As more and more evidence about the long-term benefits of mammography screening in terms of mortality reduction is becoming publicly available, the role of mammography in the overall schema of screening for the early detection of breast cancer becomes less controversial . Mammography, in general, and full-field digital mammography (FFDM), in particular (or some modification thereof), is likely to remain a primary screening tool for the foreseeable future despite the less than optimal sensitivity and specificity associated with this approach to imaging of the breast for this purpose . To date, it appears that most recommendations for improving screening programs with additional imaging expect the “new” modalities to supplement, rather than replace, mammography . Women with heterogeneously dense or very dense breast tissue (typically rated density BIRADS 3 or 4) are particularly difficult to diagnose correctly with mammography, because overlapping tissue structures may mask the abnormality in question . It seems that all new imaging modalities designed to improve early detection and diagnoses of breast cancer in recent years focused primarily on this group of women, and, in many ways, compete with each other as to the role these modalities may play in screening this group. To date, these adjunct technologies to two-dimensional FFDM imaging include structural imaging based modalities, such as ultrasound (with or without tissue elastography) , dynamic imaging–based modalities, such as contrast-enhanced magnetic resonance imaging , and tissue-related functional imaging (molecular imaging) such as positron emission mammography and other molecular imaging based approaches . Each approach has both diagnostic and workflow advantages and limitations. Over the years, we have learned that under a screening paradigm, operational efficiency in terms of workflow, professional resource utilization as well as participant management issues, such as the need for repeated injections, frequently constitute important factors in our willingness and/or ability to successfully implement a very large volume of additional procedures into screening practices for the early detection of breast cancer.
Digital breast tomosynthesis addresses some of the tissue overlapping issues in breast imaging, and it has evolved in the last decade from being strictly an investigational tool to a US Food and Drug Administration (FDA)–approved imaging approach for the screening and diagnosis of breast cancer . Because of its relatively simple operational adaptation into clinical practice, the use of digital breast tomosynthesis is likely to increase substantially in the near future.
The excellent review article by Baker et al, in this issue of Academic Radiology , describes how tomosynthesis evolved into its current state and how it could address the fundamental tissue overlapping problem associated with FFDM by taking advantage of imaging technology that is already used in digital imaging in general and in breast imaging in particular. It is not very often that a new x-ray–based imaging technology generates such a “wow” factor, and is expected to potentially make a big difference in our clinical practice. Clearly, advances in large-area digital detectors in general and FFDM technology in particular in the last two decades enabled the development and adaptation of tomosynthesis to breast imaging, and possibly to imaging of other organs as well . The review article by Baker et al describes the advances in the field that led to the recent, somewhat historical, approval of tomosynthesis by the FDA for use in screening and diagnosis of breast cancer . Undoubtedly, the current state of tomosynthesis represents just the beginning of the road for this technology. Tomosynthesis will eventually find its appropriate role only when it is implemented in the routine clinical practice in the hands of many clinicians who are frequent users. As discussed in the review article, the limited number of observer studies performed to date suggests that there is potential for improving performance substantially when using tomosynthesis as an adjunct to mammography, and potentially it could eventually be used alone (without FFDM) as well. As discussed in the article, tomosynthesis has significant operational and workflow advantages over many other imaging technologies, because operationally, the performance of the procedure constitutes virtually a minor modification of conventional mammography. These advantages include, but definitely are not limited to, full registration between the two- and three-dimensional images and the possibility of using tomosynthesis with somewhat lower physical breast compression. However, to date, as approved by the FDA, tomosynthesis has some distinct limitations as well, including, but not limited to, that it requires additional radiation exposure to the breast being imaged . However, this issue is under investigation and it is quite possible that in the near future tomosynthesis studies will be performed at a comparable dose to conventional mammography. Other issues that will need to be addressed are related to the need for training , the possible increase in interpretation time , and the development of computer-assisted diagnosis tools .
It is a difficult task to review state-of-the-art technology in an environment where advancements in the technology of interest remain frequent and significant. Yet, the authors provide a comprehensive review with an excellent perspective on the evolution, the present day status and application, and the future possibilities, in terms of science, possible new applications, and optimal utilization of this new and exciting technology.
It is only through extensive prospective clinical use in different screening and diagnostic environments that we will be able to better understand and advance this breast imaging approach to its optimal role in clinical practice. Eventually, tomosynthesis may play an important role in optimized, personalized screening . As correctly noted by the authors, the work in this regard has just begun.
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