President Trump underwent "advanced imaging" of his abdomen and cardiovascular system for "preventative" reasons, the White House said Monday, one day after the president told CBS News' Weijia Jiang that he had "no idea" what body parts his MRI covered during his October physical at Walter Reed National Military Medical Center. White House press secretary Karoline Leavitt read a letter from Sean Barbabella, the physician to the president, where he said the president's cardiovascular imaging "is