The scans commonly used in gynaecological cancers include ultrasound, CT, MRI, and isotope scanning.
An ultrasound scan uses sound waves. The sonic reflections are used by the computer to produce pictures of the womb and ovaries. The quality is particularly good if the probe is placed very close. That is why vaginal scanning creates high definition images of the womb. It is possible to measure tissue to an accuracy of 0.1mm.
CT (CAT) Scanning uses a high dose of radiation energy to provide a three-dimensional x-ray. It is very useful for looking at the size of tumours and gets excellent pictures of the lungs. Special contrast (either by drinking a safe dye or by injection) can be used to see blood vessels and the guts. It is generally limited to abnormalities in the abdomen that are about a 1cm in size but specific scanning can detect abnormalities in the lungs that are only few millimeter in size.
An MRI (MR or magnet) scan looks at different types of tissues. It is particularly useful in seeing contrasts in different organs and measuring tumour invasion into the body. The scan usually involves lying in a type of tunnel so it can be claustrophobic for some women, but please don’t be afraid, as it does not use radiation.
An isotope scan involves using radioactive dye. The aim is to use a dye that the tumour will absorb. If a high amount of the radioactive dye becomes trapped within the tumour, it will show up on an image. This can often be useful for identifying and removing the single important lymph node that relates to the tumor just before surgery. It is not usually used in gynaecology for any other use.
A PET scan uses the combination of isotope scanning with CAT or MRI images. It looks at metabolic activity of tissue. It is not very accurate and a tumour needs be approximately 1cm before it can be detected. It is not normally very helpful in gynaecology as a CT scan is more versatile.