X-rays. These can check for bone problems caused by past injury, arthritis, recently broken or dislocated bones, or tumors. X-rays aren't used to diagnose carpal tunnel syndrome. But they can be helpful for finding signs of arthritis or an old or new wrist or neck injury that may be adding to your symptoms.
Ultrasound, to look at the size of the median nerve. It is inexpensive, comfortable, and quick. But its use for carpal tunnel syndrome diagnosis is still unproven and fairly uncommon.
MRI. This imaging test can find swelling of the median nerve, narrowing of the carpal tunnel, or problems with circulation of blood through the carpal tunnel.