A myelogram consists of a series of plain xrays with different views (front, side, oblique) with a contrast agent already injected into the spinal fluid filled sac surrounding the nerves and/or spinal cord. This test demonstrates the flow of contrast in the fluid and reveals if there is obstruction to the flow. The C.A.T. scan that usually follows the myelogram depicts this same anatomy from a C.A.T. scan perspective. Each test has a particular advantage and the combined tests produce a more comprehensive analysis than either test alone. Therefore, a single injection of contrast into the spinal fluid sac is used for both tests. This test is usually done by to view a specific anatomic region: cervical, thoracic, lumbar. Occasionally, a complete myelogram and C.A.T. scan would be performed involving a single injection of contrast and them xrays taken of all regions of the spine (cervical, thoracic, lumbar) followed by the C.A.T. scan of all of those same regions.