Thank you for your answer.

I've tried the solutions of the other thread you've pointed, but still doesn't work.

But I could find something interesting :

As I explained, I copied-pasted text and images from Dreamweaver to MS Word, and I found that if I remove the original images, they don't appear anymore in MS Word.

So it's like Word was keeping the links to thoses images, instead of having really copied the images.

Do you have an idea or do I need to insert again all pictures of the 115 pages ?

Here you can find a sample of my document if needed :
My file