Magnetic resonance imaging (MRI) of the cervical spine is a non-invasive diagnostic tool used to investigate neck pain, stiffness, or neurological symptoms extending into the arms. Unlike X-rays, MRI uses strong magnetic fields and radio waves to generate detailed images of soft tissues, such as nerves and the spinal cord. Understanding how these images are created and what normal anatomy looks like can help patients better grasp the findings in their diagnostic reports. This guide provides a framework for interpreting the visual and written information contained within a standard cervical spine MRI examination.
Understanding MRI Imaging Sequences and Views
MRI relies on different pulse sequences to contrast tissues, most commonly T1-weighted and T2-weighted images. The T1 sequence is used for anatomical definition; fat (like bone marrow) appears bright, while fluid (like cerebrospinal fluid or CSF) appears dark. Conversely, the T2-weighted sequence highlights fluid and inflammation. Water-rich tissues and the CSF surrounding the spinal cord appear bright white on T2 images, allowing professionals to identify areas of edema or increased fluid content, which often indicate injury.
Radiologists use specific viewing planes to examine the spine from multiple perspectives. The sagittal view provides a side-to-side profile, assessing the alignment of the vertebral bodies and the overall shape of the spinal canal. The axial view presents cross-sectional slices, allowing for precise assessment of the spinal cord’s circumference and the space available for the exiting nerve roots. The coronal view offers a front-to-back perspective, though it is less common for standard cervical spine analysis than the sagittal and axial planes.
Identifying Key Anatomical Structures of the Cervical Spine
The cervical spine consists of seven stacked bony blocks, labeled C1 through C7. These appear as consistent, medium-gray structures on both T1 and T2 sequences. The vertebral bodies should maintain a uniform height and rectangular shape, typically aligned in a slight forward curve known as lordosis. Between each vertebral body are the intervertebral discs, which act as shock absorbers and provide flexibility.
A healthy disc is composed of a tough outer ring (annulus fibrosus) and a gelatinous center (nucleus pulposus). On T2-weighted images, a healthy nucleus pulposus exhibits a bright white signal, reflecting its high water content. This uniform, high signal intensity is a marker of normal hydration and structural integrity, and the discs should be roughly the same height throughout the cervical spine.
Immediately posterior to the vertebral bodies runs the spinal cord, which should appear as a continuous, medium-gray structure with smooth margins, centrally positioned within the spinal canal. The surrounding CSF provides a bright contrast on T2 images, creating a distinct boundary for visualizing the cord’s contour. Lateral to the spinal cord, at each level, are the neural foramina—small bony openings through which the spinal nerve roots exit the canal. In a normal scan, these foramina should be wide and unobstructed.
Interpreting Common Abnormal Findings
Degenerative disc disease, often termed spondylosis, is the most common finding, representing age-related wear and tear. This process begins with disc desiccation, appearing as a progressive loss of the bright T2 signal within the nucleus pulposus. As the disc loses water content, it darkens on the T2 image, changing from white to dull gray, often accompanied by a reduction in overall disc height.
This loss of height changes spinal biomechanics, frequently leading to the formation of small bony spurs, called osteophytes, around the edges of the vertebral bodies. These bony changes, combined with the bulging of the annulus fibrosus, can encroach upon the space meant for the neural structures.
A more acute finding is a disc herniation, which describes the localized displacement of disc material beyond the normal intervertebral disc space. Herniations range from a broad-based bulge to a focal protrusion or extrusion, where the nucleus pulposus breaks through the annulus. On the MRI, a herniated disc appears as an outpouching mass of gray disc material that visibly indents or displaces the bright white CSF surrounding the spinal cord or nerve roots.
The severity of a herniation is determined by its impact on surrounding structures. If it compresses the spinal cord, it can cause an area of increased T2 signal change within the cord, indicating myelopathy or injury. Spinal stenosis is the generalized term for the narrowing of the canals that house the neural elements.
Central Canal Stenosis
Central canal stenosis refers to the narrowing of the main passage where the spinal cord travels, often caused by disc bulges, ligament thickening, and osteophytes.
Foraminal Stenosis
Foraminal stenosis occurs when the neural foramina—the small openings for the nerve roots—become constricted, typically by bony spurs or lateral disc material.
On axial and sagittal T2 images, stenosis is identified when the bright white signal of the CSF surrounding the cord is significantly reduced or completely effaced. Effacement means the fluid space is obliterated, showing direct contact and deformation of the spinal cord or nerve root, which signifies a more severe case.
Decoding the Radiologist’s Written Report
While the images provide visual evidence, the radiologist’s written report translates these findings into standardized medical terminology. The report is typically divided into two main sections: Findings and Impression. The Findings section offers a detailed, level-by-level description of all observed structures and abnormalities, using precise language to describe the location and nature of any changes.
Common terms used include “effacement,” which describes the obliteration of a space (e.g., CSF space due to a disc bulge), and “multilevel changes,” indicating degenerative findings at several segments. “Retrolisthesis” describes a vertebral body that has slipped backward relative to the one below it. The Impression section is the radiologist’s concise summary, often using descriptors like “mild,” “moderate,” or “severe” to qualify conditions like stenosis. Patients should focus on the Impression, as it summarizes the most clinically relevant diagnoses.