Evaluation of Retrospective Fusion of SPECT and MRI in Back Pain: A Pilot Study

Objective: MRI is the preferred spinal imaging modality, but lacks metabolic information, while SPECT/CT provides functional information on osteoblastic activity. We aimed to determine if retrospective fusion of SPECT and MRI (SPECT/MRI) enhances disease site identification and reader confidence compared with SPECT/CT or MRI in chronic back pain refractory to medical management. Methods: One hundred and eighteen patients with chronic back pain not responding to medical management and investigated with MRI and SPECT/CT were selected. Two readers compared SPECT/MRI images to sequential reviews of SPECT/CT and MRI, MRI, and SPECT/CT alone. Potential pain generator sites and diagnostic confidence for each modality were recorded. New findings on SPECT/MRI were reviewed at a multidisciplinary meeting (MDM), and potential management changes were recorded. Results: Diagnostic confidence for SPECT/MRI (4.99) was higher than sequential SPECT/CT and MRI (3.8), MRI (3.6), or SPECT/CT (3). SPECT/MRI did not detect new disc disease, but found more sites (1%) in patients with known disc disease compared with other modalities. SPECT/MRI detected more patients and sites of endplate and facet disease compared with other modalities. It found 25% more patients and 49.5% more sites for endplate disease; 31.3% more patients and 46.7% more sites for facet disease compared with sequential review of SPECT/CT and MRI. The MDM review did not change the management for new disc disease sites. However, in 19 (25.6%) patients with new endplate disease, 45 (38.1%) patients with additional endplate disease, 20 (16.9%) patients with new facet disease, and 45 (38.1%) patients with additional facet disease, management changes were adopted. Conclusions: SPECT/MRI in refractory back pain detects additional disc, endplate, and facet disease sites and new patients compared with sequential SPECT/CT, MRI, or SPECT/CT alone, potentially leading to management changes.