prueba asi
Código PHP:
<?php foreach ($todos as $c=>$articulo) { ?>
<th scope="row"><?php
if ($articulo['ct']!=0){
echo nl2br($articulo['ct']);
?></th>
<th scope="row"><?php echo $articulo ['ds'];?><br></th>
<td><?php echo $articulo ['pe'];?><br></td>
<td><?php echo $articulo ['to'];?><br></td>
<?php }
?></th>
<?php } ?>
saludos