Comparison of carotid Doppler ultrasound and computerised tomographic angiography in the evaluation of carotid artery stenosis

A Comparative Analysis and Results of Carotid Interventions Based on Duplex Ultrasound as a Single Exam Versus Multiple Diagnose Exams

BACKGROUND

To determine the results, safety, and clinical outcomes of carotid interventions performed with duplex ultrasound (DUS) as a single preoperative image for internal carotid artery (ICA) assessment, compared to computed tomography angiography (CTA) and magnetic resonance angiography (MRA).

METHODS

Prospective, consecutive cohort study of 2 groups of patients submitted to carotid interventions, 1 group of patients with DUS as a sole exam (group DUS) compared to patients with DUS plus CTA or MRA for ICA stenosis diagnosis (group CTA/MRA) regarding clinical outcomes such as major stroke, minor stroke, transient ischemic attack and perioperative mortality.

RESULTS

Two groups of patients were identified: group DUS with 47 patients and group CTA/MRA plus DUS with 68 patients. The mean age of the patients was 71.67 years in total cohort, and most of them were male (66.1%). Group DUS had higher prevalence of male, dyslipidemia, ischemic heart disease, peripheral artery disease and chronic kidney disease than group CTA/MRA (83% vs. 54.4%, P = 0.001; 93.6% vs. 51.5%, P < 0.001; 36.2% vs. 16.2%, P = 0.009; 29.8% vs. 13.2%, P = 0.019; 14.9% vs. 5.9%, P = 0.007, respectively). We have performed a Kaplan-Meier regarding survival rates: Group DUS had 93.5%% and Group CTA/MRA had 90.3%% at 720 days. P = 0.15, standard error < 10 at 720 days. a Kaplan-Meier analysis regarding primary patency rates showed Group DUS with 92.7% and Group CTA/MRA with 94.7% at 720 days. P = 0.78, standard error < 10 at 720 days. Furthermore, the incidence of postoperative stroke was 2.6% (asymptomatic 1.7%, symptomatic 2.9%), with no differences among DUS and CTA/MRA groups (2.1% vs. 2.9%, P = 0.78, respectively).

CONCLUSIONS

Independently of the type of carotid intervention (carotid endarterectomy and carotid stenting (CAS)), DUS as an only preoperative carotid image has similar results regarding postoperative outcomes when compared to CTA/MRA for preoperative carotid evaluation.

Comparison of Doppler Ultrasound and Computerized Tomographic Angiography in Evaluation of Cervical Arteries Stenosis in Stroke Patients, a Retrospective Single-Center Study

There are different diagnostic modalities to investigate atherosclerosis cervical artery disease in suspected stroke patients. We aimed to test the concordance of findings of the two most widely used diagnostic modalities in stroke patients: duplex ultrasound (DUS) and computerized tomographic angiography (CTA). A total of 100 stroke patients were retrospectively included in the study, all of them had DUS followed by CTA. Discrepancies of DUS compared to the CTA results in both the internal carotid and vertebral arteries were found in 44% of the patients. The patients with significant differences in diagnostic results were characterized by older age. Evaluation of the degree of carotid artery stenosis revealed vast differences in patients with 50-69% stenosis found by DUS, in which 45.5% of them had a different percentage of stenosis found by CTA. In studying the degree of stenosis of the vertebral artery, only 47.1% of the patients with more than 50% stenosis found by DUS had the same results with CTA, while the remaining revealed normal or less than 50% stenosis by CTA. The current study emphasizes that CTA is more accurate than DUS in the evaluation of stenosis of the cervical arteries including both the internal carotid and vertebral arteries.

Duplex ultrasound for diagnosing symptomatic carotid stenosis in the extracranial segments

BACKGROUND

Carotid artery stenosis is an important cause of stroke and transient ischemic attack. Correctly and rapidly identifying patients with symptomatic carotid artery stenosis is essential for adequate treatment with early cerebral revascularization. Doubts about the diagnostic value regarding the accuracy of duplex ultrasound (DUS) and the possibility of using DUS as the single diagnostic test before carotid revascularization are still debated.

OBJECTIVES

To estimate the accuracy of DUS in individuals with symptomatic carotid stenosis verified by either digital subtraction angiography (DSA), computed tomography angiography (CTA), or magnetic resonance angiography (MRA).

SEARCH METHODS

We searched CRDTAS, CENTRAL, MEDLINE (Ovid), Embase (Ovid), ISI Web of Science, HTA, DARE, and LILACS up to 15 February 2021. We handsearched the reference lists of all included studies and other relevant publications and contacted experts in the field to identify additional studies or unpublished data.

SELECTION CRITERIA

We included studies assessing DUS accuracy against an acceptable reference standard (DSA, MRA, or CTA) in symptomatic patients. We considered the classification of carotid stenosis with DUS defined with validated duplex velocity criteria, and the NASCET criteria for carotid stenosis measures on DSA, MRA, and CTA. We excluded studies that included < 70% of symptomatic patients; the time between the index test and the reference standard was longer than four weeks or not described, or that presented no objective criteria to estimate carotid stenosis.

DATA COLLECTION AND ANALYSIS

The review authors independently screened articles, extracted data, and assessed the risk of bias and applicability concerns using the QUADAS-2 domain list. We extracted data with an effort to complete a 2 × 2 table (true positives, true negatives, false positives, and false negatives) for each of the different categories of carotid stenosis and reference standards. We produced forest plots and summary receiver operating characteristic (ROC) plots to summarize the data. Where meta-analysis was possible, we used a bivariate meta-analysis model.

MAIN RESULTS

We identified 25,087 unique studies, of which 22 were deemed eligible for inclusion (4957 carotid arteries). The risk of bias varied considerably across the studies, and studies were generally of moderate to low quality. We narratively described the results without meta-analysis in seven studies in which the criteria used to determine stenosis were too different from the duplex velocity criteria proposed in our protocol or studies that provided insufficient data to complete a 2 × 2 table for at least in one category of stenosis. Nine studies (2770 carotid arteries) presented DUS versus DSA results for 70% to 99% carotid artery stenosis, and two (685 carotid arteries) presented results from DUS versus CTA in this category. Seven studies presented results for occlusion with DSA as the reference standard and three with CTA as the reference standard. Five studies compared DUS versus DSA for 50% to 99% carotid artery stenosis. Only one study presented results from 50% to 69% carotid artery stenosis. For DUS versus DSA, for < 50% carotid artery stenosis, the summary sensitivity was 0.63 (95% confidence interval [CI] 0.48 to 0.76) and the summary specificity was 0.99 (95% CI 0.96 to 0.99); for the 50% to 69% range, only one study was included and meta-analysis not performed; for the 50% to 99% range, the summary sensitivity was 0.97 (95% CI 0.95 to 0.98) and the summary specificity was 0.70 (95% CI 0.67 to 0.73); for the 70% to 99% range, the summary sensitivity was 0.85 (95% CI 0.77 to 0.91) and the summary specificity was 0.98 (95% CI 0.74 to 0.90); for occlusion, the summary sensitivity was 0.91 (95% CI 0.81 to 0.97) and the summary specificity was 0.95 (95% CI 0.76 to 0.99). For sensitivity analyses, excluding studies in which participants were selected based on the presence of occlusion on DUS had an impact on specificity: 0.98 (95% CI 0.97 to 0.99). For DUS versus CTA, we found two studies in the range of 70% to 99%; the sensitivity varied from 0.57 to 0.94 and the specificity varied from 0.87 to 0.98. For occlusion, the summary sensitivity was 0.95 (95% CI 0.80 to 0.99) and the summary specificity was 0.91 (95% CI 0.09 to 0.99). For DUS versus MRA, there was one study with results for 50% to 99% carotid artery stenosis, with a sensitivity of 0.88 (95% CI 0.70 to 0.98) and specificity of 0.60 (95% CI 0.15 to 0.95); in the 70% to 99% range, two studies were included, with sensitivity that varied from 0.54 to 0.99 and specificity that varied from 0.78 to 0.89. We could perform only a few of the proposed sensitivity analyses because of the small number of studies included.

AUTHORS' CONCLUSIONS

This review provides evidence that the diagnostic accuracy of DUS is high, especially at discriminating between the presence or absence of significant carotid artery stenosis (< 50% or 50% to 99%). This evidence, plus its less invasive nature, supports the early use of DUS for the detection of carotid artery stenosis. The accuracy for 70% to 99% carotid artery stenosis and occlusion is high. Clinicians should exercise caution when using DUS as the single preoperative diagnostic method, and the limitations should be considered. There was little evidence of the accuracy of DUS when compared with CTA or MRA. The results of this review should be interpreted with caution because they are based on studies of low methodological quality, mainly due to the patient selection method. Methodological problems in participant inclusion criteria from the studies discussed above apparently influenced an overestimated estimate of prevalence values. Most of the studies included failed to precisely describe inclusion criteria and previous testing. Future diagnostic accuracy studies should include direct comparisons of the various modalities of diagnostic tests (mainly DUS, CTA, and MRA) for carotid artery stenosis since DSA is no longer considered to be the best method for diagnosing carotid stenosis and less invasive tests are now used as reference standards in clinical practice. Also, for future studies, the participant inclusion criteria require careful attention.

Pictorial Essay of Cervical Duplex Ultrasonography

Objectives: Cervical duplex ultrasonography (CDU) is a simple, non-invasive, portable technique, that provides valuable high-quality visual information about the integrity of the carotid and vertebral vessels, plaque morphology and flow hemodynamics. CDU is useful in the assessment and follow up of patients with cerebrovascular disease as well as other conditions like inflammatory vasculitis, carotid artery dissection and carotid body tumours. CDU is inexpensive and invaluable in smaller centres. Methods: CDU was performed in all patients in both longitudinal and transverse planes in the out-patient clinic. Brightness mode (B-mode) and Doppler waveforms were obtained. Relevant findings were presented. Results: CDU provides real time visualisation of plaque characteristics and follow up, hemodynamic characteristics in Takayasu arteritis, visualisation of dissection. Conclusion: With availability of MR/CT angiography, CDU can be an adjuvant in follow up, triage and early bed-side diagnosis of the vascular diseases. We present our experience with CDU in the out-patient clinics in this pictorial essay.

Association between Oral Pathology, Carotid Stenosis, and Oral Bacterial DNA in Cerebral Thrombi of Patients with Stroke

Methods

Thrombus aspirates and control arterial blood were taken from 71 patients (70.4% male; mean age, 67.4 years) with acute ischemic stroke. Tooth pathology was registered using CT scans. Carotid stenosis was estimated with CTA and ultrasonography. The presence of bacterial DNA from aspirated thrombi was determined using quantitative PCR. We also analyzed the presence of these bacterial DNAs in carotid endarterectomies from patients with peripheral arterial disease.

Results

Bacterial DNA was found in 59 (83.1%) of the thrombus aspirates (median, 8.6-fold). Oral streptococcal DNA was found in 56 (78.9%) of the thrombus aspirates (median, 5.1-fold). DNA from A. actinomycetemcomitans and P. gingivalis was not found. Most patients suffered from poor oral health and had in median 19.0 teeth left. Paradoxically, patients with better oral health had more oral streptococcal DNA in their thrombus than the group with the worst pathology (p = 0.028). There was a trend (OR 7.122; p = 0.083) in the association of ≥50% carotid artery stenosis with more severe dental pathology. Oral streptococcal DNA was detected in 2/6 of carotid endarterectomies.

Conclusions

Stroke patients had poor oral health which tended to associate with their carotid artery stenosis. Although oral streptococcal DNA was found in thrombus aspirates and carotid endarterectomy samples, the amount of oral streptococcal DNA in thrombus aspirates was the lowest among those with the most severe oral pathology. These results suggest that the association between poor oral health and acute ischemic stroke is linked to carotid artery atherosclerosis.

A proof of concept study for machine learning application to stenosis detection

This proof of concept (PoC) assesses the ability of machine learning (ML) classifiers to predict the presence of a stenosis in a three vessel arterial system consisting of the abdominal aorta bifurcating into the two common iliacs. A virtual patient database (VPD) is created using one-dimensional pulse wave propagation model of haemodynamics. Four different machine learning (ML) methods are used to train and test a series of classifiers—both binary and multiclass—to distinguish between healthy and unhealthy virtual patients (VPs) using different combinations of pressure and flow-rate measurements. It is found that the ML classifiers achieve specificities larger than 80% and sensitivities ranging from 50 to 75%. The most balanced classifier also achieves an area under the receiver operative characteristic curve of 0.75, outperforming approximately 20 methods used in clinical practice, and thus placing the method as moderately accurate. Other important observations from this study are that (i) few measurements can provide similar classification accuracies compared to the case when more/all the measurements are used; (ii) some measurements are more informative than others for classification; and (iii) a modification of standard methods can result in detection of not only the presence of stenosis, but also the stenosed vessel.

Graphical Abstract

Preoperative Vascular Planning of Free Flaps: Comparative Study of Computed Tomographic Angiography, Color Doppler Ultrasonography, and Hand-Held Doppler

BACKGROUND

Preoperative planning of microsurgical perforator free flaps continues to be a discussion topic among microsurgeons. The purpose of this study was to compare the ability of three methods of preoperative vascular mapping-hand-held Doppler imaging, color Doppler ultrasonography, and computed tomographic angiography-to detect perforators and their concordance with surgical findings.

METHODS

A prospective study was performed to evaluate the sensitivity, specificity, and accuracy of hand-held Doppler imaging, color Doppler ultrasonography, and computed tomographic angiography to detect free flap perforators. Each patient undergoing a free flap reconstruction was studied preoperatively with the three methods, and the results were compared to the intraoperative findings.

RESULTS

Fifty-three patients undergoing autologous tissue reconstruction were included. Most reconstructions (71.7 percent) were performed with anterolateral thigh flaps. The positive predictive value (color Doppler ultrasonography, 100 percent; computed tomographic angiography, 100 percent; hand-held Doppler imaging, 88.6 percent) and negative predictive value (color Doppler ultrasonography, 100 percent; computed tomographic angiography, 94.3 percent; hand-held Doppler imaging, 90.5 percent) rates were significantly different between methods. The high resolution of the color Doppler ultrasonography probe provided a direct vision of the vasculature arborization and efficiently detected vessels with diameters of less than 0.5 mm. The sensitivity, specificity, and accuracy of color Doppler ultrasonography were greater than those of both computed tomographic angiography and hand-held Doppler imaging. There was 100 percent concordance between color Doppler ultrasonography perforators and the surgical findings.

CONCLUSIONS

Color Doppler ultrasonography provides a reproducible, harmless, and accurate way to visualize vascular anatomy. It has a high correlation with the surgical findings, signifying advantages over hand-held Doppler and computed tomographic angiography in sensitivity, specificity, and accuracy.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

Assesment of Carotid Stenosis with CT Angiography and Color Doppler Ultrasonography

Introduction:

Color Doppler and CT angiography are diagnostic methods commonly used to determine the degree of carotid stenosis.

Aim:

To evaluate how the degree of carotid stenosis determined by the Color Doppler correlates with the degree of stenosis determined by the CT angiography.

Material and Methods:

The study was designed as a retrospective study. It included 42 patients with carotid stenosis. From medical records we collected anamnestic data (gender, age and risk factors - hypertension, hyperlipidemia, diabetes, smoking and obesity) and the results regarding the degree of carotid stenosis determined by Color Doppler and CT angiography.

Results:

Out of the total number of patients (n=42), 73.8% were males and 26.2% were females. Average age of examined patients was 65.24±8.61. Most frequent risk factor of atherosclerosis was hypertension, followed by hyperlipidemia and smoking. NASCET grading distinguishes: first (0-29%), second (30-69%) and third (70-99%) degree of carotid stenosis. According to the Color Doppler evaluation findings, the second degree had 8 patients and 34 patients had the third degree of carotid stenosis. CT angiography have shown that 35 patients had third degree carotid stenosis, while 7 patients had the second degree carotid stenosis. In only one case results of evaluated methods differed regarding assessment of carotid stenosis. We have found that there is a significant positive correlation of the degree of carotid stenosis determined by the Color Doppler with the degree of stenosis determined by CT angiography (p=0.0002). Risk factors of atherosclerosis did not have a significant correlation with the degree of carotid stenosis (p>0.05).

Conclusion:

The degree of carotid stenosis estimated by the Color Doppler positively correlates with the degree of stenosis estimated by CT angiography.

The Relation of Calcium Volume Score and Stenosis of Carotid Artery

OBJECTIVE

The aim of this study was to investigate the value of extracranial carotid artery calcium score in predicting severity of carotid arterial stenosis.

MATERIAL AND METHODS

200 patients who had indication of contrast neck multi detector computed tomography were included. Calcium volume score of each calcified plaque (density more than 130 HU) was determined by multiplying area of calcified plaque in slice increment and presented as cubic centimeter (cc). Calcium score of each side (right or left) and each patient were determined. Severity of carotid stenosis in axial images was estimated and categorized. Statistical analysis was performed.

RESULTS

87 cases were female with mean age of 58.90 ± 10.67 and 113 cases were male with mean age of 59.61 ± 11.89 years old. The mean of volume score for all evaluated 800 vessels was .079 ± .046 cc. There was no significant difference between calcium score of right and left side (P value = .16). The mean "patient score" was .080 ± .049 cc (range: 0-.15 cc).Nine patients had volume score of 0 and all of them had no evidence of luminal stenosis. Significant increase in severity of stenosis was seen with increase in "patient score".(P value < .001, r = .875).According to receiver operating characteristic analysis, "patient score" of .09 cc with sensitivity of 97% and "patient score" of .12 cc with sensitivity of 95% can predict 50% and 70% stenosis, respectively.

CONCLUSIONS

Promising role of calcium score for predicting severity of carotid stenosis could be considered.

Comparison of Measurement and Grading of Carotid Stenosis with Computed Tomography Angiography and Doppler Ultrasound

BACKGROUND

Doppler ultrasound (DUS) and computed tomography angiography (CTA) are the most commonly used imaging modalities for carotid disease. The aim of this study was to test the accuracy and reproducibility of CTA-derived measurements of carotid stenosis and compare them with those obtained by DUS.

METHODS

Images of 100 carotid arteries of patients who underwent carotid DUS at our unit and CTA of the carotids within a 28-day period were identified retrospectively from multidisciplinary team meeting records. CTAs were assessed by 2 investigators, each using a manual and a semi-automated method. With both methods, the degree of stenosis was calculated using the North American Symptomatic Carotid Endarterectomy Trial equation and graded as mild (0-49%), moderate (50-69%), or severe (70-99%). Cohen's kappa and specificity and sensitivity for ≥50% stenosis were calculated.

RESULTS

The interobserver agreement was moderate (κ 0.407, weighted-κ 0.517) for the manual method and good (κ 0.786, weighted-κ 0.842) for the semi-automated method. Using DUS as the gold standard, the semi-automated method had greater sensitivity (75%) and specificity (91%) in detecting clinically significant carotid artery stenosis (≥50%) than the manual one (63% and 86%, respectively). Agreement between DUS and the semi-automated method of CTA reporting was moderate (κ 0.453, 95% confidence interval [CI]: 0.320-0.586, weighted-κ 0.598, 95% CI: 0.486-0.710), whereas DUS and the manual method of CTA reporting had only fair agreement (κ 0.344, 95% CI: 0.209-0.478, weighted-κ 0.446, 95% CI: 0.315-0.577).

CONCLUSIONS

CTA tends to underestimate the degree of stenosis when compared with DUS. The semi-automated method of CTA reporting has greater reproducibility and greater agreement with DUS. These findings have practical implications when CTA is used to measure the degree of carotid stenosis in clinical practice.

Imaging Interpretation of Temporal Bone Studies in a Patient with Tinnitus: A Systematic Approach

Tinnitus is an auditory perception of internal origin. Tinnitus is not a diagnosis but a symptom with many possible causes and correspondingly divergent pathophysiologic, anatomic, diagnostic, and therapeutic considerations. This article provides a summary of the imaging findings of structural causes of tinnitus.

Color duplex sonography in the detection of internal carotid artery restenosis after carotid endarterectomy: comparison with computed tomographic angiography

OBJECTIVES

Internal carotid artery restenosis after carotid endarterectomy is a major postoperative event, but the clinically best suited means for diagnosis of restenosis are still debated. The objective of this study was to evaluate the sensitivity and specificity of color duplex sonography for detection of substantial internal carotid artery restenosis, verified by computed tomographic (CT) angiography.

METHODS

The study group consisted of 210 consecutive patients with internal carotid artery restenosis, defined as restenosis of 50% or greater, verified by color duplex sonography. The degree of restenosis was calculated according to the European Carotid Surgery Trial guidelines. All patients underwent CT angiography. The specificity, sensitivity, positive predictive value, and negative predictive value of color duplex sonography were calculated.

RESULTS

In 85 patients, internal carotid artery restenosis on color duplex sonography was 50% to 69%, whereas in 125 patients it was 70% or greater. When color duplex sonography was compared with CT angiography, only 2 patients in the group with restenosis of 50% to 69% were misclassified by color duplex sonography, in whom CT angiography showed stenosis of 70% or greater. No patient with stenosis of 70% or greater on color duplex sonography was shown to have a lesser degree of restenosis on CT angiography. When compared with CT angiography, color duplex sonography had specificity of 97.7%, sensitivity of 100%, a positive predictive value of 98.4%, and a negative predictive value of 100% for the detection of internal carotid artery restenosis.

CONCLUSIONS

Color duplex sonography can be effectively used as a primary diagnostic tool for evaluation of patients with suspected internal carotid artery restenosis after carotid endarterectomy.

Concordance rates of Doppler ultrasound and CT angiography in the grading of carotid artery stenosis: a systematic literature review

Physicians have been increasingly relying on noninvasive imaging methods to grade carotid stenosis. The accuracy of Doppler ultrasound (DUS) and CT angiography (CTA) versus intra-arterial angiography (IA) has been assessed in many studies and at least two meta-analyses. Here, we performed a systematic review of studies that compared DUS to CTA. In a PubMed review of the literature from 2000 to 2009, we found 12 studies that compared DUS and CTA-based grading of carotid stenosis. Only 4 of them included at least 20 patients and provided data to classify the diseased arteries into the following categories: mild, moderate or severe NASCET stenosis or occlusion. We extracted 431 arteries from 244 patients (range per study: 48-164). It was not possible to distinguish symptomatic from asymptomatic stenoses. Nearly half arteries had severe stenosis (46% based on DUS and 43% based on CTA). The weighted kappa was 0.85 (95% CI 0.76-0.94), and the accuracy was 0.78. When the arteries were classified into medical and potentially surgical groups, the kappa was 0.76 (95% CI 0.70-0.83), and the accuracy was 0.89. Overall, 17% of the stenoses classified as medical based on DUS were reclassified as surgical based on CTA and 14% of the stenoses classified as medical based on CTA were reclassified as surgical based on DUS. The sparse available data comparing DUS and CTA suggest that the grading of a carotid stenosis as medical or potentially surgical remains uncertain in a relatively high proportion of patients.

Carotid artery occlusive disease and ocular manifestations: Importance of identifying patients at risk

Ocular manifestations of carotid artery occlusive disease, when present, warrant further systemic workup including carotid artery Doppler ultrasound scan. Vascular ocular pathology that may indicate underlying carotid artery disease includes amaurosis fugax, retinal emboli, ocular ischemic syndrome, retinal vascular occlusions, and glaucoma. Early atherosclerotic changes, however, may remain undetected with carotid artery Doppler ultrasound scan. Risk factors for atherosclerosis should be assessed, and additional imaging to detect underlying pathophysiology of carotid artery occlusive disease may also be indicated for preventative management. A review of the literature is conducted to determine the association of ocular sequelae with hemodynamically significant carotid artery stenosis. The role of brachial artery flow-mediated dilation as an independent predictor for cardiovascular disease is also discussed.

In vivo Doppler ultrasound quantification of turbulence intensity using a high-pass frequency filter method

The objective of this investigation was to implement a high-pass frequency filter method to analyze Doppler ultrasound velocity waveforms and quantify turbulence intensity (TI) in vivo. Doppler velocity data were analyzed using two techniques, based on either ensemble averaging or high-pass frequency domain filtering of the periodic waveforms. The accuracy and precision of TI measurements were determined with controlled in vitro experiments, using a pulsatile-flow model of a stenosed carotid bifurcation. The high-pass filter technique was also applied in vivo to determine whether this technique could successfully distinguish between pertinent hemodynamic sites within the carotid artery bifurcation. Twenty-five seconds of Doppler audio data were acquired at three sites (common carotid artery [CCA], internal carotid artery [ICA] stenosis and distal ICA) within 10 human carotid arteries, and repeated three times. Doppler velocity data were analyzed using a ninth-order high-pass Butterworth filter with a 12-Hz inflection point. TI measured within the CCA and distal ICA was found to be significantly different (p < 0.0001) for moderate to nearly occluded carotid artery classifications. Also, TI measured within the distal ICA increased with stenosis severity, with the ability to distinguish between each stenosis class (p < 0.05). This investigation demonstrated the ability to precisely quantify TI using a conventional Doppler ultrasound machine in human subjects, without interfering with normal clinical protocols.

Imaging in endovascular therapy: our future

The endovascular therapist now has many modern imaging techniques available to plan and execute treatment, whereas in the past vascular surgeons relied mostly on clinical examination and arteriography. Advances in computer technology have enabled fast acquisition and processing of the large amounts of digital data essential to capture the dynamic information from fast-flowing blood at high resolution. Functional imaging has begun to play a role in predicting stability of progressive vascular disease and the need for and risks of intervention. Computing power now affords the interventionist the ability to handle imaging data in powerful 3-dimensional programs and electronically "in-lay" a variety of devices to plan complex endovascular procedures from the familiar platform of a laptop. In four major clinical areas, carotid intervention, peripheral intervention, endoluminal grafting, and cardiac imaging, we review the latest advances and changes with an eye toward how we should best be using imaging in our patients undergoing endovascular treatment...now and into the future.

In vitro Doppler ultrasound investigation of turbulence intensity in pulsatile flow with simulated cardiac variability

An in vitro investigation of turbulence intensity (TI) associated with a severe carotid stenosis in the presence of physiological cardiac variability is described. The objective of this investigation was to determine if fluctuations due to turbulence could be quantified with conventional Doppler ultrasound (DUS) in the presence of normal physiological cycle-to-cycle cardiac variability. An anthropomorphic model of a 70% stenosed carotid bifurcation was used in combination with a programmable flow pump to generate pulsatile flow with a mean flow rate of 6 mL/s. Utilizing the pump, we studied normal, nonrepetitive cycle-to-cycle cardiac variability (+/-3.9%) in flow, as well as waveform shapes with standard deviations equal to 0, 2 and 3 times the normal variation. Eighty cardiac cycles of Doppler data were acquired at two regions within the model, representing either laminar or turbulent flow; each measurement was repeated six times. Turbulence intensity values were found to be 11 times higher (p < 0.001), on average, in the turbulent region than in the laminar region, with a mean difference of 24 cm/s. Twenty cardiac cycles were required for confidence in TI values. In conclusion, these results indicate that it is possible to quantify TI in vitro, even in the presence of normal and exaggerated cycle-to-cycle cardiac variability.