Evaluation of an interactive ultrasound-based breast tumor contouring workflow

PURPOSE: Computer-navigated breast tumor excision using tracked ultrasound is a technique for performing lumpectomies during early-stage breast cancer. An interactive method is used to contour tumors intra-operatively for excision. We evaluated this method's effectiveness in contouring the entire tumor with minimal inclusion of healthy tissue in the excision volume. Additionally, we investigated the possibility of adding a safety margin to the contoured volume to ensure that the entire tumor is contained by the contour. METHODS: We conducted a study in which 10 participants contoured 5 tumors each using the intra-operative breast tumor contouring system. We analyzed their interactions with the system and their opinions of the contouring workflow. RESULTS: We found that only 0.19% of the tumor volume was not contained by the contour on average. The addition of a 0.4 mm safety margin to the final tumor contour guaranteed that the entire tumor would be contained. We also found a correlation between the amount of time spent on contour verification and excess healthy tissue included in the contour. Users' perceptions of how well they excluded excess healthy tissue strongly correlated with reality. CONCLUSIONS: This workflow ensures that only a small amount of tumor volume is not contained by the contour and allows the radiologist confidence that they have contained the entire tumor in their contour. With the addition of a safety margin to the resulting tumor contour, the tumor can be completely contained.