From the Guidelines
MRI with contrast is the best imaging modality to evaluate for a potential lumbar spinal abscess. This is due to its excellent tissue characterization and anatomic delineation, allowing for detailed assessment of the spinal cord, nerve roots, epidural space, and surrounding structures where abscesses may form 1. The sensitivity and specificity of MRI for spine infection are 96% and 94%, respectively, making it a highly accurate diagnostic tool 1. Gadolinium contrast enhancement significantly improves detection by highlighting areas of inflammation and infection, with rim enhancement being a characteristic finding in abscesses.
Some key benefits of MRI include:
- Superior visualization of soft tissues
- Detailed assessment of the spinal cord, nerve roots, epidural space, and surrounding structures
- Ability to demonstrate associated findings such as vertebral osteomyelitis, discitis, or cord compression
- High sensitivity and specificity for spine infection
CT with contrast would be a second-line option if MRI is contraindicated or unavailable, though it offers less detailed soft tissue resolution 1. Other imaging modalities, such as plain radiographs, CT without contrast, ultrasound, and nuclear medicine studies, have limited utility in diagnosing spinal infections due to their inability to provide detailed soft tissue visualization or anatomic detail needed for surgical planning.
The use of MRI without and with IV contrast is often utilized for the evaluation of patients with suspected spine infection, and it is essential to compare pre- and postcontrast MRI examinations to confirm areas of suspected abnormality within the spine segment(s) of interest 1. Overall, the superior soft tissue contrast and multiplanar capabilities of MRI make it the gold standard for diagnosing spinal infections.
From the Research
Imaging Modalities for Lumbar Spinal Abscess
The best imaging modality to evaluate for a potential lumbar spinal abscess can be determined by considering the following options:
- Magnetic Resonance Imaging (MRI): MRI is the preferred modality for imaging soft tissue, including spinal abscesses 2. It can provide detailed images of the spinal cord, nerve roots, and surrounding tissues.
- Computed Tomography (CT): CT scans can be useful for imaging small bony structures and, when coupled with myelography, can demonstrate soft tissue abnormalities in the spinal canal 2. However, CT may not be as sensitive as MRI for detecting spinal abscesses.
- Myelography: Myelography can be used to examine the spinal cord, nerve root bundles, and possible intrusion of the vertebral disk into the spinal canal 2. However, it is an invasive procedure and may not be necessary for initial evaluation.
Diagnostic Accuracy of Imaging Modalities
The diagnostic accuracy of MRI and CT for identifying lumbar spinal pathology, including spinal abscesses, has been evaluated in several studies:
- MRI: A systematic review found that MRI had a sensitivity of 75% and specificity of 77% for identifying lumbar disc herniation 3. However, the evidence for the diagnostic accuracy of MRI for spinal abscesses is limited.
- CT: A systematic review found that CT had a sensitivity of 77.4% and specificity of 73.7% for identifying lumbar disc herniation 4. However, there is limited evidence on the diagnostic accuracy of CT for spinal abscesses.
Clinical Considerations
When evaluating a patient for a potential lumbar spinal abscess, the following clinical considerations should be taken into account:
- Patient symptoms and medical history: A patient with severe back pain, fever, and neurological deficits may require urgent imaging to rule out a spinal abscess 5.
- Laboratory results: Laboratory tests, such as blood cultures and inflammatory markers, can help support the diagnosis of a spinal abscess 5.
- Imaging findings: Imaging findings, such as the presence of an abscess or fluid collection, can confirm the diagnosis of a spinal abscess 5.