How to read an SVG with a given size using PHP Imagick?

I have the following code:

$image = new Imagick();

$image->setBackgroundColor(new ImagickPixel('green'));

$image->setSize(20,20);

$image->readImageBlob(file_get_contents('./some/path/image.svg'));

It loads the SVG just fine but the setSize just gets completely ignored. It renders at 550x100, as per it's definition:

<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" 

    xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"

    width="550px" height="100px" viewBox="0 0 550 100" 

    enable-background="new 0 0 550 100" xml:space="preserve">

Has anyone got experience in getting SVG files to play nice with setSize ?