Advances in Breast Imaging: Evolution & History of Mammography

When most people think of breast imaging, they immediately think of mammography. Mammography remains the mainstay of breast imaging, though this subspecialty area of radiology has evolved rapidly and substantially during the last several decades to include several other advances technologies that aid in the detection and diagnoses of breast diseases. I recently discussed the advances in mammography and breast imaging as a whole in San Francisco Medicine.

With this evolving technology, comes the evolving role of the breast imaging radiologist. In the past, breast imaging radiologists merely interpreted imaging and provided reports to referring physicians. Today, breast imaging radiologists play an integral part of a multidisciplinary team caring for patients with breast cancer and other breast health issues.

The Advent of Mammography Screening

In the 1960s, radiologists performed mammography exams using general purpose X-ray tubes and no compression. They captured the imaging onto direct-exposure films, similar to chest X-rays. These images were low in contrast and the area of tissue close to the chest wall appeared “white” due to underexposure.

In the next decade, mammography advanced significantly with the introduction of screen-film mammography, which made imaging faster, required lower radiation dose, and provided greatest contract, making it easier to “see through” breast tissues. Improvements in screen-film technology and the establishment of dedicated mammography units during the 1980s and 1990s made mammography images increasingly better.

As the technology improved, mammography screening for breast cancer also became more common due to two primary factors. First, the results of multiple randomized and controlled trials demonstrated the effectiveness of mammography screening to reduce breast cancer mortality. Second, the development of effective pre-operative image-guided wire localization techniques made it easier to obtain a tissue diagnosis for suspicious lesions detected at mammography.

Regulating Mammography

With more mammography in the ‘90s, came more regulation. As the imaging exam became more widely uses and breast cancer became categorized as a public health threat, concerns about variations in mammography quality grew. After numerous quality issues were uncovered, a series of Congressional hearings were dedicated to mammography, resulting in the Mammography Quality Standards Act of 1992, imposing uniform standards nationwide. These regulations affect both the quality of breast imaging and standards radiologists must follow. In addition to providing high-quality images and interpretations, breast imaging radiologists must communicate their findings and recommendations clearly to referring providers to ensure comprehensive patient care. To help radiologists convey their findings, the American College of Radiology created and maintains the Breast Imaging Reporting and Data System, or BI-RADS, a structured reporting language for breast cancer.

A New Age of Mammography

At the turn of the century, breast imaging experienced another significant advancement with the introduction of digital mammography. While digital mammography is performed the same way as analog from the patient perspective, the machine uses signals to produce images that can be read on computers rather than X-ray film.

Today, most radiology practices in the U.S. now use digital mammography because, compared to analog film, it provides better quality images with improved tissue contrast. Studies have shown that digital mammography is particularly better than film mammography for dense breasts, as well as for younger patients, who tend to have denser breast than older patients. Digital mammography also has the added benefit of lower radiation dose compared to traditional analog mammography.

Looking forward, digital breast tomosynthesis (DBT) is a promising new technology that acquires multiple low-dose mammographic projections through the breast. DBT has been shown to reduce false-positive findings and improve the detection rate of invasive cancers. Hence, DBT has been called “a better mammogram” and just may become the standard for mammographic screening once more vendors obtain the propped approvals to offer the technology.

A Critical Practice

Mammography has come a long way from the days of direct-exposure films and rampant quality concerns. Breast imaging radiologists now have more tools at their disposal and are more integrated into patient care than ever before. As additional technological innovations are achieved and breast imaging radiologists continue to advance in their expertise, mammography is expected to remain central to early detection efforts.

Early detection remains a key to reducing mortality. Mammography remains the most effective and affordable tool for detecting breast cancer and we continue to advocate for annual mammography screening starting at age 40.

Read my full article in San Francisco Medicine.

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