When to Order Imaging for Myelopathy: ACR Appropriateness Decoded

When to Order Imaging for Myelopathy: ACR Appropriateness Decoded

A patient presents to the emergency department with rapidly progressing bilateral leg weakness, sensory changes, and new-onset urinary retention. The differential is broad, but spinal cord pathology—myelopathy—is high on the list. The next step is imaging, but the choice between MRI with or without contrast, CT, or CT myelography can be complex, especially when balancing diagnostic yield against patient factors and resource availability. Making the right initial choice is critical for timely diagnosis and intervention. This guide decodes the American College of Radiology (ACR) Appropriateness Criteria for myelopathy to clarify the evidence-based path forward.

What Does the ACR Guidance on Myelopathy Cover?

The ACR Appropriateness Criteria for Myelopathy focus on the initial imaging evaluation for patients presenting with signs and symptoms suggestive of spinal cord dysfunction. This includes a range of clinical presentations, from acute onset of weakness and sensory deficits to a more chronic or progressive decline in function. The guidelines are designed to help clinicians select the most suitable imaging modality to identify the underlying cause, which could be compressive (e.g., disc herniation, tumor, epidural abscess), inflammatory (e.g., transverse myelitis), ischemic (e.g., spinal cord infarct), or degenerative.

These criteria specifically address non-traumatic myelopathy. They do not apply to patients with a clear history of acute spinal trauma, where different imaging algorithms (such as the NEXUS criteria and dedicated trauma protocols) are indicated. The guidance also presumes that a thorough neurologic examination has been performed to localize the suspected level of the spinal cord lesion, which helps define the “area of interest” for imaging.

What Imaging Should I Order for Myelopathy? Recommendations by Clinical Scenario

The ACR provides clear, evidence-based recommendations for the initial imaging of myelopathy, with Magnetic Resonance Imaging (MRI) emerging as the dominant first-line modality due to its superior soft-tissue contrast and ability to directly visualize the spinal cord. The recommendations are consistent for both acute and chronic presentations.

For a patient with Acute onset myelopathy. Initial imaging. or Chronic or progressive myelopathy. Initial imaging., the ACR guidelines are identical. MRI of the spine area of interest without IV contrast and MRI of the spine area of interest without and with IV contrast are both rated as Usually appropriate. An unenhanced MRI is often sufficient to identify compressive causes like severe stenosis or disc herniation. The addition of intravenous contrast is crucial when there is suspicion of an inflammatory process (e.g., multiple sclerosis, transverse myelitis), infection (e.g., epidural abscess, discitis-osteomyelitis), or a primary or metastatic spinal cord tumor, as these pathologies typically demonstrate enhancement.

In situations where MRI is contraindicated (e.g., patient with an incompatible implanted device) or unavailable, CT myelography of the spine area of interest is rated as May be appropriate. This invasive procedure involves injecting intrathecal contrast and can provide excellent detail of the thecal sac and nerve roots, making it a valuable alternative for diagnosing compressive lesions. Standard CT of the spine area of interest with or without IV contrast is also rated as May be appropriate, though it offers limited direct visualization of the spinal cord itself. It is primarily useful for assessing bony anatomy, calcification, or in post-operative contexts.

Modalities such as radiography (plain films), MRA, CTA, and arteriography are all rated as Usually not appropriate for the initial workup of a generalized myelopathy, as they do not adequately assess the spinal cord parenchyma for the most common etiologies.

ACR Imaging Recommendations Table for Myelopathy

Adult vs. Pediatric Myelopathy Imaging: Radiation Dose Tradeoffs

For both adult and pediatric patients presenting with myelopathy, MRI is the preferred initial imaging study. A key advantage of MRI is its lack of ionizing radiation, reflected in the Relative Radiation Level (RRL) of “O 0 mSv” for both populations. This is particularly important in children and young adults, where minimizing cumulative radiation exposure is a primary concern under the As Low As Reasonably Achievable (ALARA) principle.

When MRI is not feasible, alternative studies like CT and CT myelography must be considered. These modalities carry a radiation dose designated as “Varies,” depending on the specific protocol, the area of the spine being imaged, and the equipment used. For pediatric patients, CT protocols must be carefully tailored to reduce radiation dose, often involving adjustments to kVp and mAs settings. While CT myelography can be diagnostically necessary, the combination of radiation exposure and the procedural risks of a lumbar puncture makes it a second-line choice, especially in the pediatric population. The decision to proceed with a radiation-based study in a child should always involve a careful risk-benefit analysis.

Imaging Protocol Details for Myelopathy

Once you’ve decided on the right study, the specific imaging protocol is critical for maximizing diagnostic yield. Key parameters like slice thickness, sequence selection (e.g., T1, T2, STIR, DWI), and contrast timing can significantly impact the visibility of subtle cord pathology. Our detailed protocol guides are designed for residents, fellows, and practicing clinicians to ensure the ordered study is technically optimized.

• MRI Lumbar Spine Without Contrast

Tools to Help You Order the Right Study

Navigating imaging guidelines and protocols can be challenging in a busy clinical setting. GigHz provides a suite of reference tools designed to support evidence-based decision-making at the point of care, helping you select the most appropriate study and understand its technical execution.

The ACR Appropriateness Criteria Lookup allows you to quickly search the full ACR guidelines for thousands of clinical scenarios beyond myelopathy, ensuring your imaging orders are aligned with national standards. For detailed technical parameters, the Imaging Protocol Library offers curated, step-by-step guides for a wide range of MRI, CT, and other imaging procedures. When discussing studies that involve ionizing radiation, the Radiation Dose Calculator is a valuable resource for estimating patient exposure and facilitating informed conversations about the risks and benefits of imaging.

Why is MRI the preferred first-line imaging for myelopathy?

MRI is overwhelmingly preferred because of its exceptional soft-tissue resolution. It can directly visualize the spinal cord, detecting intrinsic abnormalities like edema, inflammation, demyelination, or infarction that are invisible on CT or X-ray. It is also highly sensitive for identifying extrinsic compressive causes such as disc herniations, tumors, or epidural fluid collections without the need for ionizing radiation or intrathecal contrast.

When should I order an MRI with contrast versus without contrast?

An MRI without contrast is often sufficient to diagnose compressive myelopathy from degenerative disc disease or spinal stenosis. You should order an MRI with and without contrast when you suspect a pathology that is likely to enhance, such as an infection (epidural abscess), an inflammatory process (transverse myelitis, multiple sclerosis), or a primary or metastatic tumor. If the clinical suspicion for these is low, starting without contrast is a reasonable approach.

What is the role of CT myelography in working up myelopathy?

CT myelography is the primary alternative imaging modality when MRI is contraindicated (e.g., due to an incompatible pacemaker or other metallic implant) or in the rare case that it is non-diagnostic. It involves injecting contrast material into the thecal sac via lumbar puncture, followed by a CT scan. It provides excellent delineation of the spinal canal and can clearly identify points of compression, though it is invasive and involves radiation.

Are plain X-rays (radiography) ever useful for myelopathy?

For the initial evaluation of myelopathy, plain X-rays are rated as “Usually not appropriate” by the ACR. They cannot visualize the spinal cord or soft tissues and are insensitive for most causes of myelopathy. Their use is limited to assessing gross bony alignment, fractures, or instability, but even in these cases, CT is far more sensitive and specific.

How does the suspected location of the lesion (e.g., cervical vs. thoracic) affect the imaging order?

The choice of modality (MRI) remains the same regardless of the suspected level. However, the neurological exam is crucial for localizing the lesion and defining the “area of interest” for the MRI. For example, a patient with upper and lower extremity signs would typically require an MRI of the cervical spine, while a patient with a sensory level on their torso would require an MRI of the thoracic spine. Imaging the entire spine may be necessary if the localization is unclear or if multifocal disease (like metastatic cancer or MS) is suspected.

Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 12, 2026