Breast Modeling Towards an Educational Tool for Breast Cancer Surgeons

Deformações da mama que ocorram devido a possíveis complicações ou procedimentos da cirurgia de remoção de cancro da mama, podem ter impacto na aparência física e afectar negativamente o estado psicológico da pessoa em causa. Estes impactos psicológicos são mais frequentes nas mulheres, visto que as mamas são socialmente vista como um ícone de feminidade e fertilidade. Quando diagnosticadas com cancro da mama, os tratamentos mais frequentes a que as doentes são sujeitas são radioterapia, quimioterapia e cirurgia. Dentro das cirurgias, a mastectomia é a que mais mulheres temem dado ser a mais radical e bastante invasiva pelo facto de ser removido todo o tecido que constitui a mama. Não obstante, hoje em dia já existem alternativas menos radicais como o tratamento conservador do cancro da mama, que é menos invasiva, pois só remove o tumor e algum tecidos circundante. As técnicas mais recentes como Breast Conserving Surgery têm como objectivo maior eficácia e a obtenção de um melhor resultado estético. Embora exista práticas de trabalho muito heterogéneas que levem a resultados estéticos diferentes. Criar uma ferramenta educacional de treino para os novos cirurgiões para BCS revela-se bastante útil para cirurgiões recém-formados. Pois a ferramenta ajudara-os a tornarem-se melhores profissionais antes de terem experiência, já que existe uma relação entre experiência e resultado estético de uma cirurgia. Estudos mostram que o resultado de uma cirurgia pode ser influenciado pela experiência do cirurgião ou seja, quanta mais experiência (número de cirurgias praticadas) este tiver, melhores serão os resultados obtidos. Para poder criar uma ferramenta de treino foram usados modelos paramétricos 3D e sintéticos para simular a superfície da mama (com ou sem deformações), o seu interior e outras estruturas como tórax e o músculo do peitoral.O utilizador tem de introduzir certos dados como: volume, tipo de mama e projecção da mesma. A densidade mámaria é representada pelos quatro tipos em classificação Breast Imaging-Reporting and Data System (BI-RADS). Para representar o tumor no modelo é essencial: o quadrante de onde se encontra na mama, estágio de desenvolvimento e a sua forma, redondo ou especulado.A ferramenta educativa, disponibiliza de uma interface, previamente testada e validada pela sua usabilidade e eficácia por varias propostas de interface.Breast deformities that occur due to possible complications or procedures of breast cancer removal surgery can have an impact on its physical appearance and adversely affect the psychological state of the person concerned. This psychological impacts happens particularly in women, since the breast is socially seen as an icon of femininity and fertility.When diagnosed with breast cancer, the most frequent treatments are radiation therapy, chemotherapy, and surgery.Within the surgeries, mastectomy is the one that most women fear since the intervention is more radical and quite invasive due to the fact that all the breast tissues are removed. Nonetheless, there are less radical alternatives such as the conservative treatment of breast cancer, which is less invasive and preserves more the breast aesthetics because it only removes the tumor and some surrounding tissues. The latest techniques such as Breast Conserving Surgery (BCS) aims to achieve greater efficiency and a better aesthetic result. Although there are very heterogeneous practices that lead to different aesthetic results.Creating an educational training framework for conservative surgery may be very useful for newly trained surgeons. The framework will help them become better professionals before obtaining experience, since there is a relationship between experience and the outcome of a surgery. Studies show that the result of a surgery can be influenced by the experience of the surgeons, ie, the more experience (number of surgeries performed) the surgeon has, better are the results obtained.In order to create a training framework, parametric and synthetic 3D models were used to simulate the surface of the breast (with or without deformities), its interior and other structures such as thorax and pectoral muscle.The inputs required to simulate the breast surface are volume, breast type and its projection. The breast density is represented by 4 types of Breast Imaging-Reporting and Data System (BI-RADS) classification. To represent the tumor in the model it is essential to know the quadrant in the breast, its stage of development and the tumor form, round or speculated.The educational tool has an interface, previously tested and validated for its usability and effectiveness between several interface prototypes

Data-driven patient-specific breast modeling: a simple, automatized, and robust computational pipeline

Background: Breast-conserving surgery is the most acceptable option for breast cancer removal from an invasive and psychological point of view. During the surgical procedure, the imaging acquisition using Magnetic Image Resonance is performed in the prone configuration, while the surgery is achieved in the supine stance. Thus, a considerable movement of the breast between the two poses drives the tumor to move, complicating the surgeon's task. Therefore, to keep track of the lesion, the surgeon employs ultrasound imaging to mark the tumor with a metallic harpoon or radioactive tags. This procedure, in addition to an invasive characteristic, is a supplemental source of uncertainty. Consequently, developing a numerical method to predict the tumor movement between the imaging and intra-operative configuration is of significant interest. Methods: In this work, a simulation pipeline allowing the prediction of patient-specific breast tumor movement was put forward, including personalized preoperative surgical drawings. Through image segmentation, a subject-specific finite element biomechanical model is obtained. By first computing an undeformed state of the breast (equivalent to a nullified gravity), the estimated intra-operative configuration is then evaluated using our developed registration methods. Finally, the model is calibrated using a surface acquisition in the intra-operative stance to minimize the prediction error. Findings: The capabilities of our breast biomechanical model to reproduce real breast deformations were evaluated. To this extent, the estimated geometry of the supine breast configuration was computed using a corotational elastic material model formulation. The subject-specific mechanical properties of the breast and skin were assessed, to get the best estimates of the prone configuration. The final results are a Mean Absolute Error of 4.00 mm for the mechanical parameters E_breast = 0.32 kPa and E_skin = 22.72 kPa. The optimized mechanical parameters are congruent with the recent state-of-the-art. The simulation (including finding the undeformed and prone configuration) takes less than 20 s. The Covariance Matrix Adaptation Evolution Strategy optimizer converges on average between 15 to 100 iterations depending on the initial parameters for a total time comprised between 5 to 30 min. To our knowledge, our model offers one of the best compromises between accuracy and speed. The model could be effortlessly enriched through our recent work to facilitate the use of complex material models by only describing the strain density energy function of the material. In a second study, we developed a second breast model aiming at mapping a generic model embedding breast-conserving surgical drawing to any patient. We demonstrated the clinical applications of such a model in a real-case scenario, offering a relevant education tool for an inexperienced surgeon