Acoustic shadowing impairs accurate characterization of stenosis in carotid ultrasound examinations

Mohebali, Jahan; Patel, Virendra I.; Romero, Javier; Hannon, Kathleen; Jaff, Michael R.; Cambria, Richard P.; LaMuraglia, Glenn M.

doi:10.1016/j.jvs.2015.06.137

Cited by 19 publications

(13 citation statements)

References 37 publications

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“…The reduced dependency of flow alignment and the use of more flow data are an advantage when stenoses are calcified creating acoustic shadowing. A previous study of carotid artery stenosis showed that in the presence of calcifications, spectral Doppler US is inadequate to accurately determine the degree of stenosis when compared with computed tomographic angiography 35 . According to Table 2 , 50% of the included patients in this study had shadowing calcifications in the SFA stenosis, and vector concentration still correlated well with the corresponding stenosis degree percentage.…”

Section: Discussionmentioning

confidence: 99%

Vector Flow Imaging Compared with Digital Subtraction Angiography for Stenosis Assessment in the Superficial Femoral Artery – A Study of Vector Concentration, Velocity Ratio and Stenosis Degree Percentage

Hansen

Ewertsen

et al. 2019

Ultrasound Int Open

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Stenosis of the superficial femoral artery (SFA) induces complex blood flow with increased velocities. Disease assessment is performed with Doppler ultrasound and digital subtraction angiography (DSA), but Doppler ultrasound is limited by angle dependency and DSA by ionizing radiation. An alternative is the vector flow imaging method based on transverse oscillation (TO), an angle-independent vector velocity technique using ultrasound. In this study, flow complexity and velocity measured with TO were compared with DSA for the assessment of stenosis in the SFA.The vector concentration, a measure of flow complexity, and the velocity ratio obtained from the stenosis and a disease-free adjacent vessel segment, were estimated with TO in 11 patients with a total of 16 stenoses of the SFA. TO data were compared with the corresponding stenosis degree percentage obtained with DSA.The correlation between the vector concentration and DSA was very strong (R=0.93; p<0.001; 95% confidence interval (CI): 0.81–0.98), while only moderate for velocity ratio and DSA (R=0.50; p<0.07; 95% CI: 0.00–0.80). The correlation coefficients that were found were significantly different (p<0.005) without overlapping CI.The study indicated that flow changes in the SFA induced by stenosis can be quantified with TO, and that stenosis grading may be improved by estimation of flow complexity instead of velocity ratio. TO is a potential diagnostic tool for the assessment of atherosclerosis and peripheral arterial disease.

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Section: Discussionmentioning

confidence: 99%

Vector Flow Imaging Compared with Digital Subtraction Angiography for Stenosis Assessment in the Superficial Femoral Artery – A Study of Vector Concentration, Velocity Ratio and Stenosis Degree Percentage

Hansen

Ewertsen

et al. 2019

Ultrasound Int Open

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“…This, potentially hinders accurate flow readings within the stenotic region. A recent publication showed that, in the presence of AS, CDUS alone appears to be inadequate to accurately determine the degree of carotid stenosis, and to identify patients with severe disease [13]. This study had several limitations as stated by its authors –Only 17% of lesions with AS had a concomitant CTA, which could introduce a selection bias.…”

Section: Discussionmentioning

confidence: 97%

“…In addition, the gold standard used was CTA cross-sectional area reduction. The amount of flow through a lumen is indeed proportional to its cross-sectional area, but seen as atherosclerotic residual lumens are irregular in shape this method might be less accurate to consider as gold standard and presents further bias [13].…”

Section: Discussionmentioning

confidence: 99%

“…This results in reduced sensitivity and specificity and, possibly, loss of reliability. A recent publication has shown that in the presence of AS, CDUS alone appears to be inadequate to accurately determine the degree of carotid stenosis and to identify patients with severe disease, but did not specify the differential effect of AS size on test reliability [13]. Currently, there is no consensus in the literature on how to grade the extent of AS since it is highly variable and dependent on plaque quality, localization and size.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of carotid artery ultrasonography in the presence of an acoustic shadow artifact

Seyman

Bornstein²,

Auriel

et al. 2019

BMC Neurol

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Background B-mode and Color Doppler ultrasonography (CDUS) are the methods of choice for screening and determining the degree of Carotid artery stenosis. The evaluation of stenosis with calcification may be hampered by a common CDUS artifact known as acoustic shadow (AS). Our objective was to assess the change in reliability of CDUS readings in the presence of an AS artifact. Methods Single center retrospective observational study. Included were patients with either an AS artifact or high-grade stenosis (defined by peak systolic velocity (PSV) > 240 cm/s) demonstrated in CDUS, and had a CT angiography (CTA) done within 6 months of the sonographic exam. All subjects were identified through the Tel-Aviv Sorasky medical center (TASMC) CDUS unit registry from which clinical information was extracted. CDUS images were manually reviewed grading AS magnitude. All CTAs were reviewed and reconstructed for accurate assessment of percent stenosis and were used as gold standard. Results The study cohort included 227 consecutive patients (corresponding with 454 internal carotid arteries) meeting inclusion criteria. 43.2% of the arteries ( n = 195) had an AS artifact present on CDUS, regardless of percent stenosis, with a large artifact present in 6.7% arteries ( n = 30). Older age was significantly related to the presence of AS artifact ( p < 0.001). In the study cohort as a whole there was a strong correlation between percent stenosis on CTA and PSV values (Pearson’s r 0.672, p < 0.001) regardless of AS existence. The CDUS sensitivity and specificity for predicting severe stenosis were 82 and 73% respectively. The presence of a small AS slightly diminished the correlation between CDUS and CTA results without compromising CDUS reliability. A large AS severely affected the correlation between CDUS and CTA exams (Pearson’s r = 0.24, p = 0.27) and reduced CDUS reliability with a sensitivity and specificity of 62%. Conclusion The presence of a large AS severely degrades the accuracy of the routine CDUS measurements. In these cases, the patient should be referred to a CDUS exam including doppler-measurement of periorbital arteries and intracranial arteries in addition to other imaging modalities such as CTA or MRA in order to assess future stroke risk.

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“…The presence of calcified plaques is common for carotid artery stenosis patients and results in acoustic shadowing. This obscures the DUS's ability to obtain valid velocity estimates with a reported low sensitivity ranging from 22.7% to 32.5% [35]. Since all flow data within the ROI are used for flow estimation, VC is not dependent on flow alignment meaning that the VC estimate is less affected by acoustic shadowing [36].…”

Section: Discussionmentioning

confidence: 99%

Carotid Stenosis Assessment with Vector Concentration before and after Stenting

Brandt¹,

Nguyen²,

Gutte³

et al. 2020

Diagnostics

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Digital subtraction angiography (DSA) is considered the reference method for the assessment of carotid artery stenosis; however, the procedure is invasive and accompanied by ionizing radiation. Velocity estimation with duplex ultrasound (DUS) is widely used for carotid artery stenosis assessment since no radiation or intravenous contrast is required; however, the method is angle-dependent. Vector concentration (VC) is a parameter for flow complexity assessment derived from the angle independent ultrasound method vector flow imaging (VFI), and VC has shown to correlate strongly with stenosis degree. The aim of this study was to compare VC estimates and DUS estimated peak-systolic (PSV) and end-diastolic velocities (EDV) for carotid artery stenosis patients, with the stenosis degree obtained with DSA. Eleven patients with symptomatic carotid artery stenosis were examined with DUS, VFI, and DSA before and after stent treatment. Compared to DSA, VC showed a strong correlation (r = −0.79, p < 0.001), while PSV (r = 0.68, p = 0.002) and EDV (r = 0.51, p = 0.048) obtained with DUS showed a moderate correlation. VFI using VC calculations may be a useful ultrasound method for carotid artery stenosis and stent patency assessment.

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Acoustic shadowing impairs accurate characterization of stenosis in carotid ultrasound examinations

Cited by 19 publications

References 37 publications

Vector Flow Imaging Compared with Digital Subtraction Angiography for Stenosis Assessment in the Superficial Femoral Artery – A Study of Vector Concentration, Velocity Ratio and Stenosis Degree Percentage

Vector Flow Imaging Compared with Digital Subtraction Angiography for Stenosis Assessment in the Superficial Femoral Artery – A Study of Vector Concentration, Velocity Ratio and Stenosis Degree Percentage

Assessment of carotid artery ultrasonography in the presence of an acoustic shadow artifact

Carotid Stenosis Assessment with Vector Concentration before and after Stenting

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