title: PyDICOM can't read pixel data and needs GDCM or Pillow
body: <p>I'm using <code>pydicom</code> and my code is pretty straightforward:</p>
  
  <pre><code>image = np.stack([s.pixel_array for s in scans])
  </code></pre>
  
  <p>But this gives a runtime error:</p>
  
  <pre><code>RuntimeError: The following handlers are available to decode the pixel data however they are missing required dependencies: GDCM (req. GDCM), Pillow (req. Pillow)
  </code></pre>
  
  <p>I'm not sure what to do. Any help would be.. helpful.</p>