Objectives: High-grade Modic changes and infectious discitis are distinct spinal pathologies that often appear similar on MRI but require very different management. This study sought to identify distinguishing clinical and radiographic features and to develop a diagnostic algorithm to improve accuracy in differentiation.
Design: A retrospective review of 10 patients with suspected Modic changes or infectious discitis was performed. Clinical data including presenting symptoms, inflammatory markers, and culture results were analyzed. MRI findings were evaluated with emphasis on endplate morphology, marrow edema patterns, and paraspinal soft tissue involvement. A diagnostic algorithm was then constructed based on these findings and literature synthesis.
Results: Patients with Modic changes primarily presented with localized back pain in the absence of systemic features. Imaging showed marrow signal abnormalities limited to the endplates, without paraspinal collections. In contrast, patients with infectious discitis demonstrated elevated ESR and CRP, occasional fever, and MRI findings of irregular endplate erosions, disc signal hyperintensity, and paraspinal or epidural extension. Multilevel involvement occurred in 17% of infectious discitis cases. Modic change cases were managed with anti-inflammatory strategies including corticosteroid injection or basivertebral nerve ablation, while discitis cases required intravenous antibiotics and close monitoring. Diagnostic ambiguity was greatest in high-grade Modic type 1 changes due to imaging overlap with early infection
Conclusions: Differentiating Modic changes from infectious discitis requires integration of clinical, laboratory, and imaging findings. Key discriminators include inflammatory markers, tutional symptoms, and the presence of paraspinal soft tissue changes. The proposed diagnostic algorithm provides a practical framework to guide clinical decision-making, reducing misclassification and ensuring appropriate treatment.
