Difference between Tomosynthesis and MRI
Tomosynthesis is an imaging, or X-ray, technique that can be used to screen for early signs of breast cancer in people with no symptoms. This type of imaging can also be used as a diagnostic tool for people who are having breast cancer symptoms.
Tomosynthesis is an advanced type of mammography. The Food and Drug Administration (FDA) approved it in 2011. During Tomosynthesis, multiple images of the breast are taken. These images are sent to a computer that uses an algorithm to combine them into a 3-D image of the entire breast.
Procedure of Tomosynthesis
The procedure for Tomosynthesis is very similar to that of traditional mammography.
Tomosynthesis even uses the same type of imaging machine as traditional mammography. However, the images it takes are different. Not all imaging machines are equipped to take Tomosynthesis images.
Overall, the procedure lasts around 15 to 30 minutes.
Here’s what you should expect:
- When you arrive, you’ll be taken to a changing room to remove your clothes from the waist up and provided with a gown or cape.
- You’ll then be taken to the same machine or type of machine that performs a traditional mammogram. The technician will position one breast at a time in the X-ray area.
- Your breast will be tightly compressed like they are during a traditional 2-D mammogram.
- The X-ray tube will be positioned over your breast.
- During the procedure, the X-ray tube will move by making an arc over your breast.
- During the procedure, 11 images will be taken of your breast in 7 seconds.
- You’ll then change positions so that images can be taken of your other breast.
- After the procedure is complete, your images will be sent to a computer that will make a 3-D image of both breasts.
- The final image will be sent to a radiologist to interpret the results.
After the procedure is complete, you can resume your normal activities and diet.
If your results are normal and show no signs of cancer, you may hear from the doctor that same day.
If your results suggest you may have cancer, further testing and follow-up are needed. Result times will vary by facility.
If the results are inconclusive, the doctor may call you back in for further tests, such as an MRI or ultrasound. It may take at least 1 week to receive the results of one of those tests. However, one of the benefits of Tomosynthesis is that it results in lower callback rates, according to a 2019 study Trusted Source.
Advantages of Tomosynthesis
- More accurate overall and less likely to result in false positives
- Much greater accuracy when screening for breast cancer in people with dense breasts
- Earlier detection of breast cancer in people with breast cancer symptoms
Tomosynthesis can be used to detect breast cancer before many people ever start to have any symptoms. Tomosynthesis can often discover breast cancer years before a person or their doctor could feel it or see any symptoms.
Disadvantages of Tomosynthesis
- More radiation, in some cases. Radiation levels will vary by mammography machine. For some people receiving 3-D mammograms, there may be slightly more exposure to radiation due to more images being taken of each breast. However, the radiation levels are still low enough to meet the FDA’s safety standards. The radiation leaves your body shortly after the procedure.
- Inconsistent reconstruction algorithms. Specific algorithms for constructing the 3-D images may vary, which may affect your results.
- Variation in the images. The arc of the movement of the X-ray tube may vary, which may cause variation in the images.
Magnetic Resonance Imaging (MRI) for Breast
Magnetic resonance imaging (MRI) of the breast uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of the structures within the breast. It is primarily used as a supplemental tool to breast screening with mammography or ultrasound. It may be used to screen women at high risk for breast cancer, evaluate the extent of cancer following diagnosis, or further evaluate abnormalities seen on mammography. Breast MRI does not use ionizing radiation, and it is the best method for determining whether silicone breast implants have ruptured.
Procedure of MRI
MRI exams may be done on an outpatient basis.
You will be positioned on the moveable exam table. Straps and bolsters may be used to help you stay still and maintain your position.
For an MRI of the breast, you will lie face down on a platform specially designed for the procedure. The platform has openings to accommodate your breasts and allow them to be imaged without compression. The electronics needed to capture the MRI image are actually built into the platform. It is important to remain very still throughout the exam. This is best accomplished by making sure you are comfortable and can relax rather than trying to actively hold still tensing your muscles. Be sure to let the technologist know if something is uncomfortable, since discomfort increases the chance that you will feel the need to move during the exam.
If MRI of the breast is being performed for the sole purpose of determining if you have a ruptured breast implant, you will not be given contrast material. If the exam is being performed for any other reason, you will need to have a contrast material injected intravenously. MRI of the breast without contrast material is inadequate for identifying breast cancers.
You will be placed into the magnet of the MRI unit. The technologist will perform the exam while working at a computer outside of the room.
If a contrast material is used during the exam, it will be injected into the intravenous line (IV) after an initial series of scans. More images will be taken during or following the injection.
When the exam is complete, you may be asked to wait while the radiologist checks the images in case more are needed.
Your IV line will be removed after the exam is over.
The imaging session lasts between 30 minutes and one hour and the total examination is usually completed within an hour and a half.
MR spectroscopy, which provides additional information on the chemicals present in the body’s cells, may also be performed during the MRI exam. This may add about 15 minutes to the total exam time.
Advantages of MRI:
- MRI is non-invasive and does not use radiation
- MRI does not involve radiation
- MRI contrasting agent is less likely to produce an allergic reaction that may occur when iodine-based substances are used for x-rays and CT scans
- MRI gives extremely clear, detailed images of soft-tissue structures that other imaging techniques cannot achieve
- MRI can easily create hundreds of images from almost any direction and in any orientation
- Unlike techniques that examine small parts of the body (i.e. ultrasound or mammography) MRI exams can cover large portions of the body
- MRI can determine if a cancer has spread, and help determine the best treatment
Disadvantages of MRI:
- MRI is expensive ($1000-$1500)
- MRI will not be able to find all cancers (i.e. breast cancers indicated by microcalcifications)
- MRI cannot always distinguish between malignant tumors or benign disease (such as breast fibroadenomas), which could lead to a false positive results
- MRI is not painful, but the patient must remain still in an enclosed machine, which may be a problem for claustrophobic patients
- An undetected metal implant in a patient’s body may be affected by the strong magnet of the MRI unit
- There is a small chance that a patient could develop an allergic reaction to the contrasting agent, or that a skin infection could develop at the site of injection
- If a patient chooses to be sedated for the scanning, there is a slight risk associated with using the sedation medication