Once the clinical diagnosis "myelopathy" is established, the underlying cause must be investigated. Most commonly this involves medical imaging. The best way to visualize the spinal cord is magnetic resonance imaging (MRI). Apart from T1 and T2 MRI images, which are commonly used for routine diagnosis, more recently researchers are exploring quantitative MRI signals. Further imaging modalities used for evaluating myelopathy include plain X-rays for detecting arthritic changes of the bones, and Computer Tomography, which is often used for pre-operative planning of surgical interventions for cervical spondylotic myelopathy. Angiography is used to examine blood vessels in suspected cases of vascular myelopathy.