A lumbar CT myelogram is a test that is done to find a tumor, infection or spinal problem such as a herniated disk, according to WebMD. A contrast dye is put into the fluid-filled space between the bones in the spine, along with X-rays and a CT scan.
During a myelogram test, the contrast dye is injected into the subarachnoid space with a thin needle, according to WebMD. Before the needle is inserted into the spinal area, the patient is given numbing medication. The dye is important because it allows health care professionals to see the nerves and spinal cord more clearly. In some cases, an X-ray or CT scan may be done both before and after the dye is used. Normally, a CT scan is done after X-rays are taken to gather the most information possible.
Sometimes a myelogram and lumbar CT test are done to find causes of extremity weakness, pain or numbness, states WebMD. Narrowing of the spine may also be found using this test. Inflammation of the membrane that covers the spine and brain is also detected with this procedure. While a CT scan and MRI are useful tests on their own, a myelogram often shows causes of pain that cannot be seen without the use of the contrast dye.