Virtual colonoscopy

Virtual colonoscopy, also called computerized tomographic colonography (CTC), is a type of computerized axial tomography (so a CAT scan) done on the colon and rectum. Virtual colonoscopy is now being explored as an alternative to traditional colonoscopy due to its many advantages; it is non-invasive, comfortable for the patient, does not require sedation, and carries no risk of colon perforation. 

While the patient rests on a gurney, virtual colonoscopy uses standard CAT scan radiation to take multiple X-ray images around the body. Specialized software then analyzes the images creating a representation in perspective (2D and 3D) of the surfaces and volumes of the colon and rectum. In this way, CTC allows the doctor to visualize the walls of the colon, detecting any polyps or cancers that may exist.

It is a useful examination in patients who cannot have a colonoscopy, or do not want it.

É um exame útil em pacientes que não podem realizar uma colonoscopia ou não querem submeter-se a este exame

However, for now, virtual colonoscopy still has critical technical limitations:

• Its sensitivity needs improvement, at the moment it is only reliable for lesions bigger than 1cm; 
• It has low sensitivity for flat lesions, and for analysis of the sigmoid colon and rectum; 
• It cannot take biopsies, contrary to colonoscopies. 

Another technique being studied, also as an alternative to traditional endoscopy, is Capsule endoscopy.