Practitioners will often recommend following a course of conservative (non-surgical) care, usually at least four to six weeks from the onset of back pain symptoms, before obtaining any type of diagnostic study.
CT Scan or CAT Scan stands for Computed Axial Tomography. Thin beams of x-rays are passed through the body, with the x-ray beam rotating all around the body. A computer creates an image of this “slice” of the body. Slices are obtained about 1 to 4 millimeters apart. 3D reconstruction of the slices may be done. Contrast material may be added to enhance the image. CT scans are particularly good for detecting pathologies in bony tissue. (CT to check for fusion success when you can’t get an MRI due to exclusions like metal, etc.)
DEXA or DXA stands for Dual-Emission X-ray Absorptiometry. Two x-ray beams with different energy levels are aimed at the bones. The bone mineral density can be determined from the absorption of each beam by bone. DXA is the most widely used test for osteoporosis and porous bones. (bone density/osteoporosis)
Using fluoroscopy, radiopaque dye is injected into the disc. The shape of the dye inside the disc indicates the condition of the disc. In a normal disc, the shape of the dye is that of a flattened cotton ball. A leak of the dye reveals a ruptured or fissured disc. A CT scan used to be performed following the discography. Today, discography is principally used to identify the painful disc and is called a provocative discography. Not all of the discs injected with the dye will produce pain. to determine where pain is located
An EMG (Electromyography) and a Nerve Conduction Study are usually performed together. An EMG is the recording of the electrical activity of muscles at rest and during contraction. The electrical activity is recorded through electrodes placed on the skin or through needle inserted into the muscles.
The nerve conduction study measures the responses obtained by activating certain nerves. A low electrical current is passed through a thin needle inserted into a nerve. Motor nerve conduction is assessed by stimulating the motor nerve and evaluating the electrical signal from the corresponding muscle. Sensory nerve conduction is measured by stimulating a sensory nerve to produce a signal.
Nerve conduction study and electromyography help identify pathologies of the nerves (neuropathies) and muscles (myopathies). They also indicate if it is a chronic or acute (recent) condition.
MRI stands for Magnetic Resonance Imaging. The body is placed in a powerful magnetic field. Radio waves are passed through the body. Detectors transmit the information to a computer and an image of a slice of the body is created. MRI provides outstanding detail of soft tissue structures of the body, such as discs, ligaments, and spinal nerves. The size of the magnet means that pacemakers, aneurysm clips, or loose metal in pockets is not allowed. Metal spine hardware will not come loose, but may cause blurring of the images near the metal.
Nuclear Medicine Bone Scan
A radioactive tracer is injected in the blood stream and taken up by bone tissue. As the tracer degrades, gamma rays are emitted. A gamma scanner is passed over the body to detect the amount of radiation in all the bones. The scanner also produces a permanent image. Higher radiation will be visible in areas of high blood flow such as fractures, infections, inflammation, or cancer. Bone scans are useful for detecting bone pathology through the entire skeleton.
X-rays pass through the body and leave an “imprint” on the film. More or less of the x-rays is absorbed by the different human tissues, according to their respective density and thickness. Bones are dense, absorb x-rays, and appear white on the x-ray film. Organs are less dense and appear as shades of gray on the x-ray film. Air (in the lungs) appears black or dark gray on the x-ray film. X-rays provide a good visualization of bones.
Fluoroscopy is the equivalent of a “live x-ray”. An intermittent beam of x-rays is passed through the body and picked-up by a detector, which creates an image on a screen. Fluoroscopy is used for placement of needles, guidewires, pins, or catheters. It is used during surgery and during other procedures, such as discography and myelography.Read more about Emerging Imaging in Musculoskeletal Medicine!
Niteesh Bharara, MD, DABPMR
Virginia Spine Institute