Whole-Spine MRI Reveals High Prevalence of Multifocal Spondylodiscitis and Identifies a High-Risk Subgroup: A Retrospective Cohort Study of 274 Patients.

Background and Objectives: Spondylodiscitis is a severe spinal infection associated with substantial mortality. Standard diagnostic imaging is often limited to the symptomatic spinal segment, which may fail to detect infection foci in other spinal regions. The prevalence and prognostic significance of multifocal spondylodiscitis remain insufficiently characterized. Materials and Methods: A retrospective single-center cohort study was conducted at the University Medical Center Mannheim, Germany. All patients with a first diagnosis of imaging-confirmed infectious spondylodiscitis treated between 2008 and 2017 were included (n = 274). Disease distribution was classified as monosegmental, multisegmental unifocal, or multifocal. The study evaluated the detection rate of multifocal disease stratified by imaging modality (whole-spine MRI vs. segmental MRI) and assessed in-hospital mortality according to disease distribution, comorbidity burden, and pathogen type. Results: Among the 139 patients who underwent whole-spine MRI, multifocal spondylodiscitis was identified in 25 (18.0%) compared with 2 out of 116 patients (1.7%) who received segmental MRI. Overall in-hospital mortality was 16.9% (46/272). Mortality was substantially higher in patients with multifocal disease (40.0%) than in those with monosegmental (13.7%) or multisegmental unifocal involvement (15.6%, p = 0.002). Increasing comorbidity burden (7.5% with no comorbidities to 27.1% with three or more; p = 0.008) and Staphylococcus aureus infection (26.2% vs. 11.0%; p = 0.010) were also significantly associated with mortality. Conclusions: Multifocal spondylodiscitis was more frequently detected with whole-spine MRI and was associated with substantially increased in-hospital mortality. These findings support consideration of a low threshold for whole-spine MRI in the primary diagnostic workup of suspected spondylodiscitis. Further prospective studies are required to confirm these findings.