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MRI & CT

The Australian Centre for Female Pelvic and Vaginal Rejuvenation
The Australian Centre for Female Pelvic and Vaginal Rejuvenation

MRI & CT – What are they?

CT

stands for computed tomography. It used to be known as computed axial tomography.

CT uses x-rays and digital computer technology to create detailed two- or three-dimensional cross-section images of the body.

MRI

stands for magnetic resonance imaging.

MRI uses a large external field, radio-frequency pulse and 3 different gradient fields.

Both are imaging scanning procedures used extensively in the practice of medicine. CT’s are more commonly used than MRI mainly because CT is cheaper and the the machines are more accessible. They are both non-invasive, painless and relatively safe procedures. You can resume normal activities as soon as you leave. However, if you have received any sedation you should take advice about driving and the use of machinery.

CT
  • A major advantage of CT is that it is able to image bone, soft tissue and blood vessels all at the same time.
  • Suited for bone injuries, lung and chest imaging, cancer detection.
  • Widely used in Emergency departments.
  • Often ordered in gynaecology patients (but not usually ordered by gynaecologists) where is it often less useful than ultrasound or MRI.
  • Metal implants are not a contraindication for a CT scan.
  • Morbid obesity may mean that a patient might not fit into the scanner.
  • Patients do not usually feel claustrophobic during the study.
  • Adverse reactions to contrast media are uncommon (but are more common than for MRI studies).
  • CT usually is more widely available, faster, much less expensive, and may be less likely to require the person to be sedated or anesthetized.
  • The radiation from CT scans is harmful and repeated scans can even cause cancer.
  • Usually, CT is not recommended for pregnant women.
  • The CT study usually takes less than 10 minutes to perform.
MRI
  • Much higher soft tissue detail compared to CT imaging.
  • Suited for soft tissue evaluation, e.g. ligament and tendon injury, spinal cord injury, brain tumours. Also useful in gynaecological assessment of the pelvic structures and organs.
  • MRI is contraindicated in patients with cardiac pacemakers, tattoos and metal implants due to possible injury to the patient or image distortion.
  • Morbid obesity may mean that a patient might not fit into the scanner.
  • Patients often feel claustrophobic during the study.
  • Adverse reactions to contrast media is very uncommon.
  • MRI has the ability to change the imaging plane without moving the patient. Most MRI machines can produce images in any plane.
  • No biological hazards have been reported with the use of the MRI.
  • The MRI study usually takes longer than a CT study (about 20-50 minutes).
  • Generally, there are no special after-care instructions.

CT of the kidneys, ureters and bladder

MRI of the pelvis

Things to consider before your CT or MRI

The doctor may give you mild sedatives to help you relax during the procedure

Tell your doctor if you

  • have an implanted device of any kind.

  • are pregnant or think you might be pregnant.

  • are claustrophobic.

  • have any medical condition at all, particularly kidney disease.

CT
  • Any implanted device you may have such as a pacemaker or medication pump, as metal objects may distort the images.
  • Contrast material to improve the image quality. The contrast material may be taken orally or by an intravenous injection (or both).
  • You may have to go without food and drink for a certain length of time before the procedure.
  • A very obese person may be too big for the circular hole of the CT machine.
  • Nursing mothers may need to avoid breastfeeding for about 24 hours after a CT scan, if the iodinated intravenous dye was used.
MRI
  • Some metal objects can be affected by the magnetic field of the MRI scan. **Don’t ever have an MRI scan if you have a heart pacemaker!
  • The effect of MRI scanning on a fetus is unknown.
  • Before undergoing a pelvic or abdominal MRI scan, you are likely to be advised not to eat or drink for at least five hours before the procedure.

Preparation for your scan

  • You will be asked to remove all metal objects, including wristwatches, keys and jewellery. These items must be left outside the scan room.
  • In most cases, you are asked to undress and put on a cotton gown.
  • You are instructed to lie on the scanner’s table.
  • It is important to lie very still. Movement will blur or distort the pictures.
  • While it is in operation, the scanner makes noises such as knocks, loud bangs and clicks. (You may be offered earplugs. In some cases, you can listen to music through headphones if you prefer.)

After your scan

You may be asked to wait while the radiographer checks the quality of the pictures. In some cases, you may be asked to get back into the MRI scanner so that more pictures can be taken. If the pictures are satisfactory, you can get dressed and go home. 

A radiologist will examine and interpret the scan images. A report of the radiologist’s findings is sent to your doctor. You will need to make an appointment with your doctor to discuss the results. The CT or MRI scan will help the doctor to plan appropriate treatment, if necessary.

Laser Vaginal Rejuvenation Institute of Adelaide
Laser Vaginal Rejuvenation Institute of Adelaide