The main purposes of spine imaging are.
(1) To rule out serious spinal pathologies such as tumors or infections.
(2) To assess the relationship between spinal morphology and patient symptoms due to nerve compression, spinal deformity, or mechanical instability of the spine.
(3) Identify the degree of spinal injury.
(4) Reconstruct local anatomy to guide surgical procedures.
(5) To assess the efficacy of surgical and non-surgical treatments.
The most commonly used diagnostic imaging tests.
(1) X-ray plain film
(2) Magnetic resonance imaging
(3) CT
(4) CT-myelography
(5)Bone scan
Ancillary diagnostic tests for spinal disorders.
(1)Bone densitometry: dual-energy X-ray absorptiometry is widely used for the assessment of bone density;
(2) Discography: This symptom provoking test is performed by performing a lumbar disc injection to determine if a particular degenerated lumbar disc is the source of the pain;
(3) Small joint injections: Local anesthesia or steroid hormone injections in the small joint region can provide diagnostic information or induce anesthetic effects;
(4) Selective spinal nerve block: local anesthesia or steroid hormone injection around a segment of the spinal nerve can provide diagnostic information or induce anesthetic effects;
(5) Angiography: Vascular structures adjacent to the spine can be visualized by CT angiography or magnetic resonance angiography;
(6) Tissue biopsy: CT-guided tissue biopsy is widely used for diagnostic studies of tumors, infections, and cases of injuries with unclear diagnoses.
Misconceptions about spine imaging.
Both patients and physicians overestimate the ability of modern imaging techniques to detect symptomatic spinal lesions and guide treatment.
No imaging method has a high sensitivity and relatively low specificity.
Many studies have reported that at least 1/3 of patients with abnormalities on spine imaging are asymptomatic.
A major challenge in the use of imaging is to clarify the clinical relevance of morphologic abnormalities of the spine, where it is particularly challenging to distinguish clinically significant imaging abnormalities from normal aging changes and normal postoperative rehabilitation processes.
In the absence of clinical evaluation, imaging cannot determine whether a particular spinal structure is the cause of symptoms.
An overemphasis on imaging at the expense of the associated clinical symptoms is dangerous for both the patient and the physician and may lead to inappropriate treatment.
How can inappropriate imaging be reduced?
(1) Take a detailed history and perform a physical examination before performing imaging studies;
(2) Derive a diagnosis that can explain symptoms and guide treatment;
(3) Prescribe the most appropriate imaging test to identify a suspicious lesion based on the diagnosis;
(4) Prescribing only those imaging requests that provide information useful for medical decision making.
Classification of common spinal disorders.
(1) Degenerative disease
(2) Trauma
(3) Tumors
(4) Infections
(5)Spinal deformity
(6)Congenital diseases
(7)Inflammatory diseases
(8)Metabolic diseases
(9) Extra-spinal diseases similar to spinal lesions
What are the conditions that require a spine x-ray?
X-rays are the basic spine imaging test. It is not necessary to order a spine x-ray for every patient with cervical or lumbar spine pain. Patients with cervical, thoracic or lumbar spine pain who require a spine x-ray include
(1) Patients younger than 20 years of age or older than 50 years of age;
(2) Patients who have failed non-surgical treatment for 6 to 8 weeks;
(3) Patients with a history of trauma (excluding fractures);
(4) complaints of pain at rest or nocturnal pain, history of tumor, fever, unexplained weight loss (exclude tumor or infection).
The main advantages of X-ray plain films are.
(1) Plain films are cheap and easy to take.
(2) Can provide a rapid assessment of a specific spinal region (cervical, thoracic, lumbar) or the entire spine (from occiput to sacrum).
(3) Weight-bearing (standing) position films and power position films (flexion-extension and lateral bending) can be provided for study.
(4) Plain films can be used to confirm the normal bony structure, vertebral alignment and structural integrity of the spine.
Major disadvantages of radiographs.
(1) The sensitivity and specificity of radiographs to identify symptomatic spinal lesions is low, and age-related degenerative changes occur in both symptomatic and asymptomatic populations.
(2) X-rays do not reveal neural structures and other soft tissue injuries (e.g., intervertebral discs).
(3) X-rays cannot diagnose early tumors or infections because significant bone destruction (40% to 60% of the bone) occurs before abnormalities are detected on X-rays.
In what cases is MRI of the spine necessary?
(1) MRI is indicated if clinical symptoms and physical examination suggest a serious spinal problem and the X-ray plain film does not provide sufficient diagnostic information.
(2) Before ordering an MRI, the clinician should consider how the information provided by the spinal MRI will contribute to the medical decision making for a particular patient.
Key benefits of MRI:
(1) Avoids ionizing radiation.
(2) Provides images in mutually perpendicular planes.
(3) Visualizes the entire spinal region and avoids missing lesions in the excess area between two adjacent spinal regions.
(4) Provides perfect images of the lesion area, including the intervertebral disc, dural sac, epidural space, nerve components, paraspinal soft tissue, and bone marrow.
Major disadvantages of magnetic resonance examination:
(1) MRI does not show bony anatomy as well as CT.
(2) Many intracorporeal devices (e.g., pacemakers, drug pumps, spinal stimulators) are contraindications to MRI.
(3) Patients with claustrophobia have difficulty performing this exam.
What conditions require a CT scan?
CT scan is more helpful when there is a single indication of a bony abnormality. common conditions that CT scan can help diagnose include: fractures, small joint arthritis, spondylitis and spondylolisthesis.
The main advantages of CT scans are.
(1) The best choice for evaluating bony anatomy.
(2) Multiple tomographic images can provide images in mutually perpendicular planes by reconstruction (coronal, sagittal, and three-dimensional images).
(3) CT is feasible when MRI is contraindicated (cardiac pacemaker).
Major disadvantages of CT scan.
(1) Ionizing radiation.
(2) Poor visualization of nerves.
(3) Obvious lesions may be missed.
Indications for performing bone scans.
(1) Screening for metastatic disease of the skeletal system.
(2) Screening for metastatic tumors of the spine, primary bone tumors, disc infections, or vertebral osteomyelitis.
(3) To evaluate the biological behavior associated with bone damage, such as Buffon’s interarticular defect or degenerative changes in small joints.
(4) To help diagnose sacroiliac joint lesions, such as infection or arthritis.
(5) To diagnose fractures in areas that are difficult to visualize on X-ray (e.g. occult fractures of the sacrum).
Major advantages of bone scan.
(1) Bone scan provides a good way to quickly screen for abnormalities in the skeletal system and is particularly useful for tumors and infections.
(2) Bone scan is an effective method for clarifying the biological behavior associated with bone damage, such as distinguishing acute and chronic vertebral fractures or acute and chronic localized vertebral defects.
(3) It can be performed by planar and tomographic imaging (SPETCT).
Major disadvantages of bone scan.
(1) Bone scan has high sensitivity and low specificity.
(2) Bone scan does not provide sufficient information for surgical planning.
(3) Certain tumors, such as multiple myeloma or certain purely osteolytic metastases, do not show significant osteogenic activity on bone scan because they do not stimulate an obvious osteogenic response.