Feasibility of Hybrid 67Gallium-Citrate SPECT/CT Fusion Imaging for Identifying Patients with Osteomyelitis Awaiting Ostectomy

PurposeCo-existence of ischemia and osteomyelitis strongly increase the risk of limb amputation, however, there is no established non-invasive assessment. This single-center cohort study used propensity score-matched analysis. We evaluated the clinical feasibility of hybrid 67Ga-citrate single photon emission computed tomography and X-ray computed tomography (SPECT/CT) for early diagnosis, severity assessment, and prognosis determination in these patients. Method We enrolled consecutive patients with suspected osteomyelitis with mean follow-up of 5.5 years. All patients underwent 67Ga SPECT/CT before and 4 weeks after treatment. Osteomyelitis diagnosis was based on histopathology and bacteriology of surgical sample, bone probing, or imaging follow-up. The diagnostic accuracy of bone resection rates and long-term prognoses were determined based on the target-to-background ratio (TBR). Results Among 90 patients who underwent 67Ga SPECT/CT imaging, the initial average TBR of 67Ga-citrate accumulation was 9.1 ± 12.3. TBR significantly improved following treatment (4.3 ± 3.8, p < 0.01, Wilcoxon test), and the rate of limb salvage was 80%. After propensity score matching, the pre-treatment TBR cutoff for bone resection was 10.1 (sensitivity: 85%, specificity: 82%, area under the curve: 0.87). Significant differences in long-term prognosis following bone resection were also observed often when above this cutoff point (TBR ≥ 10.1, 85.2% vs TBR < 10.1, 17.2%, p < 0.001, log-rank test). Conclusions Coupling of hybrid 67Ga-citrate SPECT/CT fusion imaging by TBR analysis revealed severity thresholds for bone resection, and could be used to assess long-term limb prognosis. 67Ga SPECT/CT fusion imaging may aid in making decisions regarding cases of suspected osteomyelitis.Trial registration:UMIN000022208, date of registration. Registered 1 January 2012, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000009900