Diagnosis of Shoulder Tendonitis
In addition to a complete medical history and physical exam, diagnostic procedures for shoulder tendonitis may include:

X-ray. Invisible electromagnetic energy beams produce images of internal tissues, bones, and organs onto film.

Magnetic resonance imaging, or MRI. Large magnets and a computer produce detailed images of organs and structures within your body.

Ultrasonography. High frequency sound waves create an image of some part of the inside of your body.