tedster - 5:16 pm on May 1, 2011 (gmt 0)
Does your CMS require you to include the "/myArticleWithoutImage1/" segment in the path to the image file?
If it does, then I think TheMadScientist made a good suggestion. If it doesn't (or if the CMS can be modified) then you can always use the same file path to the "No Image Available" image.
But most of all - I don't think this is an issue. Are you seeing something in your traffic or rankings that makes you think it is an issue?