Enhancing Sacroiliac (SI) Joint Management: Atypical Applications of SPECT/CT in Diagnosing and Monitoring Patients with SI Joint Pathology

Introduction: Guidance on the utility of SPECT/CT in diagnosing, planning, and monitoring post-operative recovery for sacroiliac (SI) joint-related pain is limited compared to chronic lumbar pain. This study illustrates two atypical applications of SPECT/CT in this context.

Methods: We analyzed electronic health records of patients who underwent SPECT/CT and SI joint fusion. We explored two scenarios where SPECT/CT provided value beyond standard management: 1) localizing the SI joint as a pain generator in three patients with residual spondylolisthesis post-lumbar surgeries, and 2) assessing contralateral SI joint recurrence versus instrumentation failure in patients with recurrent pain after unilateral fusion.

Results: Localization of SI Joint Pathology with Concurrent Spine Pathology:
Three patients with complex spine histories, including multiple lumbar fusions and epidural stimulation, reported refractory low back and pelvic pain. Despite persistent spine pathology like spondylolisthesis, SPECT/CT showed SI joint radiotracer uptake and pain improvement after injections, resulting in unilateral SI joint fusion. 2/3 patients experienced improved pain in the operative joint, while 1/3 reported sustained pain relief at 9 months post-surgery.

Post-operative Monitoring:
Two patients with chronic pain and positive provocation tests underwent SI joint injections for therapeutic relief before fusion. Persistent post-operative pain prompted SPECT/CT imaging to evaluate potential instrumentation failure and contralateral pathology. In one case, SPECT/CT indicated single level uptake and prompted an ALIF, leading to complete pain resolution at 2 years. The second patient showed stable fusion activity but new onset radiotracer in the contralateral joint, necessitating further surgical evaluation.

Conclusion : SPECT/CT demonstrates potential utility beyond simple SI joint diagnosis, aiding in pre-operative assessments for complex spine cases and post-operative monitoring. Further research is needed to establish guidelines for interpreting scintigraphy in concurrent spine and SI joint conditions.