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.
Figure 1: Os trigonum demonstrates lucent region (syndchondrosis) adjacent to the posterior talus; the Stieda process is a prominent posterior talar process remaining attached to the talus (note the bone cyst in the calcaneus). When the os trigonum is the cause, it is described as os trigonum syndrome.