Target visibility enhancement for C-arm cone beam CT-fluoroscopy-guided hepatic needle placement: implementation and accuracy evaluation.

PURPOSE: Fluoroscopy-guided hepatic intervention is limited by target visibility and respiratory movement. A feasible procedure for visibility enhancement of the key regions and targets in 2D fluoroscopic images is needed. A system was developed to improve targeting by integrating the forward projection of objects extracted from 3D cone beam CT (CBCT) volumes. The target matching accuracy during regular respiration was measured to evaluate the system.
METHOD: 3D CBCT abdominal volumes were acquired and segmented to extract different regions, including the diaphragm, hepatic vessels, bony structures, and hepatic tumor. The segmented result was rendered and projected to generate augmented fluoroscopy fusion images. The target matching accuracy by applying these procedures was evaluated for the hepatic intervention guidance. RESULT: Quantitative assessment of the target matching accuracy in the upper section of liver was performed for eight targets from four subjects. The 2D and 3D target matching accuracy were 0.98±0.37 and 1.47±0.26 mm, respectively. The 2D target matching accuracy was 1.46±0.67 mm for the target in the lower liver. This accuracy should be acceptable for the 5 mm safety margin required in clinical use.
CONCLUSION: Visibility of targets in 2D fluoroscopy was enhanced to improve interactive navigation guidance for hepatic needle placement. The target matching accuracy for the C-arm cone beam CT-fluoroscopy-guided hepatic needle targeting was sufficient for clinical use.