Hybrid Bone SPECT/CT Imaging in Evaluation of Chronic Low Back Pain: Correlation with Facet Joint Arthropathy

Background: Evidence to support the use of bone hydroxydiphosphonate (HDP) single photon emission computed tomography (SPECT/CT) in patients with facetogenic low back pain (LBP) is still limited. In this study we compared the scintigraphic patterns on bone SPECT/CT with the degree of structural facet joint (FJ) degeneration on CT in patients with LBP.

Methods: Ninety-nine consecutive patients with LBP were prospectively evaluated. Patients with known or suspected malignancy, trauma, infectious processes, chronic inflammatory diseases, and previous surgery were excluded. The effect of LBP on the daily quality of life was assessed with the Oswestry disability index (ODI). The Pathria grading system was used to score FJ degeneration on CT scans. The correlation between the degree of FJ degeneration and osteoblastic activity on SPECT/CT was analyzed with Kappa statistics.

Results: Ninety-nine patients were included (59 female, mean age 56.2 years). The mean ODI score was 38.5% (range, 8% to 72%). In all, 792 FJ (L2-3 to L5-S1) were examined. Of the FJs, 49.6% were Pathria grade 0-1 (normal to mild degeneration) on CT, 35% were grade 2 (moderate degeneration), and 16% were grade 3 (severe degeneration). Sixty-seven percent of the patients had scintigraphically active FJs on SPECT/CT. Sixty-nine percent of Pathria grade 3 FJs were scintigraphically active; 5.5% and 16.8% of Pathria grade 0-1 and Pathria grade 2, respectively, were active. Of the metabolically active FJs, 71.4% were at the L4-5/L5-S1 levels.

Conclusions: The ability of SPECT/CT to precisely localize scintigraphically active FJs may provide significant improvement in the diagnosis and treatment of patients with LBP. In this study we demonstrate that in >40% of FJs, the scintigraphic patterns on SPECT/CT did not correlate with the degree of degeneration on CT.