A recent publication from researchers at Mayo Clinic set out to describe a possible technique for performing thoracic facet joint injections using ultrasound guidance. Previously published articles have described a technique for a fluoroscopically guided approach to thoracic facet injections, though neither study assessed the accuracy of this technique or the use of additional control imaging beyond an arthrogram shown with fluoroscopy for verification. These fluoroscopic imaging modalities are costly, are bulky, and expose the patient and clinician to ionizing radiation, thus the exploration into ultrasound-guided thoracic facet injections.
In the research done at Mayo Clinic, a single examiner used ultrasound to localize paired thoracic facet joints from T1-2 through T10-11 on a fresh frozen cadaveric specimen. This was done using a 2- to 5-MHz curvilinear transducer over the target facet in the sagittal plain with the cadaver in the prone position. Target facets were identified using the most inferior rib as a starting point and scanning medially toward its axial attachment and further medially and slightly superior over the most caudal thoracic facet (T11-12).
After identification, injections were performed using a long-axis or "in-line" approach with continual visualization of the needle into each facet joint. After needle placement, computed images were obtained from a fluoroscopy machine capable of 3-dimensional reconstruction to assess the location of the needle tips. Following, 0.5 mL of an iodinated contrast agent was injected, and another 3-dimensional reconstruction was performed to assess the location of the injected agent.
The results showed sixteen of 20 injections (80 percent) performed showed intra-articular contrast spread. The published article suggests this technique is feasible for performing thoracic facet joint injections using ultrasound guidance. Further verification of this technique, and modification if applicable, should be performed before directly applying this technique in a clinical practice setting.
See PubMed for the full article.