Utilization of an Ultrasonography-Computed Tomography Fusion System in the Lumbar Spine

Fluoroscopy and computed tomography (CT) are standard imaging modalities for spinal interventions but expose patients and health care professionals to ionizing radiation. Ultrasonography-CT (US-CT) fusion systems enable co-registration of real-time ultrasonography with pre-existing CT images, offering enhanced anatomical visualization without radiation. This study evaluates the feasibility and accuracy of a US-CT fusion system for vertebral level identification.

Seventeen patients scheduled for lumbar CT were enrolled. Using a GE Logiq E9 US-CT fusion system, lumbar vertebrae (L1-L5) underwent imaging in the prone position, with facet joints and sacroiliac joints as coregistration landmarks. A randomly selected vertebra was marked with a pin, and its level was verified by a subsequent CT image.

In 17 patients, 15 vertebral levels (88%) were correctly identified using the US-CT fusion system. Facet joints and sacroiliac joints were reliable landmarks for coregistration, enabling synchronized ultrasonography and CT visualization. Two errors occurred, likely due to pin displacement or misidentification.

The US-CT fusion system is a promising tool for lumbar vertebral identification, with the potential to reduce radiation exposure during spinal procedures. This observational study has several limitations, including a small sample size and an operator learning curve. Further studies are needed to optimize its application; however, its potential clinical relevance remains high.