Overview of Mammoscintigraphy
Breast cancer is on the rise and is one of the most common types of cancer. It used to be thought of mainly as a disease that affects older women, but it’s becoming more common in women in their 30s and 40s. Increased awareness and screening are leading to more cases being diagnosed. Furthermore, monitoring after treatment is becoming more common, which is improving study results and survival rates.
To help reduce the negative effects and death rates from breast cancer, we’re making technological advances and expanding the ways we can detect it at earlier stages. There are several ways to test for breast cancer, such as doing an at-home physical check, having a doctor perform a physical exam, or using imaging tests like a mammogram, tomography, ultrasound, MRI (Magnetic Resonance Imaging), or PET (Positron Emission Tomography) scan. A less commonly known and used test is called scintimammography or mammoscintigraphy.
Scintimammography is a kind of nuclear medicine imaging test. It has been used as an additional tool alongside mammography—especially in specific circumstances like when there are changes after surgery, unclear mammogram results, monitoring after chemotherapy, and in suspected cases of cancer in multiple parts of the breast. MRI has mostly replaced scintimammography because it provides similar information and more, like a high-quality evaluation before surgery. However, there isn’t agreement among healthcare professionals about exactly when scintimammography should be used, so there are ongoing studies trying to determine its usefulness.
These studies have looked at various statistical data to figure out the importance of scintimammography. They’ve examined things like its ‘positive predictive value’ (how often a positive result correctly shows that the patient has breast cancer), and how often it produces false negatives (a person has breast cancer but the test says they don’t) and false positives (a person doesn’t have breast cancer but the test says they do). Mammograms have a low positive predictive value because they often give false positives. But, if used together with another method, the positive predictive value can increase, leading to better patient care and satisfaction.
It’s been shown that cancerous parts of the breast absorb radiopharmaceuticals (medical substances containing radioactive material) more than normal tissue. The diagnostic evaluation involves injecting technetium 99m sestamibi (a type of radiopharmaceutical) into the bloodstream and then taking images of the breasts. Other types of technetium can be used, but they’re less sensitive.
Anatomy and Physiology of Mammoscintigraphy
The substance used for a special kind of breast scan, known as technetium 99m sestamibi, normally appears in certain parts of the body such as salivary glands, thyroid, heart muscle, liver, and gallbladder.
If this substance is found at a higher level than usual in the breast tissue, it could signal that there is cancer present. If the breast shows only a low, even level of this substance, this is usually considered a normal result. Areas with uneven, widespread levels of the substance are typically not a sign of cancer. Whereas, it’s important to also look at the armpit area (known as the axilla), as this can highlight if there is cancer that has spread to lymph nodes from an area of the breast where there is an increased level of this substance.
However, increased levels in the folds of the armpit can sometimes be misleading and just be due to the normal workings of the body, rather than being a sign of cancer spread. Side images from the scan can help to identify this misleading scenario by showing a shallow and line-like appearance.
Why do People Need Mammoscintigraphy
There’s some debate about when to use a test called scintimammography, mainly because a different test, magnetic resonance imaging (MRI), is often used for similar reasons. However, scintimammography is commonly used in certain situations. For instance, it can help when mammograms (breast x-rays) are hard to understand or seem to indicate possible cancer. It can also be helpful in diagnosing spread of breast cancer to the underarm (axillary) lymph nodes, monitoring how well chemotherapy is working, and examining the breasts of patients with implants.
When a Person Should Avoid Mammoscintigraphy
There are some conditions that might make it unsafe to have a scintimammography, a special type of breast imaging test. Medical professionals are still discussing these conditions, but most of them might not completely prevent the test, but rather make it more risky to perform. For example, testing pregnant or breastfeeding women could put the unborn child or infant at high risk due to exposure to radiation.
Additionally, the test should not be carried out if the patient has recently undergone medical procedures like cyst removal, needle usage for tissue selection, and surgical tissue removal. It’s generally suggested to wait 2 weeks after minor procedures and up to six weeks after major ones. This waiting period is to make sure that any changes in the body after the surgery don’t affect the test results and lead to incorrect assumptions, known as false positives.
The test should also be avoided during menstruation, and also, if one is sensitive to technetium 99m – the radioactive substance used in this test.
Equipment used for Mammoscintigraphy
A standard scintillation camera, a kind of camera that detects radiation, is used. This camera is equipped with a specific attachment— called a low-energy/high-energy collimator—that helps to focus the radiation it detects. On this camera, a setting that controls the kind of energy the camera detects is adjusted to a very specific level. This setting is centered over the 140 keV photopeak of technetium 99m, a commonly used radioactive tracer in medicine. In simple terms, the camera is tuned to detect a specific type of energy that is emitted by this tracer. This helps doctors to clearly see what is happening inside your body.
Who is needed to perform Mammoscintigraphy?
A scintimammogram is a type of breast imaging test that requires various healthcare professionals to work together. This team includes radiologists (doctors who specialize in diagnosing and treating diseases using medical imaging), nuclear medicine physicians (doctors who use radioactive substances to diagnose or treat disease), nuclear medicine technicians (people trained to use the equipment safely), and engineers or workers who operate a special machine called a cyclotron. It also involves the people who manage hospital schedules to make sure everything happens smoothly and on time.
Each of these team members play an essential part in making the scintimammogram happen. All their efforts ultimately aim to assist in diagnosing and treating breast diseases more accurately. So, when you go in for a scintimammogram, remember it’s a complex operation involving many skilled professionals, all working together to look after your health.
Preparing for Mammoscintigraphy
No special preparation is necessary if you are scheduled to have a scintimammogram, which is a type of breast scan. A medical professional who specializes in nuclear medicine will be there to explain the process and help perform the test. Before starting, they will make sure you’re comfortable lying face down on a firm surface with your arms stretched over your head. You will be asked to change into a hospital gown and take off all clothes and jewelry.
They will run the scan using a special device called a scintillation camera and will follow the recommended check procedures from the Society of Nuclear Medicine to ensure that the scan provides the best possible picture. This general guidelines help to ensure that the examination is performed with the highest quality and accuracy.
How is Mammoscintigraphy performed
Medical images can be collected using two technologies, planar imaging and single-photon emission computed tomography. These methods involve injecting a substance called technetium 99m into a vein in your upper arm (opposite to the side where the problem is suspected). If there is a possibility that both breasts could show unusual findings, the substance is then injected into a lower limb. After the injection, about 10 ml of saline solution is given as well.
When it’s time for imaging, you will lie face-down with the healthy breast pressed against the table. This position helps keep the healthy breast out of the picture as much as possible and minimises distractions in the image. You’ll keep your arms raised above your head while turning your head away from the machine that takes the pictures. The machine (or detector) is then positioned against you.
The images are usually taken between 5 and 10 minutes after the injection. There are a few different images that will be taken to get a full view. They will include both sides of each breast, the underarm area, and the front of the chest wall. If it’s necessary to place a mark on the breast for future reference, this is done after the breast is properly positioned to ensure it doesn’t move and change the mark’s position relative to the abnormal area.
Technetium 99m has a unique characteristic. It’s also taken up by the heart muscle, so extra processing of the images is needed to tell the difference between signals coming from the breast and the heart.[11]
Possible Complications of Mammoscintigraphy
The procedure we’re discussing is not typically very invasive and usually has minimal side effects. But, it can occasionally cause complications. These could include the leakage of the substances we use for scans (known as radiopharmaceuticals) into surrounding tissues, or even an allergic reaction to these substances. We refer to this leakage as extravasation. Although this sounds concerning, you should know that the extravasation of a commonly used radioactive substance, Technetium 99m, does not generally harm the tissues around it. Normally, there would be no need for surgical intervention.
Allergic reactions to these scanning substances are quite rare. However, if they occur or if we suspect you might have a higher risk for an allergic reaction, we use guidelines given by the American College of Radiology. This involves preparing you with medicines that reduce inflammation (corticosteroids) and medicines that tackle allergies (antihistamines). Plus, we’ll have emergency medicines ready to go in case any symptoms of an allergic reaction start to show up. These medicines include epinephrine, which can quickly stop a severe allergic reaction, and labetalol, which can help manage symptoms such as fast heart rate and high blood pressure.
What Else Should I Know About Mammoscintigraphy?
Scintimammography is a type of test that’s used to improve the way we detect breast cancer. Its main aim is to make it more likely that we’ll correctly spot cancer when it’s there, which helps in two ways. Firstly, it cuts the overall costs for treating the disease because it means we don’t need to do as many tests. Secondly, it makes the experience better for patients because it means they won’t need to go through the stress and discomfort of as many biopsies, which are tests that involve taking a small sample of tissue from the breast.
Right now, scintimammography isn’t used very often. This is mainly because MRI scans are the more popular choice for these types of exams. However, if more research is done and it’s proven to work well, scintimammography could become an important tool in breast cancer diagnosis.
