Performance of Carotid Ultrasound in Evaluating Candidates for Carotid Endarterectomy Is Optimized by an Approach Based on Clinical Outcome Rather Than Accuracy

Jl, Wilterdink; Feldmann, Edward; Jd, Easton; Ward, Roxanne

doi:10.1161/01.str.27.6.1094

Cited by 25 publications

(7 citation statements)

References 20 publications

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“…12,31 Therefore, additional tests are required in order to refrain from carotid endarterectomy in patients who do not meet the criteria. These tests should be based preferably on linear lumen reduction measurements.…”

Section: Dmentioning

confidence: 99%

Lumen reduction measurements of the internal carotid artery before and after Levovist enhancement: reproducibility and agreement with angiography.

Elgersma

Leeuwen

Meijer

et al. 1999

Journal of Ultrasound in Medicine

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Our aim was to assess reproducibility of three different lumen reduction measuring methods‐‐North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial, and common carotid‐‐using power Doppler and color Doppler sonography before and after Levovist enhancement. We included 20 symptomatic patients with mild or severe carotid disease. North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial, and common carotid measurements on longitudinal views and European Carotid Surgery Trial measurements on transverse views were performed. Examinations were repeated and the results compared to assess reproducibility of measurements. Correlation with angiography was obtained by calculating Pearson correlation coefficients. Reproducibility was significantly better (P < 0.05) for European Carotid Surgery Trial and common carotid measurements (95% limits of agreement between ‐10% to 10% and ‐19% to 17%) as compared to North American Symptomatic Carotid Endarterectomy Trial measurements (95% limits of agreement between ‐11% to 21% and ‐21% to 23%). Variability of measurements after enhancement increased slightly (not significant) for both power and color Doppler sonography. Additionally, European Carotid Surgery Trial measurements, using nonenhanced power Doppler or color Doppler sonography, did not correlate significantly with angiography, whereas North American Symptomatic Carotid Endarterectomy Trial and common carotid measurements correlated well with angiography, particularly in power Doppler mode after enhancement (r = 0.88 and r = 0.82, respectively). We conclude that for lumen reduction measurements of the internal carotid artery with power and color Doppler sonography, the common carotid method is the only method that is reproducible and has good correlation with angiography, which slightly improves after Levovist enhancement.

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Section: Dmentioning

confidence: 99%

Lumen reduction measurements of the internal carotid artery before and after Levovist enhancement: reproducibility and agreement with angiography.

Elgersma

Leeuwen

Meijer

et al. 1999

Journal of Ultrasound in Medicine

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“…There has been extensive research into determining the sources of errors in peak velocity measurement. Clinical Doppler studies have focussed on determining how velocity and other criteria 1,[3][4][5][6] affect the accuracy of diagnostic evaluation. Previous studies of technologist variability in the measurement of peak systolic velocity on patients showed significant variability.…”

mentioning

confidence: 99%

Human factors as a source of error in peak Doppler velocity measurement

Lui

Steinman

Cobbold

et al. 2005

Journal of Vascular Surgery

123

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Doppler ultrasound peak velocity measurements are widely used for the diagnostic assessment of the severity of arterial stenoses. However, it is known that these measurements are often in error. We have identified subjective human factors introduced by the technologist and assessed their contribution to peak velocity measurement error and variability. It is to be hoped that by understanding this, improvements in the machine design and measurement methods can be made that will result in improved measurement accuracy and reproducibility.

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“…Because we used duplex as a screening tool for carotid disease, the threshold value was optimized by maximizing sensitivity while maintaining high test accuracy for both periods independently. 18 In addition, logistic regression analysis was used in both periods to assess whether combining the various hemodynamic parameters and ratios would increase duplex performance (ie, increase the AUC). Models were fit with various combinations of single parameters and ratios to estimate regression coefficients.…”

mentioning

confidence: 99%

Changes Over Time in Optimal Duplex Threshold for the Identification of Patients Eligible for Carotid Endarterectomy

Elgersma

Leersum

Buijs

et al. 1998

Stroke

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Background and Purpose-Two surgical trials established that carotid endarterectomy is beneficial to symptomatic patients who have a severe internal carotid artery (ICA) stenosis on angiograms. Duplex ultrasonography-derived hemodynamic parameters show a good correlation with angiography and are often used for detecting severe ICA stenoses. However, duplex performance is ultrasound machine and operator dependent. Over time both may change, possibly affecting duplex performance. We compared duplex performance of 2 time periods in 1 specific vascular laboratory using angiography as the gold standard. Methods-Consecutive patients who underwent both angiography and duplex examinations of the ICA were evaluated (first period, 60 patients; second period, 61 patients). Peak systolic velocity and several other hemodynamic parameters and ratios were analyzed by receiver operating characteristic curves in their ability to detect severe ICA stenoses. The optimal parameter and threshold were determined for each period. Subsequently, duplex test characteristics were compared after the optimal thresholds of both the first and the second periods were applied in the second period. Results-In both periods peak systolic velocity of the ICA was the best test parameter; areas under the receiver operating characteristic curve were similar (0.957 and 0.954, respectively). However, the optimal threshold was different. The optimal threshold in the second period was 270 cm/s. When the optimal threshold of 210 cm/s of the first period was applied in the second period, test characteristics changed significantly. Sensitivity increased from 98% to 100%, and specificity decreased from 85% to 71% (Pϭ0.004). Conclusions-The optimal threshold for detecting severe ICA stenoses with duplex ultrasonography in our laboratory changed over time. Individual laboratories should assess duplex accuracy regularly and adjust adopted criteria if necessary to keep diagnostic performance optimal.

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Performance of Carotid Ultrasound in Evaluating Candidates for Carotid Endarterectomy Is Optimized by an Approach Based on Clinical Outcome Rather Than Accuracy

Abstract: The use of ROC analysis and available outcome data can improve the performance of CDUS in selecting endarterectomy candidates for cerebral angiography.

Cited by 25 publications

References 20 publications

Lumen reduction measurements of the internal carotid artery before and after Levovist enhancement: reproducibility and agreement with angiography.

Lumen reduction measurements of the internal carotid artery before and after Levovist enhancement: reproducibility and agreement with angiography.

Human factors as a source of error in peak Doppler velocity measurement

Changes Over Time in Optimal Duplex Threshold for the Identification of Patients Eligible for Carotid Endarterectomy

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