Strategies for imaging and diagnosis in spinal disorders

1

What are the major objectives of spinal imaging tests?

Common reasons to order spinal imaging studies are to:

• 1.

  Rule out serious spinal pathology, such as tumor or infection.

• 2.

  Screen the spinal column for injuries following trauma.

• 3.

  Identify and assess spinal cord and/or nerve root compression.

• 4.

  Identify and evaluate spinal instabilities and deformities.

• 5.

  Create a topographic map to guide surgical intervention.

• 6.

  Identify spinal levels intraoperatively.

• 7.

  Evaluate the results of operative and nonoperative treatment.

2

What steps can the clinician take to minimize inappropriate use of diagnostic imaging tests?

• 1.

  Perform a detailed history and physical examination before ordering any imaging tests.

• 2.

  Formulate a working diagnosis to explain symptoms and guide testing.

• 3.

  Order the imaging study best suited to evaluate the suspected pathologic process based on the working diagnosis, as well as the sensitivity, specificity, and accuracy of each imaging modality.

• 4.

  Order imaging tests only when the information obtained from the test will affect medical decision making.

• 5.

  Consider ways to limit radiation exposure when ordering imaging tests.

3

What imaging modalities are used in the evaluation of spinal disorders?

• Plain radiographs

• Magnetic resonance imaging (MRI)

• Computed tomography (CT)

• CT-myelography

• Nuclear medicine studies

• Angiography

• Ultrasound

• Fluoroscopy

4

What is one of the greatest challenges facing patients and physicians regarding the use of spinal imaging tests for evaluation of spinal pain?

Both patients and physicians tend to overestimate the ability of modern imaging tests to detect symptomatic spinal pathology and guide treatment. Each imaging modality—radiograph, CT, MRI, bone scan—is extremely sensitive but relatively nonspecific. Studies have documented that spinal imaging reveals abnormalities in at least one-third of asymptomatic patients. One of the major challenges in utilization of imaging tests is to determine the clinical relevance of abnormal spinal morphology. This determination is especially challenging when one attempts to distinguish imaging abnormalities likely to have clinical relevance from those that are part of the normal aging process or part of a normal sequence of postoperative healing. In the absence of clinical assessment, imaging tests cannot determine whether a specific spinal structure is responsible for symptoms. Excessive emphasis on imaging tests without clinical correlation is hazardous to both the patient and physician, and may lead to inappropriate treatment.

5

When should I order a spine radiograph?

Plain radiographs are the most commonly ordered initial imaging study for evaluation of the spinal column. Indications to order spinal radiographs include:

• For diagnosis of spinal conditions, such as spinal degeneration, instability, fracture, spinal deformity, tumors and infection.

• To provide follow-up regarding progression of a spinal disease process.

• To evaluate progression of a spinal deformity.

• As part of preoperative planning prior to spinal procedures.

• For intraoperative localization of spinal levels (i.e., spinal enumeration).

• To provide postoperative assessment following spinal surgery.

• To identify postoperative adverse events, such as postsurgical instabilities, pseudarthroses, transition syndromes, and spinal implant failures.

6

What are the major advantages of using plain radiographs to assess spinal disorders?

• Inexpensive and readily available

• Provide rapid assessment of a specific spinal region or the entire spinal axis (occiput to sacrum) in orthogonal planes

• Weight-bearing (standing) and dynamic studies (flexion-extension views, side-bending views) may be obtained

• Plain radiographs are useful to assess osseous structure, vertebral alignment, spinal deformity, and implant position following spinal surgery

7

What are the major disadvantages of using plain radiographs to assess spinal disorders?

• Radiographs have a low sensitivity and specificity for identification of symptomatic spinal pathology. It must be appreciated that age-related degenerative changes are present equally in symptomatic and asymptomatic populations.

• Radiographs cannot visualize the spinal cord, nerve roots, and other soft tissue structures, such as intervertebral discs and spinal ligaments.

• Radiographs cannot diagnose early-stage tumor or infection as significant bone destruction (at least 30%–40% of bone mass) must occur before a radiographic abnormality is detectable.

8

When should I order a spine MRI?

An MRI is indicated if the clinical history and physical examination suggest a serious spinal condition (i.e., tumor, infection, or traumatic injury), if severe or progressive neurologic deficits are present, or when evaluation of the spinal canal and/or nerve root canals is required prior to spinal injections or surgical procedures. Caution is necessary when considering a spine MRI in patients with nonspecific axial pain, as positive findings of spinal degeneration may be unrelated to a specific patient’s pain syndrome, as such findings are commonly observed in asymptomatic patients.

9

What are the major advantages of using MRI to assess spinal disorders?

• Avoids ionizing radiation

• Provides imaging in orthogonal planes

• Visualizes an entire spinal region and detects pathology at transition zones between adjacent spinal regions

• Provides excellent visualization of pathologic processes involving the disc, thecal sac, epidural space, neural elements, paraspinal soft tissues, and bone marrow

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