Diagnostic Value of Spinal Cord Lesion Metabolism on [18F]FDG PET/CT for the Classification of Myelopathy.

INTRODUCTION

[18F]FDG PET/CT scan is sometimes performed as part of the diagnostic evaluation of non-compressive myelopathies, but the spinal cord lesion metabolism is not systematically evaluated. We aimed to investigate the diagnostic value of spinal cord lesion metabolism on [18F]FDG PET/CT for differentiating inflammatory myelitis from neurosarcoidosis and tumoral lesions.

METHODS

We conducted a retrospective cohort study of patients presenting with spinal cord lesions who underwent [18F]FDG PET/CT. Patients were classified as primary inflammatory myelitis, neurosarcoidosis, tumoral lesions, or other etiologies. PET/CT examinations were reviewed by a nuclear medicine physician, masked to final diagnosis, who assessed the presence of hypermetabolism (qualitative analysis) and measured lesion SUVmax, lesion-to-liver ratio, and level-standardized Z-score to account for physiological uptake variability (quantitative analysis).

RESULTS

A total of 106 patients were included: 60 (56.6%) with inflammatory myelitis, 20 (18.9%) with neurosarcoidosis, 10 (9.4%) with tumoral lesions, and 16 (15.1%) with other etiologies. Hypermetabolism was found in 80.0% of tumoral lesions, 50.0% of neurosarcoidosis, and 23.3% of inflammatory myelitis. PET/CT showed good performance in differentiating inflammatory myelitis or neurosarcoidosis from tumoral lesions using qualitative analysis (hypermetabolism: sensitivity 0.77, specificity 0.80, and 0.50, respectively) and quantitative analysis (SUVmax: AUC 0.89 and 0.84, respectively). The performance of SUVmax for distinguishing inflammatory myelitis from neurosarcoidosis was low (AUC 0.55), but improved with the lesion-to-liver ratio (AUC 0.64) and level-standardized Z-score (AUC 0.65).

CONCLUSION

Spinal cord hypermetabolism on [18F]FDG PET/CT demonstrated good performance for distinguishing tumoral lesions from inflammatory or neurosarcoidosis, but lower performance for differentiating inflammatory myelitis from neurosarcoidosis.