My brother in law just recently had a hemicolectomy done, and during a follow up appointment with the general surgeon, he was told that he had stage 4 cancer in his stomach lining. While he was in the hospital, they did 2 catscans of his abdominal area, without dye, and an ultrasound of his stomach without dye as well. Isn t an MRI or a catscan with dye necessary to determine cancer?