Magnetic Resonance Imaging in Differentatial Diagnosis of Pyogenic Spondylodiscitis and Tuberculous Spondylodiscitis

Infectious spondylodiscitis is characterized by the involvement of two adjacent vertebrae and the intervening disc. Incidence rate of the disease is estimated at 0.4-2 cases per 100000 per year. Staphylococcus aureus is the most common infectious agent causing pyogenic spondylodiscitis. Non-pyogenic infections of the spine are most frequently caused by Mycobacterium tuberculosis, and fungi. Clinical symptoms are nonspecific. Early diagnosis and appropriate treatment can prevent unfavorable irreversible sequela for the patient. Significant developments in techniques of imaging of pathological tissues raised expectations among the clinicians regarding possibility to distinguish between tuberculous spondylodiscitis and pyogenic spondylodiscitis on MR images. The aim of this study was to identify and differentiate between features of tuberculous and pyogenic spondylodiscitis on MR images.

We performed retrospective analysis of MR images obtained from 34 patients with confirmed spondylodiscitis (18 with pyogenic spondylodiscitis, and 16 with tuberculous spondylodiscitis). Data acquisition was performed using 1.5 T MRI scanners where images were obtained using similar protocols. T2 TIRM and T1-weighted images with and without contrast enhancement were subject to assessment in coronal, axial and sagittal planes.

Characteristic features of pyogenic spondylodiscitis include: involvement of the lumbar spine, ill-defined paraspinal abnormal contrast enhancement, diffuse/homogeneous contrast enhancement of vertebral bodies, low-grade destruction of vertebral bodies, hyperintense/homogeneous signal from the vertebral bodies on T2 TIRM images. Prevailing features of tuberculous spondylodiscitis included: involvement of the thoracic spine, involvement of 2 or more adjacent vertebral bodies, severe destruction of the vertebral body, focal/heterogeneous contrast enhancement of vertebral bodies, heterogeneous signal from the vertebral bodies on T2 TIRM images, well-defined paraspinal abnormal contrast enhancement, paraspinal and epidural abscesses, meningeal enhancement at the affected spine level.

Comparison of MR images of patients diagnosed with pyogenic spondylodiscitis and tuberculous spondylodiscitis allowed identification of individual characteristics for preliminary differentiation between TB and infectious spondylodiscitis and thereby enabling proper treatment.