Pneumatic robot arranges limbs for MRI 'sweet spot'

A pneumatic robot that positions patients' limbs inside an MRI scanner allows physicians to exploit a bizarre phenomenon where hard-to-see tendons jump into sharp focus when held at the right angle. That "magic angle" effect happens when a tendon is at 55 to a scanner's powerful magnetic field and can help with diagnosing tendon injuries. Nuclei are pinged with radio waves to momentarily shove them out of the field's grip, and they emit their own radio waves as they settle back into place. Those signals reveal their position and are translated into a 3D image. Different tissues can be identified because the density of hydrogen nuclei varies from one to the other.