According to a study presented at BritSpine (2–4 April, Warwick, UK) and published as an abstract in the European Spine Journal, there would be more than 50% missed or wrong targets if the treatment of facet joints was determined on computed tomography (CT) alone. Therefore hybrid single photon emission computed tomography (SPECT)/CT imaging could significantly improve the management of patients with low back pain as it is able to precisely localise metabolically active facet joints.
Study presenter Vittorio Russo (National Hospital for Neurology and Neurosurgery, London, UK) reported that there is little evidence to guide the use of SPECT/CT for low back pain and in particular, there are still limited data for its role in the management of facet joint arthropathy (a common cause low back pain). Therefore, Russo and colleagues correlated the degree of facet joint degeneration observed on CT scans with patterns of metabolic activity on SPECT /CT scans. They use the Pathria classification to assess facet joint degeneration on CT scans: grade 0, normal facet joint; grade 1, joint space narrowing; grade 2, narrowing and sclerosis or hypertrophy; grade 3, severe osteoarthrosis with narrowing, sclerosis, and formation of osteophytes. Of the 100 patients with low back pain evaluated in the study, 59 were female, the mean age was 56.2 years, and the mean Oswestry Disability Index score was 38.5%. Overall, 800 facet joints were analysed.
Russo reported that, according to the CT scan, 50% were grade 0–1 Pathria (normal or mild generative changes), 34% had were grade 2 (moderate changes), and 16% were grade 3 (severe degeneration). Fifty-one per cent of patients had scintigraphically active facet joints on hybrid SPECT/CT imaging—70% of the active facet joints on SPECT/CT were found at L4–5/L5–S1 levels. 57.3% of Pathria 3 grade facet joints were scinitgraphically active while 42.7% were quiescent on SPECT /CT; 2.5% and 9.2% of Pathria 0-1 and Pathria grade 2, respectively, were active. Therefore, 11.7% of normal-to-moderately degenerated facet joints (on CT) were “hot” on SPECT /CT imaging and 47.2% of severely degenerated facet joints were “not hot”.
Russo concluded that, based on results of the study, metabolic activity in the facet joint was “not always correlated” with the degree of facet joint degeneration. “The ability of hybrid SPECT/CT imaging to precisely localise metabolically active facet joints may provide significant improvements in the treatment of patients with low back pain. There would be more than 50% of ‘wrong or missed’ if considering treating facet joint arthropathy only on the basis of CT findings”, he noted.
