A computerised needle navigation technique using optical tracking of a needle in an ultrasound image.
Real-time display of the tracked needle (blue) with the round sphere as the target (grey) in the ultrasound view of the kidney phantom. The ideal trajectory is shown in green.
Rationale for the device
Commercially available navigation systems are expensive. They have found routine use in Neuro- ENT and orthopaedic surgery. Their use in urology has largely been limited to prostate fusion biopsy. These technologies should promote the growth of a “slow revolution” in navigated minimally invasive therapies in endourology.
Various image-guided methods to track the precise location of a needle are now described. These technologies include electromagnetic, optical and positional device (accelerometer / gyroscope) tracking.
This work aims to investigate if a computerised needle navigation technique using optically tracked ultrasonography could improve performance of PCNL (percutaneous nephrolithotomy, a minimally invasive surgery to treat large kidney stones) renal collecting system puncture.
System design
Illustration of the setup for PCNL puncture using optically tracked needle in the ultrasound image.
Features of the AirTrak
The AirTrak uses off the shelf hardware which compared to commercial systems are relatively cheap.
A commercial stereoscopic infrared camera performs sub-millimeter fiducial detection and 3D tracking (Optitrack V120:duo, OptiTrack, Natural Point, Oregon, USA).
Tracking of the needle in the ultrasound image is a software function. Three free and open source software programs perform this function. (3D Slicer (www.slicer.org, Harvard Medical School, Boston, MA); SlicerIGT – an extension of 3D Slicer for image-guided interventions and PLUS toolkit application (Queen’s University, Kingston, ON, Canada) is used to interface between the hardware (tracking camera and ultrasound) and the 3D Slicer software.
The system has shown significantly improved performance of trainees attempting simulated PCNL puncture.
In vitro simulated needle renal collecting system puncture on a renal phantom using the AirTrak
Preliminary trial
Comparison of mean simulated tracked ultrasound (AirTrak) PCNL puncture (36 seconds) vs manual freehand PCNL puncture time (89 seconds), p=0.045.
