Comparison of diagnosis colorectal cancer between ctscan and barium enema?

Depends on size: Can see the blood supply of tumour mass on a cat scan.. But small polyps do not show... Be does not see polyps, but does see tumour.. Colonoscopy with a perfect prep is the gold standard for large and small.

CT is better: Barium enema detects about 30%–50% of cancers detected by colonoscopy (the "gold standard".) at centers of excellence, ct colonography (or "virtual colonoscopy") can be as sensitivity as colonoscopy in detecting polyps and cancers. http://www.cancer.gov/cancertopics/pdq/screening/colorectal/healthprofessional.

See below : Barium enema will just show what is inside of the colon, while ct scan will also show information about lymph nodes and possible metastasis (spread of disease).