Accuracy evaluation of a 3D printing surgical guide for breast-conserving surgery using a realistic breast phantom

To prevent recurrence after breast-conserving surgery (BCS), it is imperative to secure a clear resection margin, and magnetic resonance imaging (MRI) is useful for predicting this. Although MRI is highly accurate in predicting the extent of a tumor, it is difficult to quantitatively mark the tumor area directly on the patient's breast skin using MRI. Therefore, we developed a 3D-printed breast surgical guide (3DP-BSG). The 3DP-BGS is positioned on the breast using the guideline pointing to the opposite nipple and clavicle notch, centering on the nipple of the breast with the tumor. Then, the tumor was visualized by injecting blue-dye into the breast along the guide's columns using a syringe. For the quantitative evaluation of 3DP-BSG, the experiment must be done in the simulated environment. However, since it is difficult to construct the environment in the clinical field, we have fabricated a realistic breast phantom using an MRI. For modeling the 3DP-BSG, the phantom was scanned using computed tomography (CT), and. Based on these images, the 3DP-BSG was modeled to mark a 5-mm safety margin on a patient's breast skin by inserting a 16-gauge intravenous catheter. Then, the breast phantom was scanned by CT for quantitative evaluation. The insertion point measurement error (mean ± standard deviation) was 2.513 ± 0.914 mm, and the cosine similarity of the trajectories was 0.997 ± 0.005. This 3DP-BSG exhibits high accuracy in tumor targeting and is expected to facilitate precise BCS by providing a quantitative measure of the tumor area to surgeons.