Taking in less salt each day could do more for your health than you realize.  Michelle Gielan has that story and more in today's health watch report.  There may one day be an easier and more comfortable way to detect colon cancer.  Israeli researchers successfully used a blood test in 150 patients to check for levels of "CD24."  It's a protein produced during the early stages of colon cancer and may play a role in the spread of tumor cells.  Experts say more research is needed to confirm the findings before the test can be used for widespread colon cancer screening.  Small cuts in salt intake could do big things for your health.  New research suggests cutting back on salt by just half a teaspoon a day could dramatically cut the number of cases of heart disease and death.  In fact, if more Americans would just "hold the salt," one-hundred thousand lives could be saved.  Doctors may soon have a way to test for post-traumatic stress disorder.  Using a brain imaging device, researchers found differences in brain activity between people with PTSD and healthy people.  They now want to confirm the findings in a larger study -- the team says having a test for PTSD could speed up treatment.  Those are some of today's top medical stories.  I'm Michelle Gielan, CBS News, New York.