Yep! While X-rays are excellent at showing bones, they are bad at showing anything else.
An MRI can show not only the bone but bleeding, swelling and fluid within the bone. The detail is amazing. Imaged below to the left is a MRI view of a knee joint. The red circle reveals a stress reaction or pre-stress fracture of a tibia. You can clearly see the white area which represents bleeding or fluid within the tibial bone.
This next image is an x-ray of the same knee. Nowhere on the image can you see the stress reaction or pre-stress fracture. The yellow circle represents the area where the stress reaction is located and is identified by the corresponding MRI scan.
When people come to the office with pain in the region of the bone and the plain x-rays are normal, our next imaging study ordered is a MRI. Very rarely will I ever see a patient with a stress fracture that is present on a plain x-ray.