Sonographically guided biopsy of focal lesions: a comparison of freehand and probe-guided techniques using a phantom.

Abstract

A phantom model of lesions in the human liver with simulated ribs was used to test an ultrasound probe-guided sonographic biopsy technique. The aim of the experiment was to compare biopsy time and sample quality between freehand and probe-guided methods of sonographic biopsy.Ten operators with a range of clinical biopsy experience were tested. Each operator was given two phantoms containing four targets. Each target was biopsied with both biopsy methods. Data collected included procedure time and sample quality in the biopsy specimen. Analyses were stratified by level of operator experience.Median biopsy time was 23 sec with the ultrasound probe guide and 32 sec freehand. Differences between probe-guided and freehand pairs of measurements approximately followed a normal distribution. The mean time difference between probe-guided and freehand times to complete biopsy was -20 sec (95% confidence interval, -35 to -5 sec; p = 0.01). Analysis of sample quality across all operators showed no difference.The ultrasound probe-guided technique of sonographic biopsy could be used in a complex phantom model, and there was a statistically significant time benefit with the use of probe guides compared with the freehand biopsy technique. This benefit was greatest for inexperienced operators. There was no difference in sample quality between the probe-guided and freehand techniques.