In API 1.0, we can use users/profile_image/:screen_name
For example : http://api.twitter.com/1/users/profile_image/EA_FIFA_FRANCE
B
Hare is a very simple way to get Twitter Profile picture.
http://res.cloudinary.com/demo/image/twitter_name/w_300/{User_Name}.jpg
it's my Profile picutre: Big: http://res.cloudinary.com/demo/image/twitter_name/w_300/avto_key.jpg
Small: http://res.cloudinary.com/demo/image/twitter_name/w_100/avto_key.jpg
you can regulate size by this part of URL - w_100, w_200, w_500 and etc.