Detailed imaging techniques to help identify polyps and cancer
Virtual colonoscopy (also known as Computerised Tomographic Colonography - CTC) is a procedure that uses a series of advanced imaging that permits minimally invasive evaluation of the colon and rectum without the need for sedation.
A computer puts the pictures together to create detailed images that may show polyps and anything else that seems unusual on the inside surface of the bowel.
If the detailed images show polyps and anything else that seems unusual and your doctor wishes to perform a biopsy, you will need to have a normal colonoscopy.
It has an established place in investigation of symptomatic patients and following incomplete colonoscopy.
The risk for procedure-related complications is low, although CT involves larger radiation doses than the more common, conventional x-ray imaging procedures.
Clinical trials are comparing virtual colonoscopy with commonly used bowel cancer screening tests.
Other clinical trials are testing whether drinking a contrast material that coats the stool, instead of using laxatives to clear the colon, shows polyps clearly.
Mangetic Resonance Imaging (MRI)
An MRI (Magnetic Resonance Imaging) scan uses magnetism to build up cross-sectional pictures of your body.
MRI of rectal cancers is currently proposed as a technique for pre-operative staging of rectal cancers and as a technique for re-imaging cancers following pre-operative radiotherapy.
Before the scan, you may be given an injection of dye into a vein in the arm, to improve the image.
The scan takes about 30 minutes, during which time you will lie inside a chamber which is often long and narrow.
This can feel claustrophobic so talk to the doctor or nurse if you are feeling scared.
People who have heart monitors, pacemakers or certain types of surgical clips cannot have an MRI because of the magnetic fields.
Magnetic Resonance Colonography (MRC)
Several studies indicate that magnetic resonance colonography (MRC) could become an alternative to Computerised tomographic colonography (CTC) for imaging the large bowel, not having the disadvantage of radiation exposure.
Video-capsule endoscopy has become an important tool for investigation of disorders of the small bowel. While there is interest in its potential for imaging the large bowel, the place for video-capsule colonoscopy is still uncertain.