CEA test: Carcinoembryonic antigen test is to detect response to therapy in cancer patients, especially colon cancer, with normal range of less than 2.5 (less than 5 in heavy smokers). Note that a positive test may not always be indicative of cancer.
Os Trigonum Syndrome. An Os Trigonum is a small, extra bone found at the back of the ankle in approximately 5-10% of people. Often it goes completely unnoticed, not causing any problems.
In geometry, an octagon (from the Greek á½ÎºÏÎ¬Î³ÏÎ½Î¿Î½ oktÃ¡gÅnon, eight angles) is an eight-sided polygon or 8-gon. A regular octagon has SchlÃ¤fli symbol {8} and can also be constructed as a quasiregular truncated square, t{4}, which alternates two types of edges. A truncated octagon, t{8} is a hexadecagon, t{16}.