Twelve board-certified breast radiologists who use breast ultrasound in their practices were recruited as readers for the trial. Remuneration for 3.5 days was at the prevailing US rate. Eleven readers were from the USA and one from Great Britain. Eleven had no experience with AWBU. One had reviewed limited AWBUs 8 years earlier during the developmental phase of the technology. No reader had foreknowledge of the positivity rate of the test set.