Grading carotid stenosis with ultrasound: An interlaboratory comparison

Andrei Alexandrov, Doralene Vital, Dianne S. Brodie, Paul Hamilton, James C. Grotta

Research output: Contribution to journalArticle

70 Citations (Scopus)

Abstract

Background and Purpose: Carotid ultrasound had modest accuracy in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) of carotid endarterectomy in predicting severe carotid stenosis when a 250-cm/s peak systolic velocity (PSV) criterion was applied to different laboratories. We compared the performance of two independent laboratories using similar equipment (ATL-HDI Ultramark 9) but different interpretation criteria. Methods: Consecutive patients who underwent both color-coded duplex ultrasound and intra-arterial digital subtraction angiography were studied. PSV was determined with angle correction at the site of the tightest arterial narrowing. Carotid stenosis was measured on angiograms using the North american (N) method. Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values with 95% confidence intervals were calculated for each laboratory. Results: In 87 patients, 174 bifurcations were imaged. A 250-cm/s criterion was the best single predictor of a >70% N stenosis at one laboratory (sensitivity 93%, [95% confidence interval, 85 to 101], specificity 86% [76 to 96], PPV 75% [62 to 87], and NPV 96% [90 to 102]) but had modest parameters at the other laboratory (50% [34 to 64], 87%, [77 to 97], 60 [44 to 76], and 91 [82 to 100], respectively). However, the diagnostic criteria routinely used in the second laboratory included different velocity values, which when applied decreased specificity by 17% but increased sensitivity by 35% (85% [74 to 96], 70% [56 to 84], 90% [81 to 99], and 77% of [64 to 90], respectively. Conclusions: Despite the use of similar equipment, ultrasound grading of carotid stenosis is operator dependent and relies on different and individually validated criteria. Greater sensitivity of ultrasound screening is achieved by applying diagnostic criteria specific to each laboratory. Multicenter studies should use laboratory-specific criteria and a local validation process.

Original languageEnglish (US)
Pages (from-to)1208-1210
Number of pages3
JournalStroke
Volume28
Issue number6
DOIs
StatePublished - Jan 1 1997

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Carotid Stenosis
Carotid Endarterectomy
Confidence Intervals
Equipment and Supplies
Digital Subtraction Angiography
Multicenter Studies
Angiography
Pathologic Constriction
Color
Sensitivity and Specificity

All Science Journal Classification (ASJC) codes

  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine
  • Advanced and Specialized Nursing

Cite this

Alexandrov, A., Vital, D., Brodie, D. S., Hamilton, P., & Grotta, J. C. (1997). Grading carotid stenosis with ultrasound: An interlaboratory comparison. Stroke, 28(6), 1208-1210. https://doi.org/10.1161/01.STR.28.6.1208

Grading carotid stenosis with ultrasound : An interlaboratory comparison. / Alexandrov, Andrei; Vital, Doralene; Brodie, Dianne S.; Hamilton, Paul; Grotta, James C.

In: Stroke, Vol. 28, No. 6, 01.01.1997, p. 1208-1210.

Research output: Contribution to journalArticle

Alexandrov, A, Vital, D, Brodie, DS, Hamilton, P & Grotta, JC 1997, 'Grading carotid stenosis with ultrasound: An interlaboratory comparison', Stroke, vol. 28, no. 6, pp. 1208-1210. https://doi.org/10.1161/01.STR.28.6.1208
Alexandrov, Andrei ; Vital, Doralene ; Brodie, Dianne S. ; Hamilton, Paul ; Grotta, James C. / Grading carotid stenosis with ultrasound : An interlaboratory comparison. In: Stroke. 1997 ; Vol. 28, No. 6. pp. 1208-1210.
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abstract = "Background and Purpose: Carotid ultrasound had modest accuracy in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) of carotid endarterectomy in predicting severe carotid stenosis when a 250-cm/s peak systolic velocity (PSV) criterion was applied to different laboratories. We compared the performance of two independent laboratories using similar equipment (ATL-HDI Ultramark 9) but different interpretation criteria. Methods: Consecutive patients who underwent both color-coded duplex ultrasound and intra-arterial digital subtraction angiography were studied. PSV was determined with angle correction at the site of the tightest arterial narrowing. Carotid stenosis was measured on angiograms using the North american (N) method. Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values with 95{\%} confidence intervals were calculated for each laboratory. Results: In 87 patients, 174 bifurcations were imaged. A 250-cm/s criterion was the best single predictor of a >70{\%} N stenosis at one laboratory (sensitivity 93{\%}, [95{\%} confidence interval, 85 to 101], specificity 86{\%} [76 to 96], PPV 75{\%} [62 to 87], and NPV 96{\%} [90 to 102]) but had modest parameters at the other laboratory (50{\%} [34 to 64], 87{\%}, [77 to 97], 60 [44 to 76], and 91 [82 to 100], respectively). However, the diagnostic criteria routinely used in the second laboratory included different velocity values, which when applied decreased specificity by 17{\%} but increased sensitivity by 35{\%} (85{\%} [74 to 96], 70{\%} [56 to 84], 90{\%} [81 to 99], and 77{\%} of [64 to 90], respectively. Conclusions: Despite the use of similar equipment, ultrasound grading of carotid stenosis is operator dependent and relies on different and individually validated criteria. Greater sensitivity of ultrasound screening is achieved by applying diagnostic criteria specific to each laboratory. Multicenter studies should use laboratory-specific criteria and a local validation process.",
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