnetic resonance angiography (MRA)," computed tomography angiography (CTA)," "catheter angiography," "digital subtraction angiography," "molecular imaging," "ferumoxytol," and "myeloperoxidase". Only studies in English were cited. Since the development and improvement of noninvasive diagnostic imaging (computed tomography angiography and magnetic resonance angiography), many prospective studies and meta-analyses have compared these tests with gold standard digital subtraction angiography (DSA). Although computed tomography angiography and magnetic resonance angiography have lower detection rates for UIAs, they are vital in the treatment and follow-up of UIAs. The reduction in ionizing radiation and lack of endovascular instrumentation with these modalities provide benefits compared with DSA. Novel molecular imaging techniques to detect inflammation within the aneurysmal wall with the goal of stratifying risk based on level of inflammation are under investigation. DSA remains the gold standard for preoperative planning and follow-up for patients with IA. Newer imaging modalities such as ferumoxytol-enhanced magnetic resonance imaging are emerging techniques that provide critical invivo information about the inflammatory milieu within aneurysm walls. With further study, these techniques may provide aneurysm rupture risk and prediction models for individualized patient care.

Assessment of intracranial venous blood flow after subarachnoid hemorrhage: a new approach to diagnose vasospasm with transcranial color-coded duplex sonography.

OBJECTIVETranscranial color-coded duplex sonography (TCCS) is a reliable tool that is used to assess vasospasm in the M1 segment of the middle cerebral artery (MCA) after subarachnoid hemorrhage (SAH). A distinct increase in blood flow velocity (BFV) is the principal criterion for vasospasm. The MCA/internal carotid artery (ICA) index (Lindegaard Index) is also widely used to distinguish between vasospasm and cerebral hyperperfusion. However, extracranial ultrasonography assessment of the neck vessels might be difficult in an intensive care unit. Therefore, the authors evaluated whether the relationship of intracranial arterial to venous BFV might indicate vasospasm with similar or even better accuracy.METHODSPatients who presented between 2008 and 2015 with aneurysmal SAH were prospectively enrolled in the study. Digital subtraction angiography (DSA) and TCCS were performed within 24 hours of each other to assess vasospasm 8-10 days after SAH. The following different TCCS parameters were analyzed to assess vasospasm in the MCA and were compared with the gold-standard DSA parameters: 1) mean time-averaged maximum BFV (Vmean) of the MCA, 2) peak systolic velocity (PSV) of the MCA, 3) the Lindegaard Index using Vmean as well as PSV, and 4) a new arteriovenous index (AVI) between the MCA and the basal vein of Rosenthal using Vmean and PSV. The best cutoff values for these parameters to distinguish vasospasm from normal perfusion or hyperperfusion were calculated using receiver operating characteristic curve analysis. Sensitivity, specificity, positive predictive value, and negative predictive value as well as the overall accuracy for each cutoff value were analyzed.RESULTSA total of 102 patients (mean age 52 ± 12 years) were evaluated. Bilateral MCA assessment by TCCS was successful in all patients. In 6 cases (3%), the BFV of the basal vein of Rosenthal could not be analyzed. The AVI could not be calculated in 50 of 204 cases (25%) because the insonation quality was very low in one of the ICAs. An AVI > 10 for Vmean and an AVI > 12 for systolic velocity provided the highest accuracies of 87% and 86%, respectively. Regarding the Lindegaard Index, the accuracy was highest using a threshold of > 3 for the mean BFV (84%) as well as systolic BFV (80%). BFVs in the MCA of ≥ 120 cm/sec (Vmean) and ≥ 200 cm/sec (PSV) predicted vasospasm with accuracies of 84% and 83%, respectively. A combined analysis of the MCA BFV and the AVI led to a slight increase in specificity (Vmean, 94%; PSV, 93%) and positive predictive value (Vmean, 88%; PSV 86%) without further improvement in accuracy (Vmean, 88%; PSV, 84%).CONCLUSIONSThe intracranial AVI is a reliable parameter that can be used to assess vasospasm after SAH. Its reliability for differentiating vasospasm and hyperperfusion is slightly higher than that for the established Lindegaard Index, and this method has the additional advantage of a remarkably lower failure rate.

Planning-free cerebral blood flow territory mapping in patients with intracranial arterial stenosis

A noninvasive method for quantifying cerebral blood flow and simultaneously visualizing cerebral blood flow territories is vessel-encoded pseudocontinuous arterial spin labeling MRI. However, obstacles to acquiring such information include limited access to the methodology in clinical centers and limited work on how clinically acquired vessel-encoded pseudocontinuous arterial spin labeling data correlate with gold-standard methods. The purpose of this work is to develop and validate a semiautomated pipeline for the online quantification of cerebral blood flow maps and cerebral blood flow territories from planning-free vessel-encoded pseudocontinuous arterial spin labeling MRI with gold-standard digital subtraction angiography. Healthy controls (n = 10) and intracranial atherosclerotic disease patients (n = 34) underwent 3.0 T MRI imaging including vascular (MR angiography) and hemodynamic (cerebral blood flow-weighted arterial spin labeling) MRI. Patients additionally underwent catheter and/or CT angiography. Variations in cross-territorial filling were grouped according to diameters of circle of Willis vessels in controls. In patients, Cohen’s k-statistics were computed to quantify agreement in perfusion patterns between vessel-encoded pseudocontinuous arterial spin labeling and angiography. Cross-territorial filling patterns were consistent with circle of Willis anatomy. The intraobserver Cohen's k-statistics for cerebral blood flow territory and digital subtraction angiography perfusion agreement were 0.730 (95% CI = 0.593–0.867; reader one) and 0.708 (95% CI = 0.561–0.855; reader two). These results support the feasibility of a semiautomated pipeline for evaluating major neurovascular cerebral blood flow territories in patients with intracranial atherosclerotic disease.

A novel method to assess pial collateralization from stroke perfusion MRI:subdividing Tmax into anatomical compartments.

To develop and validate a quantitative and observer-independent method to evaluate pial collateral circulation by DSC-perfusion MRI and test whether this novel method delivers diagnostic information which is redundant to or independent from conventional penumbra imaging by the mismatch approach. We retrospectively identified 47 patients with M1 occlusion who underwent MR diffusion/perfusion imaging and mechanical thrombectomy at our facility. By automated registration and segmentation, Tmax delays were attributed specifically to the pial, cortical and parenchymal compartments. The resulting pial volumes at delay were defined as the pial Tmax map-assessed collateral score (TMACS) and correlated with gold standard digital subtraction angiography (DSA). Mismatch ratio was assessed by conventional penumbra defining MRI criteria. Strong correlation was found between TMACS and angiographically assessed collateral score (Pearson ρ = -0.74, p < 0.001). In multiple logistic regression, both good collaterals according to TMACS [OR 4.3 (1.1-19, p = 0.04)] and mismatch ratio ≥ 3.5 [OR 12.3 (1.88-249, p = 0.03)] were independent predictors of favourable clinical outcome. Perfusion delay in the pial compartment, as evaluated by TMACS, closely reflects the extent of pial collaterals in gold-standard DSA. TMACS and mismatch ratio were found to be complementary predictors of a favourable clinical outcome, each adding independent predictive information. • MRI-DSC perfusion delay specific in the pial compartment reflects leptomeningeal collateralization. • A novel quantitative- and observer-independent marker of collateral status (TMACS) is introduced. • Quantification of collateral status leads to an independent predictor of neurological outcome.

The application of susceptibility-weighted MRI in pre-interventional evaluation of intracranial dural arteriovenous fistulas

Background and purposeDetection and characterization of intracranial dural arteriovenous fistula (DAVF) is important to plan appropriate therapeutic management. The aim of this study was to analyze the utility of susceptibility-weighted...

Contrast-enhanced CT and MR imaging of renal vessels

In the evaluation of renal vessels, the accepted diagnostic gold standard digital subtraction angiography is now being challenged by state of the art CT and MR imaging. Currently in many centers, cross-sectional imaging modalities are being used as a first line diagnostic tool to evaluate arterial and venous system of the kidneys and conventional angiography has been reserved only for therapeutic intervention. CT and MR imaging display not only the lumen of the vessel as in conventional angiography, but also allow the visualization of the vessel wall, renal parenchyma, collecting system, and other adjacent soft tissue structures. Therefore, CT and MRI have each become a one-stop shop for a thorough evaluation of kidneys. In this pictorial essay, we reviewed normal anatomical variants and wide range of pathologies involving renal arteries and veins with illustrated contrast-enhanced CT and MR imaging samples.

Grading of Carotid Artery Stenosis in the Presence of Extensive Calcifications: Dual-Energy CT Angiography in Comparison with Contrast-Enhanced MR Angiography

We investigated the agreement of dual-energy computed tomography angiography (DE-CTA) and contrast-enhanced magnetic resonance angiography (CE-MRA)in the quantitative measurement of stenoses of the internal carotid artery in comparison with digital subtraction angiography (DSA). A total of 21 patients with stenoses of the external carotid artery were investigated with a DE-CTA and CE-MRA before undergoing carotid angioplasty. The grade of the stenoses was assessed in axial multiplanar reformations (MPR) before and multi-intensity projections (MIP) after plaque subtraction (PS) and compared with results from CE-MRA and DSA according to the North American Symptomatic Carotid Endarterectomy Trial. Average grades of stenoses were 80.7 ± 16.1 % (DSA), 81.4 ± 15.3 % (MRA), 80.0 ± 16.7 % (DE-CTA-MPR), and 85.2 ± 14.7 % (DE-CTA-PS-MIP). Of 21 stenoses, 6 were filiform (stenosis grade, 99 %) in the DSA examination. Five of these cases were identified as pseudo-occlusions in MRA, while four were considered as occlusions in DE-CTA-PS-MIP. Another four cases were identified as pseudo-occlusion in DE-CTA-PS-MIP, which were identified as 90 % stenosis in the DSA examination. In comparison with the gold standard DSA, DE-CTA-MPR had a slightly better agreement in measuring the degree of stenosis of the internal carotid arteries than CE-MRA. In DE-CTA-PS-MIP images, a systematic overestimation has to be taken into account due to partial extinction of the lumen by the PS algorithm. Nevertheless, DE-CTA should be preferred in imaging patients with carotid artery stenosis in the presence of extensive calcifications.

Bone subtraction CT angiography for the detection of intracranial aneurysms

The aim of the study was to retrospectively analyse the accuracy of CT angiography (CTA) of the Circle of Willis and a prototype bone subtraction CT angiogram (BSCTA) compared with digital subtraction angiography (DSA) in the detection of intracranial aneurysms. A total of 36 patients with suspected subarachnoid haemorrhage who had CTA scans that had matching DSA studies between November 2005 and December 2006 were retrospectively reviewed by two experienced neurointerventionalist. Three-dimensional volume-rendered (3D VR) CTA and BSCTA were reviewed, followed by review of the source data in multi-planar reformats (MPRs). The results were then assessed for sensitivity and specificity compared with the gold standard DSA. Time taken to review the studies, visibility of the ophthalmic, posterior communicating arteries, superior cerebella artery, posterior cerebral artery on the 3D VR BSCTA and CTA were analysed. BSCTA was assessed for residual bone and artificial stenosis. Further, the aneurysms were analysed for suitability of endovascular treatment versus surgical treatment based on CTA and BSCTA with MPR and 3D VR. CTA 3D VR sensitivity and specificity was 94 and 80%, respectively. CTA MPR sensitivity and specificity was 100% and 90%, respectively. When both CTA 3D VR and MPR images were combined the sensitivity and specificity was 100 and 90%, respectively. BSCTA 3D VR sensitivity and specificity was 91 and 90%, respectively, and the MPR sensitivity and specificity was 97 and 90%, respectively. When both BSCTA 3D VR and MPR images were combined the sensitivity was 97% with a specificity of 90% Overall, an 84% correlation was found between both CTA and BSCTA when compared with DSA for assessing for suitability of endovascular treatment versus surgical treatment. A statistically significant difference was shown between the time taken to review the CTA and BSCTA (P < 0.001 confidence interval 3.1-3.9 min). In this study there was no significant difference between the diagnostic ability of BSCTA compared with CTA. Importantly, both CTA and BSCTA had high sensitivities and specificities compared to DSA.

Graph-matching-based computed tomography angiography in peripheral arterial occlusive disease

The objective of this study is to compare a graph-matching-based software and a conventional tool for postprocessing of computed tomography angiography (CTA) in correlation with the gold standard digital subtraction angiography. Sensitivity, specificity, accuracy, and interobserver agreement increased from 80.3% to 92.9%, from 69.1% to 92.4%, from 73.5% to 92.8%, and from 0.45 to 0.96, respectively, using the graph-matching-based technique. Graph-matching-based CTA increases sensitivity, specificity, accuracy, and interobserver agreement in comparison to a conventional bone elimination tool in the assessment of peripheral arterial occlusive disease.

CT-Diagnostik bei Karotisstenose

CT angiography can be used to evaluate carotid artery stenosis with high diagnostic safety. In contrast to the gold standard digital subtraction angiography (DSA) it is a non-invasive procedure which yields information regarding the degree of stenosis as well as information about plaque morphology. Due to multiple reconstruction planes in 3 levels in maximum intensity projections (MIP) and the possibility to perform volume rendering (VR) reconstruction more information about the extent of carotid disease can be acquired. Due to the bolus tracking technique optimum contrast medium enhancement of the carotid artery with simultaneous minimization of venous artifacts is possible.

Meta-Analysis on Diagnostic Accuracy of MR Angiography in the Follow-up of Residual Intracranial Aneurysms Treated with Guglielmi Detachable Coils

Patients with intracranial aneurysm after coiling with Guglielmi detachable coils (GDC) require imaging follow-up. The accuracy of noninvasive magnetic resonance angiography (MRA) techniques including time-of-flight (TOF) and contrast-enhancement (CE) have been compared with the gold standard digital subtraction angiography (DSA).We systematically reviewed the diagnostic accuracy of these imaging methods in follow-up study of patients with residual intracranial aneurysms after GDC treatment. The authors used MEDLINE, bibliographies, review articles, textbooks, and expert opinion to retrieve English- and non-English-language articles published from 1966 to December 2007. Sixteen suitable MRA original articles (14 TOFMRA and six CE-MRA) with comparison to DSA have met the inclusion criteria. TOF-MRA had a pooled sensitivity of 90% (95% CI, 79% to 95%), a specificity of 95% (95% CI, 88% to 98%), and a diagnostic odds ratio (DOR) of 168.4 (95% CI, 60.3 to 470.3). CE-MRA had an overall sensitivity of 92% (95% CI, 79% to 97%), a specificity of 96% (95% CI, 91% to 98%), and a DOR of 280.4 (95% CI, 64.8 to 1212.6). The areas under two summary ROC curves of TOF-MRA and CE-MRA were 0.97 (95% CI, 0.96 to 0.99) and 0.98 (95% CI, 0.96 to 0.99), respectively. Compared with DS angiography, both TOF-MRA and CE-MRA can accurately depict the residual aneurysm. The diagnostic accuracy of TOF-MRA and CE-MRA tests offer comparable and equal results and may obviate the invasive DS angiography.

Inferring origin of vascular supply from tracer arrival timing patterns using bolus tracking MRI

To investigate the potential of novel postprocessing and visualization techniques to distinguish presence of collateral flow using Bolus Tracking MRI. Collateral blood supply is believed to be of paramount importance in acute stroke, yet clinical evaluation is challenging as the gold standard digital subtraction angiography is often not feasible in the acute scenario. In principle, bolus arrival delay data contains information about the route of blood supply into tissue and hereby presence of collateral flow patterns. We first examined the potential of current clinical bolus tracking protocols to accurately characterize bolus arrival delay. Using the simulation results, we analyzed bolus tracking data from one normal volunteer and one acute stroke patient. The bolus arrival patterns in the volunteer and in the normal hemisphere of the patient were found to be qualitatively similar and in good agreement with physiology. The bolus was seen to spread from the larger arteries toward the periphery. The stroke hemisphere in the patient indicated a retrograde direction of flow on the cortical mantle consistent with leptomeningeal vessels. Bolus tracking MRI can likely be used to distinguish collateral flow patterns from normal flow patterns.