The differential diagnostic potential of SPECT/CT to detect osteomyelitis in foot or ankle: a systematic review.

Purpose: Diagnosing osteomyelitis in the foot/ankle region is challenging primarily due to anatomical constraints. While bone biopsy is the gold standard, non-invasive methods such as SPECT (single photon emission computed tomography) and MRI are sensitive but lack specificity. This study aims to evaluate SPECT/CT's potential, integrating functional and structural imaging, to improve osteomyelitis diagnosis in this region.

Methods: A systematic review following PRISMA guidelines and the Cochrane Handbook was conducted, including comprehensive research across major databases (inception to October 2022). Diagnostic studies using SPECT/CT for suspected foot/ankle bone lesions or inflammation were included. We carried out descriptive analysis, SROC curve generation, and calculated mean sensitivities and specificities. Subgroup analyses were conducted for various tracers, CT resolutions, and evaluation strategies. Sensitivity and heterogeneity analyses, bias risk, and publication bias were assessed.

Results: Eleven diagnostic studies (463 patients) were reviewed, with seven focusing on diabetic patients. Tracers included labeled leukocytes (WBC), antigranulocyte antibodies, phosphonates (BS), and gallium citrate. Clinical follow-up was the primary reference standard. Mean sensitivity of SPECT/CT for osteomyelitis diagnosis was 93.8% (95% CI: 89.7-96.4%), and specificity was 84.6% (95% CI: 65.1-94.2%). WBC SPECT/CT was more specific (79.4%) but less sensitive (89.2%) than BS SPECT/CT (specificity 46.5%, sensitivity 93.1%). Combined tracers yielded the highest mean specificity (96.4%).

Conclusion: SPECT/CT shows promising diagnostic performance for osteomyelitis in the foot/ankle region, especially when applying combined tracer methods. It is particularly advantageous in chronic, postoperative, and post-traumatic cases, offering added value compared to MRI.