Tumours and polypoid lesions

NM imaging with labelled red cells can detect bleeding rates as low as 0.1ml/min and is more sensitive than angiography. Red cell study is most useful in intermittent bleeding.

Both barium studies and endoscopy of the colon have a high sensitivity to detect malignant tumours. Polyps of significant size are also readly detected. CT is sometimes used, mainly to determine the extent of involvement in adjacent structures.

Transabdominal ultrasound has a low sensitivity to detect tumours in the gastrointestinal tract, mainly because this is a hollow, and often gas-filled, organ.Endoscopy is the best modality regarding the stomach, although some tumours can be missed, and only be detected by X-ray.

PET has a place in tumour staging and detection of recurrences.