<?php
class Res {
   public $id;
   public $pagetitle;

   public function info()
   {
      return '#'.$this->id.': '.$this->pagetitle;
   }
}

$query = "SELECT id,pagetitle FROM modx_site_content LIMIT 10";

$result = $modx->prepare($query);
$result->setFetchMode(PDO::FETCH_CLASS, 'Res');
$result->execute();
while ($res = $result->fetch()) {
    echo $res->info().'<br />'."\n";
}