Role of magnetic resonance imaging in differentiating tuberculous spondylitis from pyogenic spondylitis in a TB endemic area

Background: Infectious spondylitis is an infection by a specific organism of one or more components of spine, namely the vertebra, intervertebral discs, paraspinal soft tissues, and epidural space. Magnetic resonance imaging (MRI) of the spine is gold standard in imaging to assess anatomical abnormalities of the spine and surrounding structures. Methods: This cross-sectional observational study was conducted in the Department of Radiology Narayan Medical College and Hospital Sasaram, Bihar (India), where tuberculosis is endemic from July 2022 to September 2023. It included 40 patients, purposively sampled, adhering to strict inclusion and exclusion criteria. Sensitivity, specificity and accuracy of MRI in discriminating tuberculous spondylitis from pyogenic spondylitis were compared against histopathological diagnosis and differences in MRI findings between these conditions were obtained. Results: In this study, 93% patients with tuberculous spondylitis had an enhanced signal with well-defined margins. Meanwhile, pyogenic spondylitis provided an ill-defined margins in 72.7% patients. Most of the patients 82.7% with tuberculous spondylitis showed thin and smooth wall paravertebral abscesses, while pyogenic spondylitis showed an irregular and thick wall paravertebral abscesses in 45% patients. A total of 72.4% patients with tuberculous spondylitis indicated involvement of ≥3 vertebral bodies. 100% patients with pyogenic spondylitis showed an abnormal contrast enhancement of the intervertebral discs. It was identified that tuberculous spondylitis had sensitivity, specificity, and accuracy values of 100%, 84.6%, and 95.2% respectively. For pyogenic spondylitis, the corresponding values were 84.6%, 96.6%, and 93%. Conclusions: MRI was accurate for differentiation of tuberculous spondylitis from pyogenic spondylitis. A well-defined paraspinal abnormal signal, a thin and smooth abscess wall, subligamentous spread to three or more vertebral levels, and less likely involvement of intervertebral discs were more suggestive of tuberculous spondylitis than pyogenic spondylitis.