Not sure. I imagine they'd rely mainly on x-rays to make a diagnosis, since many of the symptoms are similar to other pulmonary issues like asthma and COPD and lung capacity tests (blowing into this little gadget that measures the force of your breath) only tell you whether there's a breathing problem--not what's actually causing it. Sometimes x-rays can be ambiguous and require additional imaging and/or other "interpretations" of the same image. The process of diagnosing can be tough, unfortunately. I wish I had a more encouraging answer. Best thing to do is get it checked out as soon as you can, since most treatments work better the earlier you start.