Local-Sensitive Connectivity Filter (LS-CF): A Post-Processing Unsupervised Improvement of the Frangi, Hessian and Vesselness Filters for Multimodal Vessel Segmentation

A retinal vessel analysis is a procedure that can be used as an assessment of risks to the eye. This work proposes an unsupervised multimodal approach that improves the response of the Frangi filter, enabling automatic vessel segmentation. We propose a filter that computes pixel-level vessel continuity while introducing a local tolerance heuristic to fill in vessel discontinuities produced by the Frangi response. This proposal, called the local-sensitive connectivity filter (LS-CF), is compared against a naive connectivity filter to the baseline thresholded Frangi filter response and to the naive connectivity filter response in combination with the morphological closing and to the current approaches in the literature. The proposal was able to achieve competitive results in a variety of multimodal datasets. It was robust enough to outperform all the state-of-the-art approaches in the literature for the OSIRIX angiographic dataset in terms of accuracy and 4 out of 5 works in the case of the IOSTAR dataset while also outperforming several works in the case of the DRIVE and STARE datasets and 6 out of 10 in the CHASE-DB dataset. For the CHASE-DB, it also outperformed all the state-of-the-art unsupervised methods.

Zinc and copper retention during pregnancy: the adequacy of prenatal diets with and without dietary supplementation

Twenty-four pregnant women, in their second trimester, participated in two seven-day metabolic experiments to evaluate zinc and copper utilization from self-selected diets, with or without supplementation. Recommended dietary allowances for zinc or suggested intakes for copper were not met unless supplements of these nutrients were consumed. Zinc retentions in the unsupplemented group were 1.9 and 0.3 mg/day during the first and second metabolic periods, respectively. Zinc retentions in the supplemented group were 2.3 and 4.7 mg/day during the same two periods. Intakes above 8 mg/day resulted in positive retentions. Based on individual variation, however, intakes of 20 mg/day, the current RDA, would not be excessive although possibly some level between these two extremes would be adequate. Copper retentions in the unsupplemented and supplemented groups combined over the two balance periods were -0.02 and 0.89 mg/day, respectively. Adequate copper retention does not appear possible without the use of a supplement.