Safe electrode trajectory planning in SEEG via MIP-based vessel segmentation

Stereo-ElectroEncephaloGraphy (SEEG) is a surgical procedure that allows brain exploration of patients affected by focal epilepsy by placing intra-cerebral multi-lead electrodes. The electrode trajectory planning is challenging and time consuming. Various constraints have to be taken into account simultaneously, such as absence of vessels at the electrode Entry Point (EP), where bleeding is more likely to occur. In this paper, we propose a novel framework to help clinicians in defining a safe trajectory and focus our attention on EP. For each electrode, a Maximum Intensity Projection (MIP) image was obtained from Computer Tomography Angiography (CTA) slices of the brain first centimeter measured along the electrode trajectory. A Gaussian Mixture Model (GMM), modified to include neighborhood prior through Markov Random Fields (GMM-MRF), is used to robustly segment vessels and deal with the noisy nature of MIP images. Results are compared with simple GMM and manual global Thresholding (Th) by computing sensitivity, specificity, accuracy and Dice similarity index against manual segmentation performed under the supervision of an expert surgeon. In this work we present a novel framework which can be easily integrated into manual and automatic planner to help surgeon during the planning phase. GMM-MRF qualitatively showed better performance over GMM in reproducing the connected nature of brain vessels also in presence of noise and image intensity drops typical of MIP images. With respect Th, it is a completely automatic method and it is not inuenced by inter-subject variability

The energetics of cycling on Earth, Moon and Mars

From 1885, technological improvements, such as the use of special metal alloys and the application of aerodynamics principles, have transformed the bicycle from a human powered heavy transport system to an efficient, often expensive, object used to move not only in our crowded cities, but also in leisure activities and in sports. In this paper, the concepts of mechanical work and efficiency of cycling together with the corresponding metabolic expenditure are discussed. The effects of altitude and aerodynamic improvements on sports performances are also analysed. A section is dedicated to the analysis of the maximal cycling performances. Finally, since during the next decades the return of Man on the Moon and, why not, a mission to Mars can be realistically hypothesised, a section is dedicated to cycling-based facilities, such as man powered short radius centrifuges, to be used to prevent cardiovascular and skeletal muscle deconditioning otherwise occurring during long-term exposure to microgravit

Tibolone and endometrial safety in menopause

Objective: Hormone replacement therapy (HRT) may increase the quality of menopausal women life. In this study we have evaluated the effects of Tibolone on the endometrium for three years and compared them to those observed in HRT patients and controls. Methods: The study was carried out on seventy post-menopausal patients; of these 32 received tibolone, 2.5 mg per day, 22 went through HRT (17 beta-estradiol, 50 microg twice a week with oral dydrogesterone, 5 mg per day) and 16 were not treated. All the patients underwent aspiration cytology in order to assess the basal conditions of the endometrium; this examination was repeated after 3 years. Results: After three years the rate of atrophic endometrium was 90% in the women who were being treated with tibolone and 60% in the patients who were receiving HRT, while the proliferative endometrium was respectively 10% and 40% (p<0.005). Conclusions: Tibolone treatment is safe for the endometrium. The use of continuous combined HRT requires a closer endometrium surveillance