Create a Magnified Cutaway Detail View in Photoshop

Zoom back to 100% and give your image a final check. Adjust your connector lines if they look off. Add text if desired. Go to Image > Trim to auto-crop the finished image. Drop in a solid colored background as the bottom layer, if desired. Here's a look at the final image along with the layers palette for reference.

If you want to keep the image editable, save it in the native Photoshop PSD format. If your brochure is in another Adobe application, you can place the Photoshop file directly in your layout. Otherwise, you can select all and use the Copy Merged command for pasting into the brochure document, or flatten layers and save a copy to import into your brochure.