To make it simple, no. Do not include images when you send bulk email. Images can be regarded as spam keys and can send the email straight to the spam box. If it's a necessity to include an image in the email, make sure the the text to image ratio does not exceed 60:40. Never exceed more than 40% images over text in the email.
Creating an HTML image with text in the image does not make the email partially text. The email will have a more likely chance of hitting the junk box. You must always remember, that sending to 3rd party lists is prospecting for new clients.
You do not want your email blast to look like an ad. Recipients will see it as an ad and not even think twice about about it as they delete it. Stay simple, short, and to the point.
Think about yourself receiving two different emails; one that looks like an ad and one that is a short message. Which one would you click through on?