-This work proposes a hybrid segmentation method based on Morphological Operators and on a Gaussian function constraint to delimitate the search dominium, both used for tumor segmentation purposes The Watershed operator was also used to find tumor contour. The proposed method was firstly evaluated using gear simulated images (eight and sixteen teeth with different width and height), a power speckle noise of 10% and a contrast ratio of 10:53 referred to the background. The hybrid method was also applied to 200 ultrasound (US) breast images. For assessing the segmentation performance, similarity parameters (overlap ratio, RS, normalized residual mean square value, nrv, and mean distance between contours, dmed) based on the predefined shape or on the US tumor contour depicted by an expert as a gold standard. The segmented contour of the gear simulated images obtained with the hybrid method better preserves the original shape. This finding was evident for both gears, which is particularly important since the teeth mimic contour irregularities. For the US breast images, the proposed method keeps the tumor boundaries without aggregating improper structures, resulting in RS > 50% for 91% of the images, nrv < 40% for 70%, and dmed < 5 pixels for 77% of the cases. These findings suggest that the hybrid method represents more realistically tumor contours, which is a vital diagnosis characteristic.

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Introduction Several models of venous occlusion plethysmography (VOP) aim to detect venous mechanical dysfunctions. However, such models ignore arterial contribution to plethysmographic signal. Arterial resistance is an important factor because it regulates blood inflow through veins. Furthermore, modeling arterial compliance and resistance permits evaluation of arterial pressure throughout VOP protocol. Method This study presents a new simulation model and VOP data interpretation, making it possible to estimate arterial and venous mechanical characteristics. The model was evaluated using VOP data obtained under different vascular conditions (placebo, post-ibuprofen, and post-exercise). Results Estimated mean values of venous compliance were 0.34 ml/mmHg (placebo), 0.33 ml/mmHg (post-ibuprofen), and 0.27 ml/mmHg (post-exercise). The corresponding estimated values of venous resistance were 11.55 mmHg s/ml (placebo), 10.58 mmHg s/ml (post-ibuprofen), and 8.84 mmHg s/ml (post-exercise). The estimated mean values of arteriolar resistance were 132.14 mmHg s/ml (placebo), 123.93 mmHg s/ml (post-ibuprofen), and 95.36 mmHg s/ml (post-exercise). Conclusion The estimated values are consistent with previous VOP model results and with expected physiological behavior. The proposed model can provide further information for studies using the VOP technique including studies involving exercise, reactive hyperemia, mental stress, body temperature changes, and vasomotor substance administration.