When making an image map, you can choose to break it apart instead of coding the edges. Use the guides to represent the edge of each area on your map. Go to View and make sure Lock to Guides is checked. Use the square Selection Tool on the different areas. Copy and paste each to its new document. Save them as separate files. Placing the images on the page put them in a table (or center them if that will work) according to the image shape.

When you scan images, they're not always exactly straight on the scanner. You don't want to cut out parts of the image like this: