Overview of Breast Ultrasound
Breast ultrasound has become a widely used method for examining potential issues within the breast. Though mammograms are still considered the best way to screen for breast cancer, they can sometimes struggle with producing clear images if the breast tissue is dense. Because of this, ultrasound and MRI (Magnetic Resonance Imaging) are becoming more popular as additional techniques for breast screening.
The accuracy of detecting breast cancer significantly increases – to about 97.3% – when both mammograms and ultrasound are used. Meanwhile, the rate of false positives (when the test wrongly indicates that cancer is present) from ultrasound is estimated to be only about 2.4%.
In 2013, the ACR (American College of Radiology) BI-RADS Atlas issued guidelines on breast ultrasound terminology. This reference document contains multiple descriptions of what different breast features could indicate, allowing doctors to make a final assessment based on whichever characteristic seems most concerning.
Anatomy and Physiology of Breast Ultrasound
Breast ultrasound is a helpful tool often used by doctors to pinpoint breast lumps, whether they can be felt or not, before removing them through surgery.
A woman’s breast is made up of 15 to 20 sections, known as lobules. Each lobule has smaller channels or ducts called terminal duct lobular units (TDLUs). All these ducts lead to one common duct that carries milk towards the nipple.
There are three main areas within the breast: the premammary, mammary, and retromammary zones. These zones consist of fatty tissue, fiber-like glandular tissue, and muscle tissue. The fatty and fibrous tissue in the breast lies between two layers; the layer just beneath the skin and the deeper layer nearer to the chest muscle.
When viewed through ultrasound, the breast appears as layers that can either reflect sound waves well (hyperechoic) or absorb sound waves (hypoechoic), creating a contrast. You can think of them like different colors on a map, where each color represents a different type of tissue. For instance:
* The skin shows up as white fibrous bands (hyperechoic)
* The fat appears as lobules, or small round structures (hypoechoic)
* The breast tissue or parenchyma shows up as fibrous soft tissue (hyperechoic)
* The fat behind the breast displays as lobules (hypoechoic)
* The chest muscle or Pectoralis major appears as fibrous tissue (hyperechoic)
Another key area to examine during a breast ultrasound is the armpit or axilla. It is essential to assess this area because it contains lymph nodes and blood vessels (the axillary artery and vein). Normally, lymph nodes have a fatty central part, with thinner outer layers measuring less than 3 mm.
It’s crucial to understand how the breast receives its blood supply and how fluid drains from it. The axillary and subclavian arteries supply blood to the breast through several branches, including the internal mammary (or internal thoracic), lateral thoracic, and thoracoacromial arteries. The majority of fluid from the breast drains into lymph nodes in the same side armpit, while a smaller amount drains to lymph nodes near the breastbone. Usually, 90% of the fluid drains to the lymph nodes in the armpit and 10% to the nodes near the breastbone. In rare cases, following breast surgery like mastectomy, the fluid can drain to the other breast.
Why do People Need Breast Ultrasound
Doctors use breast ultrasound for various reasons, including:
1. Feeling a lump during a breast exam: If your doctor detects a lump during a physical check-up, they may order a breast ultrasound to further analyze it.
2. Axillary lymphadenopathy seen on a mammogram: This refers to enlarged or swollen lymph nodes under your arm. If a mammogram (a type of breast X-ray) detects this, the doctor might recommend a breast ultrasound for further investigation.
3. Women under 40 years with certain symptoms: If a young woman has specific unusual symptoms in the breast area, an ultrasound could be conducted.
4. Pregnant or breastfeeding women: An ultrasound gives a safe and effective way to examine the breasts in women who are pregnant or nursing.
5. Irregular findings on a mammogram: If a mammogram shows something suspicious, a doctor may follow up with an ultrasound.
6. Nipple discharge: If fluid comes out of the nipple without any reason, a breast ultrasound could provide valuable information to the doctors.
7. Skin retraction or nipple inversion: If the skin on the breast or nipple changes its shape or sinks inward, an ultrasound can be very useful.
8. Surgical scarring seen on a mammogram: If previous surgeries left scars that are evident on a mammogram, additional imaging with ultrasound might be used to better understand the breast composition.
9. Gynecomastia: This term refers to an abnormal enlargement of the male breasts. In such case, breast ultrasound may be done to understand the cause.
10. Suspected broken breast implants: Ultrasound can help the doctors find out whether there is a leak in the implant and whether it is inside or outside the capsule that houses the implant.
11. Needle-guided breast biopsy: If doctors need to remove a sample from the breast for testing, an ultrasound can help guide the needle to the exact location.
12. Patients getting neoadjuvant chemotherapy: A doctor might order a breast ultrasound to monitor the tumor size and response to treatment in patients undergoing chemotherapy before surgery.
When a Person Should Avoid Breast Ultrasound
It is not suitable to use breast ultrasound alone as the only method for checking for breast problems or diseases.
Equipment used for Breast Ultrasound
High-frequency ultrasound, which uses sound waves to capture images inside the body, has improved significantly over the years. It now relies on advanced probes designed with high-density or single crystal components. These components increase the clearness of the image. Another standard feature in most basic ultrasound machines is Tissue Harmonic Imaging (THI). This technology helps reduce image disruptions, providing a clearer picture.
For better image contrast, real-time compound scanning is used. This method involves using a special type of scanner called a linear array transducer. The American College of Radiology recommends this transducer operate at a minimum frequency of 10 MHz. Higher frequencies are used when detailed images are needed, and lower frequencies are used for looking deep into the body or when examining larger breasts.
When it comes to breast ultrasounds, a high-resolution scanner operating at a minimum frequency of 12 MHz is best. A larger frame that shows more of the area being examined is essential. This detailed view is particularly useful when examining larger or multiple breast issues. Other techniques include joining images together for large issues and creating 3D images for a full view.
Modern ultrasound machines even come with their own linear frequency probes that can connect to mobile imaging applications wirelessly. The software used in these machines has computer-aided detection (CAD) which helps identify unusual masses. This advancement has increased the accuracy in diagnosing health conditions.
Creating quality ultrasound images requires careful attention to technical details like the depth of the focus area, the adjustment of image brightness, and the overall image enhancement during mass issue examination. The focus area should be within the upper or middle third of the area between the chest wall and the skin. As for image brightness settings, the fat just under the skin should appear medium gray as opposed to dark or black. Additionally, setting the image enhancement too high can make some fluid-filled sacs appear solid. Multiple ultrasound images can be combined to improve resolution and get a better look at the issue’s edges.
Who is needed to perform Breast Ultrasound?
The task of performing a breast ultrasound is carried out by a trained healthcare professional. This could be an ultrasound technician who specializes in operating ultrasound machines, a radiologist who is a doctor trained in interpreting medical images, or a healthcare provider who refers you for the ultrasound and has the necessary knowledge in using and understanding ultrasound images. These professionals have all the important skills needed to carry out this task. They use the ultrasound images to evaluate your breast health in a reliable manner.
Preparing for Breast Ultrasound
Getting an ultrasound of the breast is a simple process that doesn’t usually require a lot of special preparation. The patient should remove any jewelry that might be in the area the doctor wants to look at. It’s also recommended that the patient wear comfortable, loose clothing and remove clothing from the top part of their body before the scan begins. This is done so that the doctor can easily access and examine the chest area.
How is Breast Ultrasound performed
First, a self-examination of the breasts is performed to check any lumps or masses found by the patient or doctor. After this, a type of scan called an ultrasound is conducted on both breasts, one after the other, to examine the tissue more closely.
The breasts are divided into 4 major areas for examination: the upper outer, upper inner, lower outer, and lower inner parts. If any abnormalities are found during the examination, they are marked in a way that’s similar to pointing out a time on a clock, which helps track them in future check-ups.
There are several ways to scan the breast. The most common method is to sweep the scan from top to bottom of the entire breast in a radial pattern, which looks similar to a star. This scan covers the area underneath the armpit, the area towards the breastbone, and the area towards the collarbone.
It’s also important to examine the area directly behind the nipple, even though the dense tissue here can make it difficult to see. To overcome this, the examiner can either angle the device upwards or use a special gel pad to enhance visibility.
When measuring a suspicious area, the longest part should be noted down, typically to the nearest millimeter or centimeter. Three measurements are usually given, with the first being the longest part, the second perpendicular to the longest part, and the third in a different direction from the first two.
Breasts are made up of fat and fibroglandular tissue, and they can be categorized according to the ratio of these two components. There are three categories: mainly fat, mainly fibroglandular, or a mix of the two (which could hide potential issues).
When examining any abnormal masses, several features have to be described in the report, such as shape (oval, round or irregular), orientation (parallel to the skin or not), edge (clear-cut or not), echo pattern (which describes the internal consistency of the mass), and any features directly behind the mass. Other aspects such as skin changes, swollen lymph nodes, signs of vascular abnormalities, and elasticity of the mass might also be assessed based on the case history.
If any specks of calcium known as calcifications are found, their location should be noted too – they could be inside a mass, outside a mass, or within the milk ducts. Lastly, there are certain findings that are indicative of specific conditions – for example, simple cysts, masses in or on the skin, foreign bodies, or vascular abnormalities.
Possible Complications of Breast Ultrasound
A breast ultrasound is a safe procedure that doesn’t involve any invasion into the body, and there are no complications that come from the procedure itself.
What Else Should I Know About Breast Ultrasound?
Ultrasound technology is highly valuable for regularly reviewing breast lumps that have already been identified as probably harmless. It carefully checks for any changes to the lump’s appearance.
Ultrasound is commonly used to take a closer look at lumps found during earlier imaging tests. The information gathered from an ultrasound helps to determine if the lump needs to be reevaluated as potentially harmful.
During a full ultrasound exam, a comprehensive report is generated. This includes why the patient is having the test, the findings, and potential explanations for the findings. This could potentially highlight any abnormalities.
Each lump discovered in the tests is measured in different orientations (sideways and up-down). Its location, size, and whether it reflects sound waves well (echogenicity) which could be either low (hypoechoic), high (hyperechoic), or uneven (heterogeneous) are all carefully documented.
Breast ultrasound tests use a uniform system to describe lumps, and this includes six main descriptions for their shapes.
Usually, lumps identified as harmless on an ultrasound show similarities, such as:
- Smooth and clearly defined edges
- Echogenicity that is high, same as, or slightly less than the surrounding tissue
- Slim and clear boundaries
- Oval shape, appearing wider than tall
- Having large lobes; fewer than 3 lobulated edges
- Increased echo behind the lump
Lumps that are more likely to be harmful often have a different appearance:
- Less reflection of sound waves, occasionally, high in appearance
- Serrated edges
- Rough borders, disrupted architecture of surrounding soft tissue
- Decreased echo behind the lump
- Appearing taller than wide
- Microcalcifications – tiny calcium deposits occur within the breast tissue
In men, significant fibroglandular tissue (breast tissue in men) can often be felt as an abnormal “flame-shaped” area behind the nipple. Certain medications and illegal drugs can stimulate the development of this otherwise underdeveloped tissue in men.
When a breast ultrasound report is made, it should include the following:
- Reason for the test
- Comparison to past studies if relevant
- The technique used for the exam, including what tissue was tested and how the patient was positioned, whether Doppler imaging was used, and if 3D imaging was used
- A brief outline of the composition of the breast
- Suitable description of a finding to include sonographic features, size, and location
- BI-RADS assessment, a scale from 0 to 6 used to specify how likely it is that the lump is cancer
- Suggestions for follow-up, biopsy, or any other course of action