MRI Scan

First of all, the science bit

To begin with, let's give it its full name. MRI stands for Magnetic Resonance Imaging and it's a radiology technique which uses magnetism, radio waves, and a computer to produce images of your body which will give a range of useful information to your consultant.

The layman's version

You've probably seen one on TV the odd time, but if you haven't, an MRI scanner is a giant tube surrounded by a circular magnet. The patient is placed on a moveable bed, which is then rolled into the tube.
Images are then produced by the MRI scanner which are quite detailed and can detect tiny changes of structures within the body.

Does it hurt and are there any risks?

Firstly, we can guarantee you that it won't hurt a bit. MRI scanning is totally painless and has the added advantage of avoiding x-ray radiation exposure. There are no known side effects of an MRI scan.

If you're prone to claustrophobia, however, you should mention it to your consultant as well as the radiology staff. A mild sedative may be given prior to the scan to help keep you calm in the confined space of the MRI scanner.

You should note that patients with heart pacemakers, metal implants, or metal chips or clips in or around the eyes cannot be scanned with MRI because of the effect of the magnet.

When are MRI scans used?

In the same way that an X-Ray would be used to detect a possible bone break, an MRI is used as a very accurate method of disease detection throughout the body. Surgery can be deferred or more accurately directed when your consultant has read the results of your MRI scan.

It can be used to examine or detect:

  • Trauma to the head or brain
  • Brain aneurysms
  • Tumours of the brain
  • Tumours or inflammation of the spine
  • Strokes
  • Problems with the vertebrae or discs of the spine
  • The structure of the heart and aorta
  • Glands and organs within the abdomen
  • The structure of the joints, soft tissues, and bones of the body

What to expect at your MRI scan

  • Because MRI involves a form of magnetic scanning, you will be asked to remove all metallic objects before your scan.
  • You need to lie very still and breathe normally during the procedure. You will be able to communicate with the MRI technologist throughout the test, so if you feel any way claustrophobic, you can be immediately released from the MRI tube.
  • You will hear loud, repetitive clicking noises during the scanning - this is nothing to worry about and is completely normal.
  • Sometimes, you may be injected with contrast agents which increase the accuracy of the images.
  • The scanning time depends on the exact area of the body, but ranges from thirty minutes to an hour and a half.

Getting your results

After the MRI scan is finished, the computer generates visual images of the area of the body that has been scanned and these images are transferred to film. This film is given to a radiologist who is specially trained to interpret the MRI images. A report is sent to the doctor who requested the MRI scan - usually your G.P. or Consultant - who can then discuss the results with you.

CT Scan

First of all, the science bit

You'll normally see it referred to by either of its shortened forms - CT scan or CAT scan - but its full title is a Computerized Axial Tomography scan.

It is an x-ray procedure which combines many x-ray images with the aid of a computer to generate cross-sectional views and, if needed, three-dimensional images of the internal organs and structures of the body.

The layman's version

While a conventional X-ray is used to view bones in the body, CT scanning is the route to go when your medical team are trying to differentiate between normal and abnormal structures. It is used mainly to provide information for procedures such as biopsies, or to form an opinion on the treatment of suspected cancers.

Does it hurt and are there any risks?

CT scanning is completely painless. In many ways, it's like a normal X-ray that takes more time. The only mild discomfort you may experience is if iodine-containing contrast material needs to be injected into your body and you suffer an allergic reaction.

This is very rare and usually results in itching or a rash which goes away quickly. If you have a history of allergy, you should let your doctor and the radiology staff know of the problem.

A CT scan is also a very low-risk procedure. The amount of radiation you receive during a CT scan is minimal. As always, however, make sure you mention it if you are pregnant, in which case an ultrasound scan may be used instead.

When are CT scans used?

CT scans are carried out to examine the internal structures of the body such as:

  • The head after injuries or to detect tumours and infections
  • The spine and vertebral discs
  • The density of bone - to detect osteoporosis
  • The chest - to identify tumours, cysts, or infections
  • Body organs such as the liver, gallbladder, pancreas, spleen, aorta, kidneys, uterus, and ovaries.

What to expect at your CT scan

You will probably be asked to avoid food and fluids for several hours before the scan - especially when contrast material is being used. All metallic materials (including jewellery, belt buckles, etc.) and also some clothing may be removed as they can interfere with the clarity of the images.

You are placed on a movable table, and the table is moved into the path of a large donut-shaped machine. X-ray images are taken around the body and your scan can take from thirty minutes to an hour and a half.

It is important that you remain as still and quiet as possible. The CT technologist will tell you when to breathe or hold your breath during a scan of the chest and abdomen. The technologist will also keep an eye on you through an observation window during the scan and there will be an intercom to let you talk to each other if you need any clarification on various instructions.

Getting your results

After the CT scan is finished, a report is sent to the consultant or GP who requested the scan, and he will discuss the results with you as soon as possible.

The PET Scan

First of all, the science bit

The very charmingly-called PET scan stands for a positron emission tomography scan. It's a very specialised imaging technique that uses short-lived radioactive substances to produce three-dimensional coloured images of how those substances are functioning within the body.

The Layman's Version

During a PET scan, you will be injected with radioactive substances which have a very short lifespan, so cause little or no damage to your body.

The PET scanner is made up of complex electronic equipment which records gamma rays and, from these, provides an image of the area where the radioactive substances are located.

You may sometimes be required to have both a PET scan and a CT scan as this can provide more accurate imaging than using them separately. 

Does it hurt and are there any risks?

A PET scan is a very low risk procedure - and totally painless into the bargain. The overall experience is very similar to having an X-ray.

When are PET scans used?

PET scanning provides information about the body's chemistry that can't be obtained through other procedures. They study metabolic activity or body functions and are used mostly in the fields of cardiology, neurology, and oncology for the following purposes:

  • To assess the benefit of coronary artery bypass surgery
  • To identify causes of childhood seizures and adult dementia
  • To detect and grade tumours
  • To view metabolic processes within the body

What to expect at your PET scan

You will be lying on a table that slides into the middle of the PET scanner. The entire process takes about 2 hours while the scan itself takes a few minutes, depending on the area of the body to be scanned.

Getting your results

After the PET scan is finished, a report is sent to your G.P. or to the consultant who requested the scan. Your G.P. or consultant can then discuss the results with you.