Did you know?
- 70% of diagnostic errors result from radiologists not seeing abnormalities within images.
- Breast cancer is the most commonly missed diagnosis for radiologists.
Mammograms can be challenging to read because evidence of breast cancers—subtle masses and calcifications, and slight changes in tissue density—can often blend into surrounding healthy tissue. As radiologists can attest, dense breast tissue appears white on a mammogram—but, unfortunately, so do cancers. The denser the patient’s breast tissue naturally is, the greater the challenge in identifying these indicators. Abnormalities need to be clearly visible to achieve earlier diagnoses and better patient outcomes.
As with all imaging modalities, the effectiveness of mammograms comes down to image quality and what radiologists are able to see.
The Importance of Screen Resolution
Alongside display brightness, screen resolution is the most important factor influencing the quality of breast images, the ability for radiologists to detect subtle abnormalities earlier in the development of medical conditions, and the accuracy of diagnostic interpretation. Screen resolution impacts the sharpness and clarity of the image and, therefore, how many minute details can be seen.
What is resolution, exactly?
Resolution is defined in megapixels. A single megapixel represents one million pixels. To break it down, a pixel is simply the smallest part of an image—one dot. When combined, all the millions of individual pixels in an image form a complete picture. You can calculate total megapixels by multiplying the number of individual vertical pixels by the number of individual horizontal pixels, and then dividing that figure by one million.
Remember: The higher the resolution, the more elements are contained within an image and the more details are visible on the screen.
Why 5MP (or higher)
The American College of Radiology (ACR) and other industry organizations around the world recommend that the resolution of mammography displays should closely—if not precisely—match the resolution of the imaging system that captured the image under analysis. Because the resolution of breast imaging is so high, radiologists need at least 5MP—five million pixels—to reproduce them accurately on a screen and be able to view them 1:1, or at 100%, in full resolution.
If the mammography display lacks sufficient resolution, which means that there are more elements in the breast image than available pixels on the screen, radiologists have to manipulate the image to view it at full-size resolution. This could involve panning, zooming, scaling, or windowing to achieve the best view of an image for analysis. This takes up a lot of time for radiologists. And, in the process, critical details within the image could be lost, which would have a negative impact on radiologists’ decisions and, ultimately, patient care.
But with a mammography display that’s 5MP per screen or higher, radiologists can fit more of the mammogram within the display and see more detail with little to no image manipulation necessary. For radiologists who study about 40 images per day on average, this saves time and increases productivity.
Mammography displays that meet these requirements also provide ergonomic benefits that enhance radiologists’ comfort and ability to read images for longer periods.
Legal Requirements Under the Mammography Quality Standards Act (MQSA)
Clearly, higher-resolution mammography displays lead to more accurate diagnoses at earlier stages of disease progression, improve patient care and health outcomes, and enable a more comfortable, productive reading experience for radiologists. For these reasons, industry groups such as the ACR have set guidelines recommending displays of 5MP or higher.
But radiologists are also required by law to read cases on equipment that meets certain minimum standards. Alongside other region-specific laws passed by governments around the world, one of the most prominent and stringent pieces of legislation is the MQSA.
Passed by Congress in 1992 and overseen and enforced by the U.S. Food and Drug Administration (FDA), the MQSA establishes standards for image presentation on monitor screens. Part of this law mandates that each monitor in the typical dual-head display set-up have a screen size of 21 inches and a resolution of 5MP. (If you opt for a single fusion display, these monitors go up to 12MP and have screen sizes between 30 to 33 inches.)
Additionally, the MQSA requires mammography display monitors to undergo strict quality-assurance (QA) tests by qualified medical physicists as part of regular FDA inspections of mammography facilities. These QA tests focus on screen resolution, brightness, and contrast, and require that minimum standards for each be present in mammography display monitors. Facilities must preserve the test results.