Diagnostic imaging terms can feel unfamiliar when you’re trying to understand a spine evaluation. This glossary defines the most common tests, structures, and conditions our clinical team references during the diagnostic process — so you can ask better questions and understand what each finding may mean for your care path.
X-ray
An X-ray uses a small amount of radiation to produce images of bony structures in the spine. Our clinical team typically orders X-rays as a first step to evaluate spinal alignment, screen for fractures, assess scoliosis, or identify signs of arthritis. X-rays provide limited soft-tissue detail — they do not visualize intervertebral discs, nerves, or ligaments — so additional imaging is usually needed when disc or nerve involvement is suspected.
MRI (Magnetic Resonance Imaging)
MRI uses a magnetic field and radio waves to generate detailed images of soft tissues, including intervertebral discs, nerve roots, ligaments, and the spinal cord. For patients with chronic back or neck pain, MRI is the preferred imaging modality because it can reveal disc damage, nerve compression, and structural changes that X-rays cannot detect. It is non-invasive and does not use radiation. Patients with certain metal implants may not be candidates for MRI. See our overview of cervical spine MRI for more on how this test is used in neck evaluations.
CT Scan (Computed Tomography)
A CT scan combines multiple X-ray images taken from different angles and uses computer processing to create cross-sectional views of bones, blood vessels, and soft tissues. CT provides superior bone detail compared to MRI and is particularly useful for evaluating complex fractures, bone spurs, or degenerative vertebral changes. For patients who cannot undergo MRI due to a pacemaker or incompatible implant, CT scanning offers an alternative for detailed spinal imaging.
Myelogram
A myelogram involves injecting contrast dye into the fluid-filled space surrounding the spinal cord, then imaging with X-ray or CT to outline the spinal cord and nerve roots. This highlights areas of compression from herniated discs, spinal stenosis, or other structural abnormalities. Myelography is used when standard MRI or CT provides insufficient detail or when MRI is contraindicated. It helps our clinical team pinpoint the specific level and cause of nerve compression before treatment planning.
Fluoroscopy
Fluoroscopy produces real-time, continuous X-ray images on a monitor — often described as a live X-ray. In spine care, fluoroscopy guides diagnostic and therapeutic injections, including nerve blocks and procedures such as annular tear repair. Real-time visualization allows our clinical team to confirm precise needle placement, navigate around delicate spinal structures, and target the specific area of concern with greater accuracy.
Electromyography (EMG)
EMG assesses the electrical activity of muscles and the motor neurons that control them. During the procedure, small needles are inserted into specific muscles to record activity at rest and during contraction. EMG can help identify nerve root compression, muscle disorders, or disrupted nerve-to-muscle signaling. For patients with muscle weakness, tingling, or numbness, EMG helps differentiate spinal nerve involvement — such as radiculopathy — from conditions affecting the muscles themselves.
Nerve Conduction Study (NCS)
A Nerve Conduction Study measures the speed and efficiency of electrical signals traveling along nerve pathways. Electrodes placed on the skin deliver mild electrical pulses to stimulate target nerves, and the response is recorded. NCS is often performed alongside EMG. Together, these tests help our clinical team assess whether nerve symptoms originate from compression in the spine or from peripheral nerve conditions elsewhere in the body.
Physical Examination
A thorough physical examination is the foundation of any spine evaluation. Our clinical team assesses posture, range of motion, muscle strength, deep tendon reflexes, and sensation. Specific tests — such as the straight leg raise or Spurling’s test — can help localize nerve impingement or disc involvement. Physical examination findings guide which imaging tests are most appropriate and help ensure diagnostic workup is targeted rather than reflexive.
Annulargram
An annulargram is a specialized procedure in which contrast dye is injected directly into an intervertebral disc under fluoroscopic guidance. The purpose is to visualize tears or fissures in the annulus fibrosus that may not be clearly seen on standard MRI. If the dye leaks through a tear or if the injection reproduces a patient’s familiar pain pattern — a finding called concordant pain — it supports a diagnosis of discogenic pain. Annulargram results can help determine whether a patient may be a candidate for biologic disc repair approaches.
Intervertebral Disc
An intervertebral disc sits between each pair of vertebrae, functioning as a shock absorber and allowing spinal flexibility. Each disc has two primary components: the annulus fibrosus (the tough outer ring) and the nucleus pulposus (the gel-like inner core). During imaging evaluation, our clinical team examines discs for signs of degeneration, herniation, bulging, or tearing — all of which are common contributors to back and neck pain. To learn more about disc anatomy in plain language, see our disc conditions glossary for patients.
Annulus Fibrosus
The annulus fibrosus is the strong outer ring of an intervertebral disc, composed of approximately 17 concentric layers of collagen fibers. It contains the nucleus pulposus, provides structural integrity to the disc, and allows the spine to flex and absorb load. On MRI and annulargram, our clinical team evaluates the annulus for tears or disruption. Annular tears can be a direct source of discogenic pain and, when significant, may allow nuclear material to migrate outward — a precursor to herniation.
Nucleus Pulposus
The nucleus pulposus is the gel-like, water-rich center of an intervertebral disc. It distributes compressive forces evenly across the disc and provides the cushioning effect between vertebrae. On MRI, a healthy nucleus appears bright on T2-weighted sequences due to its high water content. Desiccation — loss of water — signals disc degeneration, while displacement of nuclear material through an annular tear indicates herniation. Both findings influence how our clinical team approaches evaluation and treatment planning.
Annular Tear
An annular tear is a fissure or rip in the annulus fibrosus. These tears vary in severity, and not all cause symptoms — but when they do, they can be a significant source of chronic discogenic back pain. Inflammatory proteins from the disc’s interior can leak through annular tears and irritate adjacent spinal nerves. High-resolution MRI and annulargram are the primary tools for identifying these tears. Because the disc has a limited blood supply, annular tears in some patients do not heal on their own, which can lead to progressive degeneration or herniation over time. Our resources on annular tears as a root cause of back pain explain this process in greater detail.
Expert Take
Annular tears are among the most under-recognized sources of chronic low back pain. Standard imaging may miss smaller tears, and the absence of a visible herniation does not rule out significant disc pathology. Our clinical team evaluates each case individually — because the right diagnostic sequence can determine whether a patient is a candidate for non-surgical options or whether other contributors to pain need to be addressed first.
Herniated Disc
A herniated disc occurs when nuclear material pushes through a tear in the annulus fibrosus and extends beyond the disc’s normal boundaries. Depending on the location and size of the herniation, it may compress nearby nerve roots or the spinal cord, producing radiculopathy — symptoms such as pain, numbness, tingling, or weakness radiating into the arms or legs. MRI is the primary imaging method for confirming herniation, identifying its level, and assessing neural involvement. A herniated disc may also be referred to as a ruptured disc or slipped disc.
Spinal Stenosis
Spinal stenosis is a narrowing of the spinal canal or the foraminal openings through which nerve roots exit the spine. This narrowing can place pressure on the spinal cord or nerve roots, producing symptoms that may include leg pain, weakness, or numbness — particularly with walking or prolonged standing, a pattern called neurogenic claudication. Stenosis commonly results from age-related changes including disc bulging, ligament thickening, and bone spur formation. MRI and CT scanning are the primary tools for assessing the location, degree, and neural impact of stenosis. For a patient-oriented overview, see our article on common symptoms of spinal stenosis.
