How to link image in the slide to a node?

To link the image in the slide to the node you can use the l() function like below:

l($text, $path, $options = array())

if ($vars['imgcache_slide'] <> '<none>' && module_exists('imagecache') &&  is_array(imagecache_presets())){
  $slider_items[$key1]['slide_image'] = 
  l(theme('imagecache', 
          $vars['imgcache_slide'], 
          $filepath,
          check_plain($result->node_title)),                  
    'node/' . $result->nid,
    array('html' => TRUE,) // needed, Whether the title is HTML, or just plain-text. TRUE for HTML
  );
}
else {          
  $slider_items[$key1]['slide_image'] = 
  l('<img src="' . base_path() . $filepath . '" alt="' . check_plain($result->node_title) . '"/>',                  
    'node/' . $result->nid,
    array('html' => TRUE,) // needed, Whether the title is HTML, or just plain-text. TRUE for HTML
  );
}