  Background: Out-of-plane lesions pose challenges for CT-guided interventions.
Augmented reality (AR) headset devices have evolved and are readily capable to
provide virtual 3D guidance to improve CT-guided targeting.
  Purpose: To describe the design of a three-dimensional (3D) AR-assisted
navigation system using HoloLens 2 and evaluate its performance through
CT-guided simulations.
  Materials and Methods: A prospective trial was performed assessing CT-guided
needle targeting on an abdominal phantom with and without AR guidance. A total
of 8 operators with varying clinical experience were enrolled and performed a
total of 86 needle passes. Procedure efficiency, radiation dose, and
complication rates were compared with and without AR guidance. Vector analysis
of the first needle pass was also performed.
  Results: Average total number of needle passes to reach the target reduced
from 7.4 passes without AR to 3.4 passes with AR (54.2% decrease, p=0.011).
Average dose-length product (DLP) decreased from 538 mGy-cm without AR to 318
mGy-cm with AR (41.0% decrease, p=0.009). Complication rate of hitting a
non-targeted lesion decreased from 11.9% without AR (7/59 needle passes) to 0%
with AR (0/27 needle passes). First needle passes were more nearly aligned with
the ideal target trajectory with AR versus without AR (4.6{\deg} vs 8.0{\deg}
offset, respectively, p=0.018). Medical students, residents, and attendings all
performed at the same level with AR guidance.
  Conclusions: 3D AR guidance can provide significant improvements in
procedural efficiency and radiation dose savings for targeting challenging,
out-of-plane lesions. AR guidance elevated the performance of all operators to
the same level irrespective of prior clinical experience.
