Reply:
======

* Eric S. Bartlett
* Thomas D. Walters
* Sean P. Symons
* Allan J. Fox

We thank Dr. Friedman for the interest in our recent article regarding quantification of carotid stenosis on CT angiography.1 It is correct that the original data were not evaluated according to gender. We realized this oversight after publication of the original article.

We are currently undertaking a rigorous reanalysis of the data to incorporate gender into the model. By using gender-specific receiver operating characteristic curves, our preliminary data have shown that there is indeed a difference in the ideal cutoff values for severe and moderate disease in men and women. The difference, however, is only 0.1 mm, which makes the severe cut-off value for women 1.2 mm and the moderate cutoff value 2.1 mm. We are working to determine the statistical significance of this subtle difference. Because female patients comprised only 31% (42/132) of the original data, analysis of additional female patients may be necessary to have adequate power to examine this relationship.

In summary, our preliminary reanalysis has shown a slight difference in the gender cutoff values for severe and moderate carotid stenosis in CTA quantification. The difference, however, is very subtle, at 0.1 mm, which could be considered within range of acceptable measurement error for any given carotid. We hope to provide a more thorough statistical analysis of the gender differences in the near future.

## Reference

1.  Bartlett ES, Walters TD, Symons SP, et al. **Quantification of carotid stenosis on CT angiography.** AJNR Am J Neuroradiol 2006;27:13–9
    
    [Abstract/FREE Full Text](http://www.ajnr.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiYWpuciI7czo1OiJyZXNpZCI7czo3OiIyNy8xLzEzIjtzOjQ6ImF0b20iO3M6MjI6Ii9ham5yLzI3LzgvMTYwMS4yLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

*   Copyright © American Society of Neuroradiology