X-rays provide excellent detail of bones because they consists mainly of minerals which block xray beams. However, soft tissue such as discs and nerve roots do not have such minerals, so an x-ray does not capture an image of these structures. Therefore, xrays are not useful for the diagnosis of disc herniations. They give useful information about the alignment of the spine. Many different angles of xrays may be necessary to fully diagnose a disorder including but not limited to AP, Lateral, Flexion, extension or scoliosis views.
The most useful imaging study available for the diagnosis of the majority of brain, spine, and spinal cord problem. MRI scans provide highly detailed images of non bony anatomy.
No radiation is used to perform an MRI scan, and they may safely be done on pregnant women. However, patients with certain implants such as a pacemaker, spinal stimulator should not have an MRI scan because the magnetic field will cause the device to malfunction.
A CT scan is a highly detailed x-ray that can provide images of the body in different views. Like an x-ray, a CT scan works by shooting an x-ray beam through the body. Next, a computer is used to reformat the image into cross sections of the spine. Like xrays, they provide excellent bony detail, and are useful for evaluating fractures and other bony lesions. They do provide useful information about some soft tissue lesions, such as very dense tumors.
A myelogram consists obtaining xrays of a region of the spine after injecting a radiographically opaque dye (dye that can be seen on x-rays) into the sac around the nerve roots. When combined with a myelogram, a CT scan provides for excellent nerve detail. The myelogram adds additional risk to the CT scan( such as a spinal headache) but provides substantial information about the spinal cord, spinal canal and nerve roots as well as any lesions that may narrow the spinal canal. First the myelogram is performed by a radiologist then the CT scan is obtained.
A discogram is a test that can help to determine if back pain is coming from the discs. Discograms are also performed to assist in preoperative planning for candidates for a lumbar spinal fusion.
The discographer places a needle into the center of the disc through an area in the patient’s back. Radiographic dye is then injected into the disc, and if injecting the dye recreates the patient’s normal pain (concordant), it is then inferred that the specific disc is the source of pain for the patient. If the pain is unlike their normal pain (discordant) it can be inferred that even though the disc may look degenerated on an MRI scan, it is in fact not the source of the patient’s pain. The test itself is painful, but the patient needs to be awake and aware in order to tell the discographer what kind of pain is generated by the injection.
A bone scan is performed by injecting a small amount of radioactive marker into an intravenous line (IV). Three hours later, the patient is placed through a scanner and the radioactive marker will be concentrated in any region where there is high bone turnover.
A bone scan is sometimes performed to rule out an inflammatory process, or infection. It is also useful for diagnosing fractures not seen on an x-ray. It can also be used to determine if a compression fracture of the vertebral body is old or new, as an old fracture will not light up and a new one will.
An EMG/NCV is sometimes recommended to assess the electrical activity of nerves in the arms or legs. Compression or chronic irritation of a nerve will slow electrical conduction along that nerve. This can also result in changes affecting the muscle supplied by that nerve. By placing small needles into various muscles, these changes can be detected by EMG. Application of a small current can show slowing in NCV. They are used to diagnose nerve entraptment such as carpal tunnel syndrome, neuropathy and radiculopathy.
