Close, who is 26 on Friday, should have met Eubank for the third time after two controversial failures to win the title. The Belfast boxer gained a draw in Glasgow in May 1993 and lost on points in Belfast a year later. Many felt he had won both bouts, and he was confident of succeeding at the third attempt.
John Morris, the Board's general secretary, said: "The latest CT scan raised queries. Obviously, there has to be an investigation in our interests."
Steve Collins, the 30-year-old Dubliner who won the WBO middleweight title by stopping Chris Pyatt in Sheffield last year, is lined up to step up a division and take Close's place.
Close, who faces the possibility of having his career terminated, has said he wants a second opinion.Reuse content