MRI

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Obtain MRI* (Class II)

MRI is the study of choice for diagnosing most infectious, oncologic, and inflammatory conditions as well as evaluating neurologic deficits. This is because it is the only imaging modality to visualize the spinal cord, intervertebral discs, ligaments, and surrounding soft tissues. Even many cases of spondylolysis not seen on radiography can be diagnosed by MRI. Clinicians must be aware that MRI adds a considerable cost to an individual patient, burdens the healthcare system, and may include the risks of sedation. The development of “fast-sequence” MRI protocols that can image the complete spine in approximately 2 minutes may alter these considerations in the future, but are in the early stages of evaluation at this time.

Generally, an MRI is warranted for those patients with negative spinal radiographs who have red flags such as constant pain, nocturnal pain, radicular pain, more than 4 weeks of back pain, an abnormal neurologic examination, or any concern for infectious or neoplastic etiology. For these patients with negative radiographs but with red-flag signs or symptoms, approximately half will have a significant finding on MRI. Any patient for whom there is concern for cord compression or cauda equina syndrome should undergo emergent imaging, as these are neurosurgical emergencies, and neurologic function may be compromised with significant delay. In the otherwise stable patient without acute worsening or change in neurologic status, the decision for urgent versus outpatient MRI will likely depend on suspicion of disease, as well as resources for outpatient imaging. For instance, in the young patient unable to walk, with systemic symptoms or with pain out of proportion to physical examination, admission for urgent MRI may be warranted. If there is suspicion for a less severe etiology (eg, a herniated disc or spondylolysis), the patient can likely be reassured and instructed to obtain an outpatient MRI. For all patients with at least 1 red flag, it is recommended to obtain MRI imaging of the full spine.

The specifics of ordering an MRI will depend on clinical concern and examination findings. MRI without contrast is appropriate for most patients, particularly if investigating chronic pain, isolated radicular pain, isolated neurologic deficits, or if there is a high suspicion for a mechanical injury. Performing MRI both with and without contrast increases the sensitivity for infectious and inflammatory pathology as well as some neoplasms. Patients with systemic symptoms or physical examination findings that raise suspicion for these etiologies would benefit from additional contrast-enhanced imaging.