Remove WordPress featured image from attached images

I Recently worked on a project where we setup a custom post type for a client’s portfolio items. The main portfolio page had a grid of the featured images for each project and would allow the user to click through to view the portfolio item. When you landed on the portfolio item, all images that were attached to the post were displayed using the jquery cycle plugin.

Problem is the featured image is part of these group of images because it is attached.

Here is how we displayed the images and removed the featured image.

      <?php
          $thumb_ID = get_post_thumbnail_id( $post->ID );
          if ( $images = get_children(array(
                  'post_parent' => get_the_ID(),
                  'post_type' => 'attachment',
                  'post_mime_type' => 'image',
                  'order' => ASC,
                  'orderby' => menu_order,
                  'exclude' => $thumb_ID
              ))) : ?>

              <?php foreach( $images as $image ) :  ?>
                  <div><?php echo wp_get_attachment_link($image->ID, 'portfolio_image'); ?></div>
              <?php endforeach; ?>

      <?php else: ?>
        Nothing added yet
      <?php endif; ?>