A novel finite element model-based navigation system-supported workflow for breast tumor excision.

In the case of female breast cancer, a breast-conserving excision is often desirable. This surgery is based on preoperatively gathered MRI, mammography, and sonography images. These images are recorded in multiple patient positions, e. g., 2D mammography images in standing position with a compressed breast and 3D MRI images in prone position. In contrast, the surgery happens in supine or beach chair position. Due to these different perspectives and the flexible, thus challenging, breast tissue, the excision puts high demands on the physician. Therefore, this publication presents a novel eight-step excision support workflow that can be used to include information captured preoperatively through medical imaging based on a finite element (FE) model. In addition, an indoor positioning system is integrated in the workflow in order to track surgical devices and the sonography transducer during surgery. The preoperative part of the navigation system-supported workflow is outlined exemplarily based on first experimental results including 3D scans of a patient in different patient positions and her MRI images. Graphical Abstract Finite Element model based navigation system supported workflow for breast tumor excision is based on eight steps and allows inclusion of information from medical images recorded in multiple patient positions.

Finite Element Breast Simulation for Sonography Image Registration.

In case of female breast cancer, a breast conserving excision is often necessary. For this purpose, information from multiple medical imaging techniques have to be combined. Sonography imaging is essential for dense breast tissue and the only medical imaging technique available during surgery. During sonography of the outer breast quadrants the woman is usually in contralateral posterior oblique position, being in supine orientation while holding her ipsilateral arm over the head. Thus, these images cannot be directly registered with MRI or mammography images because these imaging technologies are performed in other patient positions with hands on the side of the body. Thus, we present a novel Finite Element approach how to enable a sonography image registration by showing the first time how to transfer the supine position with the arm straight on side into a supine position with the ipsilateral arm over the head which can be used to include information from MRI or mammography images. This approach is shown and validated with 3D scanner breast surface data as proof of concept. When comparing the simulation result with a 3D surface scan in supine orientation with the arm over the head, a mean surface distance error of 1.57 mm is achieved.

Establishing and monitoring of urethral sphincter deficiency in a large animal model.

BACKGROUND: Different methods for induction and monitoring of urethral sphincter deficiency were explored in a large animal model. METHODS: Sphincter deficiency was established in female pigs by dilatation and cauterization, and amount and frequencies of voiding were monitored and explored by pad test. Sphincteric closure pressures were recorded prior to and immediately after treatment of each animal, and on day 21 by two techniques: standard urethral pressure profilometry (s-UPP) and high-definition urethral pressure profilometry (HD-UPP). Tissue samples of the urethrae were analyzed by histochemistry (AZAN- and Sirius Red staining) and by immunohistochemistry detecting desmin and fast-myosin to depict muscular tissues. RESULTS: After 3 weeks of observation animals treated by dilatation plus electrocautery presented with sphincter deficiency: measurements by both, s-UPP and HD-UPP demonstrated the maximal closure pressure reduced to baseline levels and a diminished area under the curve. Histological analyses documented, that dilatation yielded a pitted connective tissue and cauterization lead to muscle damage. Animals treated by either dilatation only or proximal injury only recovered within 3 weeks. By pad test no significant differences between untreated and treated animals or between the differently treated groups were recorded. CONCLUSION: Significant urethral sphincter deficiency can be induced in female pigs by a combination of urethral dilatation and distal electrocautery. Sphincter deficiency can be measured by standard and high-definition urethral pressure profilometry. It was maintained over 21 days after induction and correlated with visible changes in the tissue structure of the distal urethra.