Frequency of Discordance between Facet Joint Activity on Technetium Tc99m Methylene Diphosphonate SPECT/CT and Selection for Percutaneous Treatment at a Large Multispecialty Institution

BACKGROUND AND PURPOSE:The clinical impact of facet joint bone scan activity is not fully understood. The hypothesis of this study is that facet joints targeted for percutaneous treatment in clinical practice differ from those with reported activity on technetium Tc99m methylene diphosphonate SPECT/CT.MATERIALS AND METHODS:All patients with a technetium Tc99m methylene diphosphonate SPECT/CT scan of the lumbar or cervical spine who underwent subsequent percutaneous facet joint steroid injection or comparative medial branch blocks at our institution between January 1, 2008, and February 19, 2013, were identified. Facet joints with increased activity were compared with those treated. A chart review characterized the clinical reasons for treatment discrepancies.RESULTS:Of 74 patients meeting inclusion criteria, 52 (70%) had discrepant imaging findings and treatment selection of at least 1 facet joint, whereas 34 patients (46%) had a side (right vs left) discrepancy. Only 92 (70%) of 132 facet joints with increased activity were treated, whereas 103 (53%) of 195 of treated facet joints did not have increased activity. The most commonly documented clinical rationale for discrepancy was facet joint activity that was not thought to correlate with clinical findings, cited in 18 (35%) of 52 patients.CONCLUSIONS:Facet joints undergoing targeted percutaneous treatment were frequently discordant with those demonstrating increased technetium Tc99m methylene diphosphonate activity identified by SPECT/CT at our institution, in many cases because the active facet joint(s) did not correlate with clinical findings. Further prospective double-blinded investigations of the clinical significance of facet joint activity by use of technetium Tc99m methylene diphosphonate SPECT/CT and comparative medial branch blocks are needed.

Clinical examination and anatomic imaging do not reliably identify specific painful facet joints.^1–3 Prior studies suggest that technetium Tc99m methylene diphosphonate (^99mTc MDP) bone scan activity can predict if a facet joint is painful and if there will be a positive response to percutaneous intervention targeted specifically to active facet joints.^4–6 These prior studies used strict treatment of every facet joint with increased radiotracer activity on bone scan,^4–6 concluding that ^99mTc MDP SPECT can decrease the number of treated facet joints.⁴ However, those results can only be applicable if this is used in clinical practice and is feasible. Moreover, these studies did not incorporate CT scan for facet joint localization, use comparative medial branch blocks for diagnosis, include clearly blinded patients and proceduralists, or examine the impact of ^99mTc MDP bone scan results in actual clinical practice. Such shortcomings limit the conclusions of these prior reports and indicate the need for further examination of the clinical usefulness of ^99mTc MDP facet joint activity. In addition, evaluation of the impact of imaging in actual practice is important because the efficacy demonstrated in clinical studies often does not translate into true clinical effectiveness when the ideal rigorous methods of the efficacy study are no longer applied.⁷ That is, the effect of real-life variables such as clinical findings suggesting facet joint pain on a specific side or level and the variability of physician experience and philosophy should be evaluated to confirm or refute the impact of controlled studies on actual clinical practice and to identify areas in need of future investigation.In our anecdotal experience, the specific facet joints referred for percutaneous facet joint intervention are sometimes widely discordant from those with reported activity on ^99mTc MDP SPECT/CT. Specifically, we have seen some patients with suspected facetogenic pain where the ^99mTc MDP SPECT/CT scan does not seem to demonstrate concordant facet joint activity in the location or even on the side of pain. We have also observed that many facet joints with bone scan activity do not seem to correlate with a clinical facet joint pain syndrome. However, the concordance of facet joint bone scan activity and targeted facet joint treatment in actual clinical practice is not well described. Furthermore, the clinical rationale for imaging-procedural discrepancy is not known.The hypothesis of this study is that facet joints that are targeted for percutaneous treatment in clinical practice differ from those with reported activity on ^99mTc MDP SPECT/CT scans.