[X-ray diagnosis of colorectal carcinoma today--a determination of where we stand].

Long-term prognosis of this malignant and frequent disease can be improved only by early diagnosis of small polyps and of carcinomas in the early stage. It is necessary to coordinate high-quality colon contrast medium enemas (double-contrast method) and hypotension with coloscopy and endoscopic removal of polyps. If a colon carcinoma is identified, it is additionally also necessary--probably mostly by colon enema--to exclude preoperatively a metachronous second carcinoma which can be expected in about 5% of the cases. Ultrasound and computed tomography will help in visualising advanced carcinomas that have already passed the wall and are borderline cases in respect of operability, as well as in identifying lymph node and liver metastases, besides in identifying complicating local perforations. Proof, however, is only rendered by a positive finding. It will be necessary to determine at what extent magnetic resonance can be useful in this context.