Diagnostic Imaging for Spondylodiscitis

Imaging Modality Selection

The American College of Radiology recommends radiography as the first imaging modality for evaluation of suspected spondylodiscitis, though it has low sensitivity for early disease 3
The American College of Radiology suggests MRI without and with IV contrast as the imaging modality of choice for suspected spondylodiscitis due to its high sensitivity and specificity 1
CT is indicated when MRI cannot be performed or when there are equivocal radiographic findings, according to the American College of Radiology 1, 3

CT without contrast provides excellent delineation of osseous detail with greater sensitivity than radiography, and is useful for identifying subtle bone erosions, soft tissue ossification, and complex anatomy of the affected vertebral segments 1, 3
The American College of Radiology gives CT without contrast a high appropriateness rating (7/9) for evaluation of suspected axial spondyloarthropathy when MRI cannot be performed 2

Plain CT has a lower risk profile by avoiding potential contrast-related complications such as nephrotoxicity, contrast reactions, and nephrogenic systemic fibrosis in at-risk patients 3
Plain CT is lower in cost compared to contrast-enhanced studies, does not require IV access, and provides excellent visualization of bony details 1, 3

CT lacks sensitivity for direct inflammatory changes of early infection, and has low sensitivity (6%) for the identification of epidural abscess 1, 3

The optimal imaging algorithm for suspected spondylodiscitis is to start with plain radiographs, followed by MRI without and with contrast if radiographs are negative or equivocal, and plain CT without contrast if MRI is contraindicated or unavailable 1, 2, 3

Relying solely on CT for early diagnosis of spondylodiscitis may lead to false negatives due to its limited sensitivity for early inflammatory changes 3
Performing both non-contrast and contrast-enhanced CT unnecessarily increases radiation exposure without adding significant diagnostic value, according to the American College of Radiology 2, 5
Assuming that contrast enhancement will significantly improve diagnostic accuracy for spondylodiscitis is not supported by evidence 1, 2